- PERIOD
- Last 30 days
- per year
- whole period
Recent advances on the transition-metal-catalyzed synthesis of imidazopyridines: an updated coverage
- Gagandeep Kour Reen,
- Ashok Kumar and
- Pratibha Sharma
Beilstein J. Org. Chem. 2019, 15, 1612–1704, doi:10.3762/bjoc.15.165
Graphical Abstract
Figure 1: Various drugs having IP nucleus.
Figure 2: Participation percentage of various TMs for the syntheses of IPs.
Scheme 1: CuI–NaHSO4·SiO2-catalyzed synthesis of imidazo[1,2-a]pyridines.
Scheme 2: Experimental examination of reaction conditions.
Scheme 3: One-pot tandem reaction for the synthesis of 2-haloimidazopyridines.
Scheme 4: Mechanistic scheme for the synthesis of 2-haloimidazopyridine.
Scheme 5: Copper-MOF-catalyzed three-component reaction (3-CR) for imidazo[1,2-a]pyridines.
Scheme 6: Mechanism for copper-MOF-driven synthesis.
Scheme 7: Heterogeneous synthesis via titania-supported CuCl2.
Scheme 8: Mechanism involving oxidative C–H functionalization.
Scheme 9: Heterogeneous synthesis of IPs.
Scheme 10: One-pot regiospecific synthesis of imidazo[1,2-a]pyridines.
Scheme 11: Vinyl azide as an unprecedented substrate for imidazo[1,2-a]pyridines.
Scheme 12: Radical pathway.
Scheme 13: Cu(I)-catalyzed transannulation approach for imidazo[1,5-a]pyridines.
Scheme 14: Plausible radical pathway for the synthesis of imidazo[1,5-a]pyridines.
Scheme 15: A solvent-free domino reaction for imidazo[1,2-a]pyridines.
Scheme 16: Cu-NPs-mediated synthesis of imidazo[1,2-a]pyridines.
Scheme 17: CuI-catalyzed synthesis of isoxazolylimidazo[1,2-a]pyridines.
Scheme 18: Functionalization of 4-bromo derivative via Sonogashira coupling reaction.
Scheme 19: A plausible reaction pathway.
Scheme 20: Cu(I)-catalyzed intramolecular oxidative C–H amidation reaction.
Scheme 21: One-pot synthetic reaction for imidazo[1,2-a]pyridine.
Scheme 22: Plausible reaction mechanism.
Scheme 23: Cu(OAc)2-promoted synthesis of imidazo[1,2-a]pyridines.
Scheme 24: Mechanism for aminomethylation/cycloisomerization of propiolates with imines.
Scheme 25: Three-component synthesis of imidazo[1,2-a]pyridines.
Figure 3: Scope of pyridin-2(1H)-ones and acetophenones.
Scheme 26: CuO NPS-promoted A3 coupling reaction.
Scheme 27: Cu(II)-catalyzed C–N bond formation reaction.
Scheme 28: Mechanism involving Chan–Lam/Ullmann coupling.
Scheme 29: Synthesis of formyl-substituted imidazo[1,2-a]pyridines.
Scheme 30: A tandem sp3 C–H amination reaction.
Scheme 31: Probable mechanistic approach.
Scheme 32: Dual catalytic system for imidazo[1,2-a]pyridines.
Scheme 33: Tentative mechanism.
Scheme 34: CuO/CuAl2O4/ᴅ-glucose-promoted 3-CCR.
Scheme 35: A tandem CuOx/OMS-2-based synthetic strategy.
Figure 4: Biomimetic catalytic oxidation in the presence of electron-transfer mediators (ETMs).
Scheme 36: Control experiment.
Scheme 37: Copper-catalyzed C(sp3)–H aminatin reaction.
Scheme 38: Reaction of secondary amines.
Scheme 39: Probable mechanistic pathway.
Scheme 40: Coupling reaction of α-azidoketones.
Scheme 41: Probable pathway.
Scheme 42: Probable mechanism with free energy calculations.
Scheme 43: MCR for cyanated IP synthesis.
Scheme 44: Substrate scope for the reaction.
Scheme 45: Reaction mechanism.
Scheme 46: Probable mechanistic pathway for Cu/ZnAl2O4-catalyzed reaction.
Scheme 47: Copper-catalyzed double oxidative C–H amination reaction.
Scheme 48: Application towards different coupling reactions.
Scheme 49: Reaction mechanism.
Scheme 50: Condensation–cyclization approach for the synthesis of 1,3-diarylated imidazo[1,5-a]pyridines.
Scheme 51: Optimized reaction conditions.
Scheme 52: One-pot 2-CR.
Scheme 53: One-pot 3-CR without the isolation of chalcone.
Scheme 54: Copper–Pybox-catalyzed cyclization reaction.
Scheme 55: Mechanistic pathway catalyzed by Cu–Pybox complex.
Scheme 56: Cu(II)-promoted C(sp3)-H amination reaction.
Scheme 57: Wider substrate applicability for the reaction.
Scheme 58: Plausible reaction mechanism.
Scheme 59: CuI assisted C–N cross-coupling reaction.
Scheme 60: Probable reaction mechanism involving sp3 C–H amination.
Scheme 61: One-pot MCR-catalyzed by CoFe2O4/CNT-Cu.
Scheme 62: Mechanistic pathway.
Scheme 63: Synthetic scheme for 3-nitroimidazo[1,2-a]pyridines.
Scheme 64: Plausible mechanism for CuBr-catalyzed reaction.
Scheme 65: Regioselective synthesis of halo-substituted imidazo[1,2-a]pyridines.
Scheme 66: Synthesis of 2-phenylimidazo[1,2-a]pyridines.
Scheme 67: Synthesis of diarylated compounds.
Scheme 68: CuBr2-mediated one-pot two-component oxidative coupling reaction.
Scheme 69: Decarboxylative cyclization route to synthesize 1,3-diarylimidazo[1,5-a]pyridines.
Scheme 70: Mechanistic pathway.
