Acetaldehyde in the Enders triple cascade reaction via acetaldehyde dimethyl acetal

• Alessandro Brusa,
• Debora Iapadre,
• Maria Edith Casacchia,
• Alessio Carioscia,
• Giuliana Giorgianni,
• Giandomenico Magagnano,
• Fabio Pesciaioli and
• Armando Carlone

Beilstein J. Org. Chem. 2023, 19, 1243–1250, doi:10.3762/bjoc.19.92

• simple flash chromatography. Conclusion An unprecedented methodology for the synthesis of 4,6-disubstituted 5-nitrocyclohexene carbaldehydes with three contiguous stereogenic centers using acetaldehyde as one of the reaction components of an Enders cascade reaction has been developed. The masked form of

• enantiomeric excesses. Unfortunately, the developed methodology is currently limited to aromatic substrates and the formation of one stereocenter is difficult to control, leading to a mixture of two diastereomers. Current efforts in our laboratories are addressing these challenges. Approaches based on the

Unravelling a trichloroacetic acid-catalyzed cascade access to benzo[f]chromeno[2,3-h]quinoxalinoporphyrins

• Chandra Sekhar Tekuri,
• Pargat Singh and
• Mahendra Nath

Beilstein J. Org. Chem. 2023, 19, 1216–1224, doi:10.3762/bjoc.19.89

• Chandra Sekhar Tekuri Pargat Singh Mahendra Nath Department of Chemistry, Faculty of Science, University of Delhi, Delhi 110 007, India 10.3762/bjoc.19.89 Abstract A facile one-pot four-component synthetic methodology is evolved to construct novel copper(II) benzo[f]chromeno[2,3-h

Exploring the role of halogen bonding in iodonium ylides: insights into unexpected reactivity and reaction control

• Carlee A. Montgomery and
• Graham K. Murphy

Beilstein J. Org. Chem. 2023, 19, 1171–1190, doi:10.3762/bjoc.19.86

• was first reported in 2010 [133], the subsequent collection of works by Vasdev and Liang led to an improved methodology appropriate for the time and temperature requirements of radiofluorination reactions, and led to a mechanistic proposal dependent on σ-hole selective halogen bonding [134]. Vasdev

Selective and scalable oxygenation of heteroatoms using the elements of nature: air, water, and light

• Damiano Diprima,
• Hannes Gemoets,
• Stefano Bonciolini and
• Koen Van Aken

Beilstein J. Org. Chem. 2023, 19, 1146–1154, doi:10.3762/bjoc.19.82

• negligible depending on the concentration of water. Conclusion A catalyst-free methodology for the selective oxygenation of heteroatoms (S, P, Se) has been developed using only air, water, and light. The protocol allows high conversion and excellent selectivity for a wide scope of substrates, with relative

Photoredox catalysis harvesting multiple photon or electrochemical energies

• Mattia Lepori,
• Simon Schmid and
• Joshua P. Barham

Beilstein J. Org. Chem. 2023, 19, 1055–1145, doi:10.3762/bjoc.19.81

Synthesis of imidazo[4,5-e][1,3]thiazino[2,3-c][1,2,4]triazines via a base-induced rearrangement of functionalized imidazo[4,5-e]thiazolo[2,3-c][1,2,4]triazines

• Dmitry B. Vinogradov,
• Alexei N. Izmest’ev,
• Angelina N. Kravchenko,
• Yuri A. Strelenko and
• Galina A. Gazieva

Beilstein J. Org. Chem. 2023, 19, 1047–1054, doi:10.3762/bjoc.19.80

• ][1,2,4]triazine or imidazo[4,5-e]thiazolo[2,3-c][1,2,4]triazine and the expansion of the thiazolidine ring to a thiazine core. The methodology proved to be effective for the preparation of a series of target compounds with different substituents in the tricyclic fragment. Examples of natural and

Aromatic C–H bond functionalization through organocatalyzed asymmetric intermolecular aza-Friedel–Crafts reaction: a recent update

• Anup Biswas

Beilstein J. Org. Chem. 2023, 19, 956–981, doi:10.3762/bjoc.19.72

• 2004. In this methodology, a 1,1’-bi-2-naphthol (BINOL)-derived chiral phosphoric acid P1 was used as the catalytic reagent to couple 2-methoxyfuran (1) and N-Boc-protected aldimines 2 to incorporate an aza-tertiary stereocenter into the 2’ position of the heteroaromatic products 3 (Scheme 1) [24

• -substituted indoles which effectively attacked the electrophile through the C2 position. The reaction was even compatible with pyrroles (Scheme 7a). The utility of this methodology was successfully demonstrated by the synthesis of product 23a, the key intermediate of natural product (+)-trigonoliimine (Scheme