Scheme 71: C–H functionalization reaction of enamines to produce diversified heterocycles.
Scheme 72: A plausible mechanism.
Scheme 73: CuI-promoted aerobic oxidative cyclization reaction of ketoxime acetates and pyridines.
Scheme 74: CuI-catalyzed pathway for the formation of imidazo[1,2-a]pyridine.
Scheme 75: Mechanistic pathway.
Scheme 76: Mechanistic rationale for the synthesis of products.
Scheme 77: Copper-catalyzed synthesis of vinyloxy-IP.
Scheme 78: Regioselective product formation with propiolates.
Scheme 79: Proposed mechanism for vinyloxy-IP formation.
Scheme 80: Regioselective synthesis of 3-hetero-substituted imidazo[1,2-a]pyridines with different reaction su...
Scheme 81: Mechanistic pathway.
Scheme 82: CuI-mediated synthesis of 3-formylimidazo[1,2-a]pyridines.
Scheme 83: Radical pathway for 3-formylated IP synthesis.
Scheme 84: Pd-catalyzed urea-cyclization reaction for IPs.
Scheme 85: Pd-catalyzed one-pot-tandem amination and intramolecular amidation reaction.
Figure 5: Scope of aniline nucleophiles.
Scheme 86: Pd–Cu-catalyzed Sonogashira coupling reaction.
Scheme 87: One-pot amide coupling reaction for the synthesis of imidazo[4,5-b]pyridines.
Scheme 88: Urea cyclization reaction for the synthesis of two series of pyridines.
Scheme 89: Amidation reaction for the synthesis of imidazo[4,5-b]pyridines.
Figure 6: Amide scope.
Scheme 90: Pd NPs-catalyzed 3-component reaction for the synthesis of 2,3-diarylated IPs.
Scheme 91: Plausible mechanistic pathway for Pd NPs-catalyzed MCR.
Scheme 92: Synthesis of chromenoannulated imidazo[1,2-a]pyridines.
Scheme 93: Mechanism for the synthesis of chromeno-annulated IPs.
Scheme 94: Zinc oxide NRs-catalyzed synthesis of imidazo[1,2-a]azines/diazines.
Scheme 95: Zinc oxide-catalyzed isocyanide based GBB reaction.
Scheme 96: Reaction pathway for ZnO-catalyzed GBB reaction.
Scheme 97: Mechanistic pathway.
Scheme 98: ZnO NRs-catalyzed MCR for the synthesis of imidazo[1,2-a]azines.
Scheme 99: Ugi type GBB three-component reaction.
Scheme 100: Magnetic NPs-catalyzed synthesis of imidazo[1,2-a]pyridines.
Scheme 101: Regioselective synthesis of 2-alkoxyimidazo[1,2-a]pyridines catalyzed by Fe-SBA-15.
Scheme 102: Plausible mechanistic pathway for the synthesis of 2-alkoxyimidazopyridine.
Scheme 103: Iron-catalyzed synthetic approach.
Scheme 104: Iron-catalyzed aminooxygenation reaction.
Scheme 105: Mechanistic pathway.
Scheme 106: Rh(III)-catalyzed double C–H activation of 2-substituted imidazoles and alkynes.
Scheme 107: Plausible reaction mechanism.
Scheme 108: Rh(III)-catalyzed non-aromatic C(sp2)–H bond activation–functionalization for the synthesis of imid...
Scheme 109: Reactivity and selectivity of different substrates.
Scheme 110: Rh-catalyzed direct C–H alkynylation by Li et al.
Scheme 111: Suggested radical mechanism.
Scheme 112: Scandium(III)triflate-catalyzed one-pot reaction and its mechanism for the synthesis of benzimidazo...
Scheme 113: RuCl3-assisted Ugi-type Groebke–Blackburn condensation reaction.
Scheme 114: C-3 aroylation via Ru-catalyzed two-component reaction.
Scheme 115: Regioselective synthetic mechanism.
Scheme 116: La(III)-catalyzed one-pot GBB reaction.
Scheme 117: Mechanistic approach for the synthesis of imidazo[1,2-a]pyridines.
Scheme 118: Synthesis of imidazo[1,2-a]pyridine using LaMnO3 NPs under neat conditions.
Scheme 119: Mechanistic approach.
Scheme 120: One-pot 3-CR for regioselective synthesis of 2-alkoxy-3-arylimidazo[1,2-a]pyridines.
Scheme 121: Formation of two possible products under optimization of the catalysts.
Scheme 122: Mechanistic strategy for NiFe2O4-catalyzed reaction.
Scheme 123: Two-component reaction for synthesizing imidazodipyridiniums.
Scheme 124: Mechanistic scheme for the synthesis of imidazodipyridiniums.
Scheme 125: CuI-catalyzed arylation of imidazo[1,2-a]pyridines.
Scheme 126: Mechanism for arylation reaction.
Scheme 127: Cupric acetate-catalyzed double carbonylation approach.
Scheme 128: Radical mechanism for double carbonylation of IP.
Scheme 129: C–S bond formation reaction catalyzed by cupric acetate.
Scheme 130: Cupric acetate-catalyzed C-3 formylation approach.
Scheme 131: Control experiments for signifying the role of DMSO and oxygen.
Scheme 132: Mechanism pathway.
Scheme 133: Copper bromide-catalyzed CDC reaction.
Scheme 134: Extension of the substrate scope.
Scheme 135: Plausible radical pathway.
Scheme 136: Transannulation reaction for the synthesis of imidazo[1,5-a]pyridines.
Scheme 137: Plausible reaction pathway for denitrogenative transannulation.
Scheme 138: Cupric acetate-catalyzed C-3 carbonylation reaction.
Scheme 139: Plausible mechanism for regioselective C-3 carbonylation.
Scheme 140: Alkynylation reaction at C-2 of 3H-imidazo[4,5-b]pyridines.
Scheme 141: Two-way mechanism for C-2 alkynylation of 3H-imidazo[4,5-b]pyridines.
Scheme 142: Palladium-catalyzed SCCR approach.
Scheme 143: Palladium-catalyzed Suzuki coupling reaction.
Scheme 144: Reaction mechanism.
Scheme 145: A phosphine free palladium-catalyzed synthesis of C-3 arylated imidazopyridines.
Scheme 146: Palladium-mediated Buchwald–Hartwig cross-coupling reaction.
Figure 7: Structure of the ligands optimized.
Scheme 147: Palladium acetate-catalyzed direct arylation of imidazo[1,2-a]pyridines.
Scheme 148: Palladium acetate-catalyzed mechanistic pathway.
Scheme 149: Palladium acetate-catalyzed regioselective arylation reported by Liu and Zhan.
Scheme 150: Mechanism for selective C-3 arylation of IP.
Scheme 151: Pd(II)-catalyzed alkenylation reaction with styrenes.
Scheme 152: Pd(II)-catalyzed alkenylation reaction with acrylates.
Scheme 153: A two way mechanism.
Scheme 154: Double C–H activation reaction catalyzed by Pd(OAc)2.
Scheme 155: Probable mechanism.
Scheme 156: Palladium-catalyzed decarboxylative coupling.
Scheme 157: Mechanistic cycle for decarboxylative arylation reaction.
Scheme 158: Ligand-free approach for arylation of imidazo[1,2-a]pyridine-3-carboxylic acids.
Scheme 159: Mechanism for ligandless arylation reaction.
Scheme 160: NHC-Pd(II) complex assisted arylation reaction.
Scheme 161: C-3 arylation of imidazo[1,2-a]pyridines with aryl bromides catalyzed by Pd(OAc)2.
Scheme 162: Pd(II)-catalyzed C-3 arylations with aryl tosylates and mesylates.
Scheme 163: CDC reaction for the synthesis of imidazo[1,2-a]pyridines.
Scheme 164: Plausible reaction mechanism for Pd(OAc)2-catalyzed synthesis of imidazo[1,2-a]pyridines.
Scheme 165: Pd-catalyzed C–H amination reaction.
Scheme 166: Mechanism for C–H amination reaction.
Scheme 167: One-pot synthesis for 3,6-di- or 2,3,6-tri(hetero)arylimidazo[1,2-a]pyridines.
Scheme 168: C–H/C–H cross-coupling reaction of IPs and azoles catalyzed by Pd(II).
Scheme 169: Mechanistic cycle.
Scheme 170: Rh-catalyzed C–H arylation reaction.
Scheme 171: Mechanistic pathway for C–H arylation of imidazo[1,2-a]pyridine.
Scheme 172: Rh(III)-catalyzed double C–H activation of 2-phenylimidazo[1,2-a]pyridines and alkynes.
Scheme 173: Rh(III)-catalyzed mechanistic pathway.
Scheme 174: Rh(III)-mediated oxidative coupling reaction.
Scheme 175: Reactions showing functionalization of the product obtained by the group of Kotla.
Scheme 176: Mechanism for Rh(III)-catalyzed oxidative coupling reaction.
Scheme 177: Rh(III)-catalyzed C–H activation reaction.
Scheme 178: Mechanistic cycle.
Scheme 179: Annulation reactions of 2-arylimidazo[1,2-a]pyridines and alkynes.
Scheme 180: Two-way reaction mechanism for annulations reaction.
Scheme 181: [RuCl2(p-cymene)]2-catalyzed C–C bond formation reaction.
Scheme 182: Reported reaction mechanism.
Scheme 183: Fe(III) catalyzed C-3 formylation approach.
Scheme 184: SET mechanism-catalyzed by Fe(III).
Scheme 185: Ni(dpp)Cl2-catalyzed KTC coupling.
Scheme 186: Pd-catalyzed SM coupling.
Scheme 187: Vanadium-catalyzed coupling of IP and NMO.
Scheme 188: Mechanistic cycle.
Scheme 189: Selective C3/C5–H bond functionalizations by mono and bimetallic systems.
Scheme 190: rGO-Ni@Pd-catalyzed C–H bond arylation of imidazo[1,2-a]pyridine.
Scheme 191: Mechanistic pathway for heterogeneously catalyzed arylation reaction.
Scheme 192: Zinc triflate-catalyzed coupling reaction of substituted propargyl alcohols.
Recent advancements in the synthesis of Veratrum alkaloids
- Morwenna Mögel,
- David Berger and
- Philipp Heretsch
Beilstein J. Org. Chem. 2025, 21, 2657–2693, doi:10.3762/bjoc.21.206
Graphical Abstract
Scheme 1: Representatives of steroid alkaloid classes. Marked in blue is the steroidal cholestane framework, ...
Scheme 2: Subclasses of Veratrum alkaloids: jervanine, veratramine and cevanine-type [8].
Scheme 3: Flow chart presentation of the synthesis of (−)-englerin A developed by the Christmann group [10].
Scheme 4: Structures and year of synthesis of the three types of Veratrum alkaloids reported in the literatur...
Scheme 5: Key step in the synthesis of cyclopamine (6) by the Giannis group [21].
Scheme 6: Overview of the semisynthesis of cyclopamine (6) reported by the Giannis group in 2009 [21].
Scheme 7: Key steps in the synthesis of cyclopamine (6) by the Baran group [23].
Scheme 8: Overview of the total synthesis of cyclopamine (6) by the Baran group in 2023 [23].
Scheme 9: Key steps in the synthesis of cyclopamine (6) by the Zhu/Gao group [25].
Scheme 10: Overview of the total synthesis of cyclopamine (6) by the group of Zhao/Gao in 2023 [25].
Scheme 11: Key steps in the synthesis of cyclopamine (6) by the Liu/Qin group [26].
Scheme 12: Overview of the semisynthesis of cyclopamine (6) by the Liu/Qin group in 2024 [26].
Scheme 13: Key steps in the synthesis of jervine (12) by the Masamune group [14].
Scheme 14: Overview of the total synthesis of jervine (12) by the Masamune group in 1968 [14].