• in the aryl ring of the imines whereas amenability of this methodology was narrow for ring-substituted pyrroles and indoles (Scheme 15a) [40]. In the next year, the same research group reported another aza-Friedel–Crafts reaction between 4,7-dihydroindole (55) and N-unsubstituted trifluoromethylated

Clauson–Kaas pyrrole synthesis using diverse catalysts: a transition from conventional to greener approach

• Dileep Kumar Singh and
• Rajesh Kumar

Beilstein J. Org. Chem. 2023, 19, 928–955, doi:10.3762/bjoc.19.71

• . This methodology has been applied to diverse areas of chemistry, including natural product synthesis [45][46], medicinal chemistry [47][48], polymer chemistry [49][50] and porphyrin chemistry [51][52][53]. In recent years, green chemistry has become a widely used method for organic synthesis in order

Asymmetric tandem conjugate addition and reaction with carbocations on acylimidazole Michael acceptors

• Brigita Mudráková,
• Renata Marcia de Figueiredo,
• Jean-Marc Campagne and
• Radovan Šebesta

Beilstein J. Org. Chem. 2023, 19, 881–888, doi:10.3762/bjoc.19.65

• organoboron reagents were realized [12]. Also, in terms of suitable Michael acceptors as substrates, unsaturated ketones, aldehydes, esters, thioesters, amides, alkenyl heterocycles and enoyl heterocycles became viable for conjugate additions. The maturity and robustness of this methodology is documented by

• control of RNA [16]. Moreover, Campagne and co-workers showed that Cu–NHC-catalyzed conjugate additions of dialkylzinc reagents proceed with high enantioselectivities [17][18][19]. Furthermore, this methodology allows iterative access to 1,3-disubstituted motifs that are present in various natural

• a tandem reaction comprising the Cu–NHC-catalyzed addition of dialkylzinc reagents to enoyl imidazoles followed by a trapping reaction with various onium compounds (Scheme 1). In this work we show the development of this methodology and its application to a range of acylimidazoles and carbocations

Pyridine C(sp²)–H bond functionalization under transition-metal and rare earth metal catalysis

• Haritha Sindhe,
• Malladi Mounika Reddy,
• Karthikeyan Rajkumar,
• Akshay Kamble,
• Amardeep Singh,
• Anand Kumar and
• Satyasheel Sharma

Beilstein J. Org. Chem. 2023, 19, 820–863, doi:10.3762/bjoc.19.62

• activation of 9 provides the hydroxy copper species 169, which on deoxygenative elimination furnishes the desired product 167. C-3 Heteroarylation In 2013, Su and co-workers [103] developed a catalytic methodology for the distal heteroarylation of pyridines 170 via Rh(III)-catalyzed dehydrogenative cross

Facile access to 3-sulfonylquinolines via Knoevenagel condensation/aza-Wittig reaction cascade involving ortho-azidobenzaldehydes and β-ketosulfonamides and sulfones

• Ksenia Malkova,
• Andrey Bubyrev,
• Stanislav Kalinin and
• Dmitry Dar’in

Beilstein J. Org. Chem. 2023, 19, 800–807, doi:10.3762/bjoc.19.60

• leading to 2-alkoxyquinolines. Compounds 5l an 5q were obtained in 63 and 51% yield, respectively (Scheme 3). It is worth noticing that chromenopyridine-3-sulfonamide 5h derived from heterocyclic azidoaldehyde 1h was also successfully synthesized following the methodology designed. Some limitations on the

Honeycomb reactor: a promising device for streamlining aerobic oxidation under continuous-flow conditions

• Masahiro Hosoya,
• Yusuke Saito and
• Yousuke Horiuchi

Beilstein J. Org. Chem. 2023, 19, 752–763, doi:10.3762/bjoc.19.55

• , conversion, yield and availability of the catalysts. Because the honeycomb reactor is made of porous material, the homogeneous reaction solution is a key factor. Stahl and Steves have developed a highly reactive aerobic oxidation [38]. This promising methodology enables completion of the reaction in 30 min

Enolates ambushed – asymmetric tandem conjugate addition and subsequent enolate trapping with conventional and less traditional electrophiles

• Péter Kisszékelyi and
• Radovan Šebesta

Beilstein J. Org. Chem. 2023, 19, 593–634, doi:10.3762/bjoc.19.44

• using acyclic enones 14 [27]. Their tandem conjugate addition/Mannich reaction methodology offers access to various non-cyclic β-aminoketones 16 with multiple contiguous stereocenters in high diastereo- and enantioselectivity (Scheme 5a). Additionally, chiral isoindolinones 18 and 2,3,4-trisubstituted