Scheme 15: Color-coded schemes of the presented cyclopamine (6) syntheses by Giannis, Baran, Zhu/Gao, and Liu/...
Scheme 16: Key steps in the total synthesis of veratramine (13) by the Johnson group [15].
Scheme 17: Overview of the total synthesis of veratramine (13) by the Johnson group in 1967 [15].
Scheme 18: Key steps in the synthesis of veratramine (13) by the Zhu/Gao group [25].
Scheme 19: Shortened overview of the total synthesis of veratramine (13) by the Zhu/Gao group in 2023 [25].
Scheme 20: Key steps in the synthesis of veratramine by the Liu/Qin group [26].
Scheme 21: Overview of the semisynthesis of veratramine (13) by the Liu/Qin group in 2024 [26].
Scheme 22: Key steps in the synthesis of veratramine (13) by the Trauner group [27].
Scheme 23: Overview of the total synthesis of veratramine (13) by the Trauner group in 2025 [27].
Scheme 24: Key steps in the synthesis of verarine (14) by the Kutney group [16-19].
Scheme 25: Overview of the total synthesis of verarine (14) by the Kutney group reported 1962–1968 [16-19].
Scheme 26: Color-coded schemes of the presented veratramine-type alkaloid synthesis of Zhu/Gao, Liu/Qin and Tr...
Scheme 27: Structures of veracevine (86), veratridine (87), and cevadine (88).
Scheme 28: Key step in the semisynthesis of verticine (15) by the Kutney group (1977) [20,46].
Scheme 29: Overview of the semisynthesis of verticine (15) by the Kutney group (1977) [20,46].
Scheme 30: Key step of the total synthesis of (±)-4-methylenegermine (17) by the Stork group (2017) [22].
Scheme 31: Overview of the total synthesis of (±)-4-methylenegermine (17) by the Stork group (2017) [22].
Scheme 32: Key step of the total synthesis of heilonine (16) by Cassaidy and Rawal (2021) [24].
Scheme 33: Overview of the total synthesis of heilonine (16) by Cassaidy and Rawal (2021) [24]. FGI: functional gr...
Scheme 34: Key steps of the synthesis of heilonine (16) by Dai and co-workers (2024) [28].
Scheme 35: Overview of the total synthesis of heilonine (16) by Dai and co-workers (2024) [28].
Scheme 36: Key steps of the total synthesis of zygadenine (18) reported by Luo and co-workers [29].
Scheme 37: Overview of the total synthesis of zygadenine (18) by Luo and co-workers (2023) [29].
Scheme 38: Key step of the divergent total syntheses of highly oxidized cevanine-type alkaloids by Luo and co-...
Scheme 39: Divergent syntheses of highly oxidized cevanine-type alkaloids by Luo and co-workers (2024) [30].
Scheme 40: Color-coded overview of the presented cevanine-type alkaloid syntheses [10,20,22,24,28-30,46]. LLS: longest linear sequen...
Synthetic approaches to bowl-shaped π-conjugated sumanene and its congeners
- Shakeel Alvi and
- Rashid Ali
Beilstein J. Org. Chem. 2020, 16, 2212–2259, doi:10.3762/bjoc.16.186
Graphical Abstract
Figure 1: Representation of corannulene (1) and sumanene (2), the subunits of fullerene (C60).
Scheme 1: Mehta’s unsuccessful effort for the synthesis of sumanene scaffold 2.
Scheme 2: First synthesis of sumanene 2 by Sakurai et al. from norbornadiene 10.
Scheme 3: Synthesis of trimethylsumanene 28 from easily accessible norbornadiene (10).
Scheme 4: Generation of anions 29–31 and the preparation of tris(trimethylsilyl)sumanene 32.
Scheme 5: Synthesis of tri- and hexa-substituted sumanene derivatives.
Scheme 6: Synthesis of bowl-shaped π-extended sumanene derivatives 37a–f.
Scheme 7: Synthesis of monooxasumanene 38, trioxosumanene 40 along with imination of them.
Scheme 8: Synthesis of trimethylsumanenetrione 46 and exo-functionalized products 45a,b.
Scheme 9: Synthesis of bisumanenylidene 47 and sumanene dimer 48 from 2.
Scheme 10: The mono-substitution of 2 to generate diverse mono-sumanene derivatives 49a–d.
Scheme 11: Synthesis of sumanene building block 53 useful for further extension.
Scheme 12: Synthesis of hexafluorosumanene derivative 55 by Sakurai and co-workers.
Scheme 13: Preparation of sumanene-based carbene 60 and its reaction with cyclohexane.
Scheme 14: Barton–Kellogg reaction for the synthesis of sterically hindered alkenes.
Scheme 15: Synthesis of hydroxysumanene 68 by employing Baeyer–Villiger oxidation.
Scheme 16: Synthesis of sumanene derivatives having functionality at an internal carbon.
Scheme 17: Mechanism for nucleophilic substitution reaction at the internal carbon.
Scheme 18: Synthesis of diverse monosubstituted sumanene derivatives.
Scheme 19: Synthesis of di- and trisubstituted sumanene derivatives from sumanene (2).
Scheme 20: Preparation of monochlorosumanene 88 and hydrogenation of sumanene (2).
Scheme 21: The dimer 90 and bissumanenyl 92 achieved from halosumannes.
Scheme 22: Pyrenylsumanene 93 involving the Suzuki-coupling as a key transformation.
Scheme 23: Synthesis of various hexaarylsumanene derivatives using the Suzuki-coupling reaction.
Scheme 24: Synthesis of hexasubstituted sumanene derivatives 96 and 97.
Scheme 25: Synthesis of thioalkylsumanenes via an aromatic nucleophilic substitution reaction.
Scheme 26: Synthesis of tris(ethoxycarbonylethenyl)sumanene derivative 108.
Scheme 27: Synthesis of ferrocenyl-based sumanene derivatives.
Scheme 28: Synthesis of sumanenylferrocene architectures 118 and 119 via Negishi coupling.
Scheme 29: Diosmylation and the synthesis of phenylboronate ester 121 of sumanene.
Scheme 30: Synthesis of the iron-complex of sumanene.
Scheme 31: Synthesis of tri- and mononuclear sumanenyl zirconocene complexes.
Scheme 32: Synthesis of [CpRu(η6-sumanene)]PF6.
Scheme 33: Preparation of sumanene-based porous coordination networks 127 (spherical tetramer units) and 128 (...
Scheme 34: Synthesis of sumanenylhafnocene complexes 129 and 130.
Scheme 35: Synthesis of 134 and 135 along with PdII coordination complex 136.
Scheme 36: Synthesis of alkali metals sumanene complex K7(C21H102−)2(C21H93−)·8THF (137) containing di- and tr...
Scheme 37: The encapsulation of a Cs+ ion between two sumanenyl anions.
Scheme 38: Synthesis of monothiasumanene 140 and dithiasumanene 141 from 139.
Scheme 39: Synthesis of trithiasumanene 151 by Otsubo and his co-workers.
Scheme 40: Synthesis of trithiasumanene derivatives 155 and 156.
Scheme 41: Synthetic route towards hexathiolated trithiasumanenes 158.
Scheme 42: Synthesis of triselenasumanene 160 by Shao and teammates.
Scheme 43: Synthesis of tritellurasumanene derivatives from triphenylene skeletons.
Scheme 44: Synthesis of pyrazine-fused sumanene architectures through condensation reaction.
Scheme 45: Treatment of the trichalcogenasumanenes with diverse oxidative reagents.
Scheme 46: Ring-opening reaction with H2O2 and oxone of heterasumanenes 178 and 179.
Scheme 47: Synthesis of polycyclic compounds from sumanene derivatives.
Scheme 48: Synthesis of diimide-based heterocycles reported by Shao’s and co-workers.
Scheme 49: Synthesis of pristine trichalcogenasumanenes, 151, 205, and 206.
Scheme 50: Synthesis of trichalcogenasumanenes via hexaiodotriphenylene precursor 208.
Scheme 51: Synthesis of trisilasumanenes 214 and 215.
Scheme 52: Synthesis of trisilasumanene derivatives 218 and 219.
Scheme 53: Synthesis of novel trigermasumanene derivative 223.
Scheme 54: An attempt towards the synthesis of tristannasumanene derivative 228.
Scheme 55: Synthesis of triphosphasumanene trisulfide 232 from commercially available 229.
Scheme 56: The doping of sumanene derivatives with chalcogens (S, Se, Te) and phosphorus.
Scheme 57: Synthesis of heterasumanene containing three different heteroatoms.
Scheme 58: Synthesis of trichalcogenasumanene derivatives 240 and 179.
Scheme 59: Preparation of trichalcogenasumanenes 245 and 248.
Scheme 60: Design and synthesis of trichalcogenasumanene derivatives 252 and 178.
Scheme 61: Synthesis of spirosumanenes 264–269 and non-spiroheterasumanenes 258–263.
Scheme 62: Synthesis of sumanene-type hetero polycyclic compounds.
Scheme 63: Synthesis of triazasumanenes 288 and its sulfone congener 287.
Scheme 64: Synthesis of C3-symmetric chiral triaryltriazasumanenes via cross-coupling reaction.
Scheme 65: Synthesis of mononaphthosumanene 293 using Suzuki coupling as a key step.
Scheme 66: Synthesis of di- and trinaphthosumanene derivatives 302–304.
Scheme 67: Synthesis of hemifullerene skeletons by Hirao’s group.
Scheme 68: Design and construction of C70 fragment from a C60 sumanene fragment.
Amine–borane complex-initiated SF5Cl radical addition on alkenes and alkynes
- Audrey Gilbert,
- Pauline Langowski,
- Marine Delgado,
- Laurent Chabaud,
- Mathieu Pucheault and
- Jean-François Paquin
Beilstein J. Org. Chem. 2020, 16, 3069–3077, doi:10.3762/bjoc.16.256
Graphical Abstract
Scheme 1: Dolbier’s protocol for the SF5Cl radical addition on alkenes.
Scheme 2: Proposed mechanism for the amine–borane complex-initiated radical addition of SF5Cl on alkenes.
Figure 1: Structures and acronyms of the amine-borane complexes investigated.
Scheme 3: Scope of the Et3B and the DICAB-initiated SF5Cl additions on alkenes. Unless noted otherwise, isola...
Scheme 4: Scope of the Et3B and the DICAB-initiated SF5Cl additions on alkynes. Unless noted otherwise, isola...
A mild and atom-efficient four-component cascade strategy for the construction of biologically relevant 4-hydroxyquinolin-2(1H)-one derivatives
- Dmitrii A. Grishin,
- Kseniia I. Sharkovskaia,
- Ilya G. Kolmakov,
- Daria A. Ipatova,
- Rostislav A. Petrov,
- Nikolai D. Dagaev,
- Dmitry A. Skvortsov,
- Maria G. Khrenova,
- Valeriy V. Andreychev,
- Sergei A. Evteev,
- Yan A. Ivanenkov,
- Roman L. Antipin,
- Olga А. Dontsova and
- Elena K. Beloglazkina
Beilstein J. Org. Chem. 2026, 22, 244–256, doi:10.3762/bjoc.22.18
Graphical Abstract
Figure 1: Examples of biologically active quinolin-2(1H)-ones.
Figure 2: Structures obtained via rational design aimed at enhancing antibacterial activity.
Scheme 1: Previously reported and newly developed 3-(4-hydroxy-2-oxo-1,2-dihydroquinolin-3-yl)-3-arylpropanoi...
Scheme 2: Retrosynthetic analysis: two alternative approaches to target compounds.
Scheme 3: Two-stage synthesis A) and one-stage one-pot synthesis B) of 6-halogen-4-hydroxyquinoline-2(1H)-one...