• azetidines 19 were also synthesized using this methodology (Scheme 5b). Nitronate anions were also found suitable for Mannich-type trapping reactions [28][29]. Anderson and co-workers accomplished several Cu-catalyzed conjugate additions of R2Zn to nitroolefins 20, followed by subsequent reaction with p

• ligands is that they can also promote the conjugate additions of aryl-based or branched Grignard reagents (Scheme 17) [49]. Further extending this methodology, we have investigated formaldehyde imine equivalents. These kinds of imines are not readily available, but they are highly important synthetic

Direct C2–H alkylation of indoles driven by the photochemical activity of halogen-bonded complexes

• Martina Mamone,
• Giuseppe Gentile,
• Jacopo Dosso,
• Maurizio Prato and
• Giacomo Filippini

Beilstein J. Org. Chem. 2023, 19, 575–581, doi:10.3762/bjoc.19.42

• to photochemically generate electrophilic radicals that can drive the functionalization of suitable electron-rich substrates [23]. Exploiting this strategy, here we report a novel metal-free methodology for the direct homolytic aromatic substitution (HAS) reaction of indoles 1 with α-iodosulfones 2

Phenanthridine–pyrene conjugates as fluorescent probes for DNA/RNA and an inactive mutant of dipeptidyl peptidase enzyme

• Josipa Matić,
• Tana Tandarić,
• Marijana Radić Stojković,
• Filip Šupljika,
• Zrinka Karačić,
• Ana Tomašić Paić,
• Lucija Horvat,
• Robert Vianello and
• Lidija-Marija Tumir

Beilstein J. Org. Chem. 2023, 19, 550–565, doi:10.3762/bjoc.19.40

• further supported by the fact that using the same methodology, the isolated phenanthridine showed an absorption maximum of 256 nm at pH 7.0, which is in perfect agreement with the experimental value of 248 nm [34] and well-matched with 250 nm reported here for Phen-AA (Table 1). Interactions of Phen-Py-1

Transition-metal-catalyzed domino reactions of strained bicyclic alkenes

• Austin Pounder,
• Eric Neufeld,
• Peter Myler and
• William Tam

Beilstein J. Org. Chem. 2023, 19, 487–540, doi:10.3762/bjoc.19.38

• sketched in red, with newly formed cyclic structures being highlighted. Review Earth-abundant metals Among the transition metal used in organic synthesis, the late transition metals like rhodium, palladium, and iridium have taken center stage when it comes to methodology development. Although these late

• equivalents of water interrupted the cyclization step and led entirely to reductively coupled alkenylated ring-opened products. Interestingly, when this methodology was applied to the ester-bearing oxabicyclic 1a, the anticipated reductive coupling product was not detected; instead, bicyclic γ-lactone 4 was

• oxanorbornenes; however, the latter two substrates did not undergo dehydrogenation, generating cis-selective annulated coumarins (10b and 10d). In 2006, the same group applied this methodology for the total synthesis of arnottin I (10h), a coumarin-type natural product isolated from the bark of the Xanthoxylum

Total synthesis: an enabling science

• Bastien Nay

Beilstein J. Org. Chem. 2023, 19, 474–476, doi:10.3762/bjoc.19.36

• synthetic methodology developments and to natural product isolation or biosynthesis. Thus, thematic issues dealing with total synthesis in the Beilstein Journal of Organic Chemistry have naturally been published in these fields, such as "Transition-metal and organocatalysis in natural product synthesis

Transition-metal-catalyzed C–H bond activation as a sustainable strategy for the synthesis of fluorinated molecules: an overview

• Louis Monsigny,
• Floriane Doche and
• Tatiana Besset

Beilstein J. Org. Chem. 2023, 19, 448–473, doi:10.3762/bjoc.19.35

• aryl residue allowed the monofunctionalization to occur selectively. Also, amide 1g bearing a disubstituted arene was successfully functionalized in 59% yield. Finally, the difunctionalized thiophene derivative 2h was obtained in 56% yield. In 2016, Wang's group developed another methodology for the

• 2014, Shen and Xu [117] developed a new methodology for the selective functionalization of 2-arylpyridine derivatives using an electrophilic SCF3 reagent, the Haas reagent I (Scheme 5) [118]. A broad range of 2-arylpyridine derivatives were trifluoromethylthiolated in good to high yields (18 examples