Scheme 4: Previous synthetic attempts toward the target chemotype using various approaches.
Scheme 5: Four-component synthesis of 3-(6-halo-4-hydroxy-2-oxo-1,2-dihydroquinolin-3-yl)-3-(3,4-dimethoxyphe...
Scheme 6: The proposed mechanism of the four-component reaction.
Scheme 7: Synthesis of isopropyl (12a–c) and cyclohexyl (13а–с) esters of 3-(4-hydroxy-2-oxo-1,2-dihydroquino...
Figure 3: In vitro antibacterial activity studies. А) In vitro antibacterial activity using the E. coli ΔtolC...
An overview of the cycloaddition chemistry of fulvenes and emerging applications
- Ellen Swan,
- Kirsten Platts and
- Anton Blencowe
Beilstein J. Org. Chem. 2019, 15, 2113–2132, doi:10.3762/bjoc.15.209
Graphical Abstract
Figure 1: General structure of fulvenes, named according to the number of carbon atoms in their ring. Whilst ...
Figure 2: Generic structures of commonly referenced heteropentafulvenes, named according to the heteroatom su...
Scheme 1: Resonance structures of (a) pentafulvene and (b) heptafulvene showing neutral (1 and 2), dipolar (1a...
Scheme 2: Resonance structures of (a) pentafulvenes and (b) heptafulvenes showing the influence of EDG and EW...
Scheme 3: Reaction of 6,6-dimethylpentafulvene with singlet state oxygen to form an enol lactone via the mult...
Scheme 4: Photosensitized oxygenation of 8-cyanoheptafulvene with singlet state oxygen to afford 1,4-epidioxi...
Figure 3: A representation of HOMO–LUMO orbitals of pentafulvene and the influence of EWG and EDG substituent...
Scheme 5: Reactions of (a) 6,6-dimethylpentafulvene participating as 2π and 4π components in cycloadditions w...
Scheme 6: Proposed mechanism for the [6 + 4] cycloaddition of tropone with dimethylfulvene via an ambimodal [...
Scheme 7: Triafulvene dimerization through the proposed 'head-to-tail' mechanism. The dipolar transition stat...
Scheme 8: Dimerization of pentafulvenes via a Diels–Alder cycloaddition pathway whereby one fulvene acts as a...
Scheme 9: Dimerization of pentafulvenes via frustrated Lewis pair chemistry as reported by Mömming et al. [116].
Scheme 10: Simplified reaction scheme for the formation of kempane from an extended-chain pentafulvene [127].
Scheme 11: The enantioselective (>99% ee), asymmetric, catalytic, intramolecular [6 + 2] cycloaddition of fulv...
Scheme 12: Intramolecular [8 + 6] cycloaddition of the heptafulvene-pentafulvene derivative [22,27].
Scheme 13: Reaction scheme for (a) [2 + 2] cycloaddition of 1,2-diphenylmethylenecyclopropene and 1-diethylami...
Scheme 14: Diels–Alder cycloaddition of pentafulvenes derivatives participating as dienes with (i) maleimide d...
Scheme 15: Generic schemes showing pentafulvenes participating as dienophiles in Diels–Alder cycloadditions wi...
Scheme 16: Reaction of 8,8-dicyanoheptafulvene and styrene derivatives to afford [8 + 2] and [4 + 2] cycloaddu...
Scheme 17: Reaction of 6-aminofulvene and maleic anhydride, showing observed [6 + 2] cycloaddition; the [4 + 2...
Scheme 18: Schemes for Diels–Alder cycloadditions in dynamic combinatorial chemistry reported by Boul et al. R...
Scheme 19: Polymerisation and dynamer formation via Diels–Alder cycloaddition between fulvene groups in polyet...
Scheme 20: Preparation of hydrogels via Diels–Alder cycloaddition with fulvene-conjugated dextran and dichloro...
Scheme 21: Ring-opening metathesis polymerisation of norbornene derivatives derived from fulvenes and maleimid...
Synthesis of odorants in flow and their applications in perfumery
- Merlin Kleoff,
- Paul Kiler and
- Philipp Heretsch
Beilstein J. Org. Chem. 2022, 18, 754–768, doi:10.3762/bjoc.18.76
Graphical Abstract
Figure 1: The olfactory spectrum wheel ordering different types of odorants from fruity to musky.
Figure 2: Classification of odorants as “top note”, “middle note” and “base note” depending on their substant...
Scheme 1: Synthesis of raspberry ketone (5) and raspberry ketone methyl ether (6) in two steps in flow.
Scheme 2: Autoxidation of (+)-valencene (7) to (+)-nootkatone (8) under catalyst and solvent-free conditions ...
Scheme 3: Enzyme-catalyzed acetylation of isoamyl alcohol (9) in a biphasic n-heptane/water mixture utilizing...
Scheme 4: Esterification of alcohols by transesterification, catalyzed by immobilized acyltransferase in a pa...
Scheme 5: Synthesis of homologated alcohols 20 by iterative homologation of terpenyl boronate esters 17 follo...
Scheme 6: Sequential three-step synthesis of (S)-α-phellandrene (30) from (R)-carvone (25) via selective hydr...
Scheme 7: Selective hydrogenation of alkyne 31 to “leaf alcohol” 32 employing a solid-supported palladium cat...
Scheme 8: A) Synthesis of jasmonal (35) by crossed aldol condensation of benzaldehyde (33) and heptanal (34) ...
Scheme 9: Synthesis of thymol (41) from m-cresol (39) and isopropyl alcohol via Fries-type rearrangement of e...
Scheme 10: Preparation of coumarin (46) by reaction of salicylaldehyde (44) with potassium acetate, acetic aci...
Scheme 11: Synthesis of phthalide (50) by photoinduced decatungstate catalysis.
Scheme 12: Synthesis of woody acetate (54) by reduction of cyclohexanone 51 and subsequent acetylation; ADH200...
Scheme 13: Synthesis of juniper lactone (56) by pyrolysis of triperoxide 55 generated by oxidation of cyclohex...
Scheme 14: Synthesis of macrocyclic olefine 60 by ring-closing metathesis of diene 58 in a continuously stirre...
Scheme 15: Synthesis of macrocycles 65 and 66 by ring-closing metathesis of dienes 62 or 63, respectively, in ...
Scheme 16: Z-Selective synthesis of civetone (69) enabled by metathesis catalyst 68 in a tube-in-tube reactor.
Scheme 17: Synthesis of macrocyclic olefine 72 by ring-closing metathesis of diene 70.
Photoswitches beyond azobenzene: a beginner’s guide
- Michela Marcon,
- Christoph Haag and
- Burkhard König
Beilstein J. Org. Chem. 2025, 21, 1808–1853, doi:10.3762/bjoc.21.143
Graphical Abstract
Figure 1: Energy diagram of a two-state photoswitch. Figure 1 was redrawn from [2].
Figure 2: Example of the absorption spectra of the isomers of a photoswitch with most efficient irradiation w...
Scheme 1: Photoswitch classes described in this review.
Figure 3: Azoheteroarenes.
Scheme 2: E–Z Isomerisation (top) and mechanisms of thermal Z–E isomerisation (bottom).
Scheme 3: Rotation mechanism favoured by the electron displacement in push–pull systems. Selected examples of...
Figure 4: A) T-shaped and twisted Z-isomers determine the thermal stability and the Z–E-PSS (selected example...
Figure 5: Effect of di-ortho-substitution on thermal half-life and PSS.
Figure 6: Selected thermal lifetimes of azoindoles in different solvents and concentrations. aConcentration o...
Figure 7: Aryliminopyrazoles: N-pyrazoles (top) and N-phenyl (bottom).
Scheme 4: Synthesis of symmetrical heteroarenes through oxidation (A), reduction (B), and the Bayer–Mills rea...
Scheme 5: Synthesis of diazonium salt (A); different strategies of azo-coupling: with a nucleophilic ring (B)...
Scheme 6: Synthesis of arylazothiazoles 25 (A) and heteroaryltriazoles 28 (B).
Scheme 7: Synthesis of heteroarylimines 31a,b [36-38].
Figure 8: Push–pull non-ionic azo dye developed by Velasco and co-workers [45].
Scheme 8: Azopyridine reported by Herges and co-workers [46].
Scheme 9: Photoinduced phase transitioning azobispyrazoles [47].
Figure 9: Diazocines.
Scheme 10: Isomers, conformers and enantiomers of diazocine.
Scheme 11: Partial overlap of the ππ* band with electron-donating substituents and effect on the PSS. Scheme 11 was ada...
Figure 10: Main properties of diazocines with different bridges. aMeasured in n-hexane [56]. bMeasured in THF. cMe...
Scheme 12: Synthesis of symmetric diazocines.
Scheme 13: Synthesis of asymmetric diazocines.
Scheme 14: Synthesis of O- and S-heterodiazocines.
Scheme 15: Synthesis of N-heterodiazocines.
Scheme 16: Puromycin diazocine photoswitch [60].
Figure 11: Indigoids.
Figure 12: The main representatives of the indigoid photoswitch class.
Scheme 17: Deactivation process that prevents Z-isomerisation of indigo.
Figure 13: Stable Z-indigo derivative synthesised by Wyman and Zenhäusern [67].
Figure 14: Selected examples of indigos with aliphatic and aromatic substituents [68]. Dashed box: proposed π–π in...
Scheme 18: Resonance structures of indigo and thioindigo involving the phenyl ring.
Scheme 19: Possible deactivation mechanism for 4,4'-dihydroxythioindigo [76].
Scheme 20: Effect of different heteroaryl rings on the stability and the photophysical properties of hemiindig...
Figure 15: Thermal half-lives of red-shifted hemithioindigos in toluene [79]. aMeasured in toluene-d8.
Scheme 21: Structures of pyrrole [81] and imidazole hemithioindigo [64].
Figure 16: Examples of fully substituted double bond hemithioindigo (left), oxidised hemithioindigos (centre),...
Scheme 22: Structure of iminothioindoxyl 72 (top) and acylated phenyliminoindolinone photoswitch 73 (bottom). ...
Scheme 23: (top) Transition states of iminothioindoxyl 72. The planar transition state is associated with a lo...
Scheme 24: Baeyer–Drewsen synthesis of indigo (top) and N-functionalisation strategies (bottom).
Scheme 25: Synthesis of hemiindigo.
Scheme 26: Synthesis of hemithioindigo and iminothioindoxyl.
Scheme 27: Synthesis of double-bond-substituted hemithioindigos.
Scheme 28: Synthesis of phenyliminoindolinone.
Scheme 29: Hemithioindigo molecular motor [85].
Figure 17: Arylhydrazones.
Scheme 30: Switching of arylhydrazones. Note: The definitions of stator and rotor are arbitrary.
Scheme 31: Photo- and acidochromism of pyridine-based phenylhydrazones.
Scheme 32: A) E–Z thermal inversion of a thermally stable push–pull hydrazone [109]. B) Rotation mechanism favoured...
Scheme 33: Effect of planarisation on the half-life.
Scheme 34: The longest thermally stable hydrazone switches reported so far (left). Modulation of thermal half-...
Figure 18: Dependency of t1/2 on concentration and hypothesised aggregation-induced isomerisation.
Figure 19: Structure–property relationship of acylhydrazones.
Scheme 35: Synthesis of arylhydrazones.
Scheme 36: Synthesis of acylhydrazones.
Scheme 37: Photoswitchable fluorophore by Aprahamian et al. [115].
Scheme 38: The four-state photoswitch synthesised by the Cigáň group [116].
Figure 20: Diarylethenes.
Scheme 39: Isomerisation and oxidation pathway of E-stilbene to phenanthrene.
Scheme 40: Strategies adapted to avoid E–Z isomerisation and oxidation.
Scheme 41: Molecular orbitals and mechanism of electrocyclisation for a 6π system.
Figure 21: Aromatic stabilisation energy correlated with the thermal stability of the diarylethenes [127,129].
Figure 22: Half-lives of diarylethenes with increasing electron-withdrawing groups [128,129].
Scheme 42: Photochemical degradation pathway promoted by electron-donating groups [130].
Figure 23: The diarylethenes studied by Hanazawa et al. [134]. Increased rigidity leads to bathochromic shift.
Scheme 43: The dithienylethene synthesised by Nakatani's group [135].
Scheme 44: Synthesis of perfluoroalkylated diarylethenes.
Scheme 45: Synthesis of 139 and 142 via McMurry coupling.
Scheme 46: Synthesis of symmetrical derivatives 145 via Suzuki–Miyaura coupling.
Scheme 47: Synthesis of acyclic 148, malonic anhydride 149, and maleimide derivatives 154.
Figure 24: Gramicidin S (top left) and two of the modified diarylethene derivatives: first generation (bottom ...
Scheme 48: Pyridoxal 5'-phosphate and its reaction with an amino acid (top). The analogous dithienylethene der...
Figure 25: Fulgides.
Scheme 49: The three isomers of fulgides.
Scheme 50: Thermal and photochemical side products of unsubstituted fulgide [150].
Figure 26: Maximum absorption λc of the closed isomer compared with the nature of the aromatic ring and the su...
Scheme 51: Possible rearrangement of the excited state of 5-dimethylaminoindolylfulgide [153].
Figure 27: Quantum yields of ring closure (ΦE→C) and E–Z isomerisation (ΦE→Z) correlated with the increasing s...
Scheme 52: Active (Eα) and inactive (Eβ) conformers (left) and the bicyclic sterically blocked fulgide 169 (ri...
Scheme 53: Quantum yield of ring-opening (ΦC→E) and E–Z isomerisation (ΦE→Z) for different substitution patter...
Scheme 54: Stobbe condensation pathway for the synthesis of fulgides 179, fulgimides 181 and fulgenates 178.
Scheme 55: Alternative synthesis of fulgides through Pd-catalysed carbonylation.
Scheme 56: Optimised synthesis of fulgimides [166].
Scheme 57: Photoswitchable FRET with a fulgimide photoswitch [167].
Scheme 58: Three-state fulgimide strategy by Slanina's group.
Figure 28: Spiropyrans.
Scheme 59: Photochemical (left) and thermal (right) ring-opening mechanisms for an exemplary spiropyran with a...
Figure 29: Eight possible isomers of the open merocyanine according to the E/Z configurations of the bonds hig...
Scheme 60: pH-Controlled photoisomerisation between the closed spiropyran 191-SP and the open E-merocyanine 19...
Scheme 61: Behaviour of spiropyran in water buffer according to Andréasson and co-workers [180]. 192-SP in an aqueo...
Scheme 62: (left box) Proposed mechanism of basic hydrolysis of MC [184]. (right box) Introduction of electron-dona...
Scheme 63: Photochemical interconversion of naphthopyran 194 (top) and spirooxazine 195 (bottom) photoswitches...
Scheme 64: Synthesis of spiropyrans and spirooxazines 198 and the dicondensation by-product 199.
Scheme 65: Alternative synthesis of spiropyrans and spirooxazines with indolenylium salt 200.
Scheme 66: Synthesis of 4’-substituted spiropyrans 203 by condensation of an acylated methylene indoline 201 w...
Scheme 67: Synthesis of spironaphthopyrans 210 by acid-catalysed condensation of naphthols and diarylpropargyl...
Scheme 68: Photoswitchable surface wettability [194].
Figure 30: Some guiding principles for the choice of the most suitable photoswitch. Note that this guide is ve...
Photocatalyzed elaboration of antibody-based bioconjugates
- Marine Le Stum,
- Eugénie Romero and
- Gary A. Molander
Beilstein J. Org. Chem. 2025, 21, 616–629, doi:10.3762/bjoc.21.49
Graphical Abstract
Figure 1: Representation of an antibody–drug conjugate. The antibody shown in this figure is from https://www...
Figure 2: a. Photoredox catalytic cycles; b. absorption spectrum of photosensitizers. Therapeutic window indi...
Figure 3: Graph representing the average number of publications focusing on photoredox chemistry applied to p...
Figure 4: Schematic procedure developed by Sato et al. on histidine photoinduced modification. The antibody s...
Figure 5: Schematic procedure of the divergent method developed by Sato et al. on histidine/tyrosine photoind...
Figure 6: Schematic procedure developed by Bräse et al. on photoinduced disulfide rebridging method.
Figure 7: Schematic procedure developed by Lang et al. on a photoinduced dual nickel photoredox-catalyzed app...
Figure 8: Schematic of the procedure developed by Chang et al. on photoinduced high affinity IgG Fc-binding s...
Figure 9: Potential advantages of photoredox chemistry for bioconjugation applied to antibodies. The antibody...
Figure 10: Representation of the photoinduced control of the DAR. The antibody shown in this figure is from ht...
Figure 11: Representation of a photoinduced control of multi-payloads ADC strategy. The antibody shown in this...
Total synthesis of (±)-simonsol C using dearomatization as key reaction under acidic conditions
- Xiao-Yang Bi,
- Xiao-Shuai Yang,
- Shan-Shan Chen,
- Jia-Jun Sui,
- Zhao-Nan Cai,
- Yong-Ming Chuan and
- Hong-Bo Qin
Beilstein J. Org. Chem. 2025, 21, 601–606, doi:10.3762/bjoc.21.47
Graphical Abstract
Figure 1: Representative sesquineolignan compounds.
Scheme 1: The first total synthesis of (±)-simonsol C by Banwell’s group.
Scheme 2: The second total synthesis of (±)-simonsol C developed by the Qin group.
Figure 2: Retrosynthetic analysis of (±)-simonsol C.
Scheme 3: Rapid access of the basic skeleton of (±)- simonsol C.
Scheme 4: Synthetic details to (±)-simonsol C.