• desired trifluoromethylthiolated product 12 is selectively afforded after a F/SCF3 ligand exchange. In 2015, Ye and Liu reported the palladium-catalyzed trifluoromethylthiolation of 2-arylpyridine derivatives using the Billard reagent II (Scheme 7) [120]. Unlike Shen's methodology (Scheme 5), the use of

CuAAC-inspired synthesis of 1,2,3-triazole-bridged porphyrin conjugates: an overview

• Dileep Kumar Singh

Beilstein J. Org. Chem. 2023, 19, 349–379, doi:10.3762/bjoc.19.29

• ], nanoscience [12], and materials research [13][14]. Moreover, this review describes the use of the click methodology for the construction of various β- and meso-substituted 1,2,3-triazoloporphyrins by using azide or alkyne-substituted porphyrin as substrate (Figure 2). Every example mentioned in this review

• protected α-propargylglucose 42a or mannose 42b in the presence of CuCl in a toluene/H2O (4:1) (Scheme 7). Further a fully deprotected mannosyl residue 42c was also introduced via "click reaction”, yielding the glycoporphyrin 43c. Moreover, this methodology can also be utilized to introduce various

An efficient metal-free and catalyst-free C–S/C–O bond-formation strategy: synthesis of pyrazole-conjugated thioamides and amides

• Shubham Sharma,
• Dharmender Singh,
• Sunit Kumar,
• Vaishali,
• Rahul Jamra,
• Naveen Banyal,
• Deepika,
• Chandi C. Malakar and
• Virender Singh

Beilstein J. Org. Chem. 2023, 19, 231–244, doi:10.3762/bjoc.19.22

• synthetic flexibility of this methodology, we employed pyrazole C-5 carbaldehydes 9 and 10 for the synthesis of thioamide conjugates. It was noticed that the pyrazole-5-carbaldehydes 9 and 10 were more reactive as compared to pyrazole C-3 and C-4 carbaldehydes, leading to the formation of products 9C and

• 4F in good yields (61 and 70%), whereas, in the case of 5-nitro-2-aminopyridine (G), the anticipated product 1G was obtained in low yield (34%). To check the synthetic versatility of this oxidative amidation approach, we tested the scope of the methodology with pyrazole-5-carbaldehydes 9 and 10

• , and good to excellent yields of the desired molecules. Moreover, a practical synthetic utility of pyrazole-3/5-carbaldehydes has been explored through the formation of amide bond-tethered pyrazole-pyridine conjugates. This developed methodology was successfully carried out by employing commercially

Sequential hydrozirconation/Pd-catalyzed cross coupling of acyl chlorides towards conjugated (2E,4E)-dienones

• Benedikt Kolb,
• Daniela Silva dos Santos,
• Sanja Krause,
• Anna Zens and
• Sabine Laschat

Beilstein J. Org. Chem. 2023, 19, 176–185, doi:10.3762/bjoc.19.17

• ]. Since the early work by Wailes, Schwartz and Buchwald on the Schwartz reagent Cp2Zr(H)Cl and its reactivity towards alkynes, alkenes, and C–X double bonds particularly hydrozirconation has gained much attention [25][26][27][28][29][30]. It has been successfully employed in methodology studies [31][32

Practical synthesis of isocoumarins via Rh(III)-catalyzed C–H activation/annulation cascade

• Qian-Ci Gao,
• Yi-Fei Li,
• Jun Xuan and
• Xiao-Qiang Hu

Beilstein J. Org. Chem. 2023, 19, 100–106, doi:10.3762/bjoc.19.10

• , methyl, and phenyl groups underwent the current reaction efficiently, delivering the desired products 3ab–ae in moderate to good yields (43–93%). To demonstrate the synthetic utility of this methodology, a gram-scale synthesis of isocoumarin 3ia was firstly performed. Under the optimal conditions, the

• and diverse functionalization of the isocoumarin products highlight the tremendous synthetic potential of this methodology in chemical synthesis and drug discovery. Experimental A 10 mL screw-cap vial was charged with enaminone 1 (0.2 mmol), iodonium ylide 2 (0.6 mmol), [Cp*RhCl2]2 (6.2 mg, 5 mol

Redox-active molecules as organocatalysts for selective oxidative transformations – an unperceived organocatalysis field

• Elena R. Lopat’eva,
• Igor B. Krylov,
• Dmitry A. Lapshin and
• Alexander O. Terent’ev

Beilstein J. Org. Chem. 2022, 18, 1672–1695, doi:10.3762/bjoc.18.179

• Elena R. Lopat'eva Igor B. Krylov Dmitry A. Lapshin Alexander O. Terent'ev N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Leninsky Prospect 47, Moscow, 119991, Russia 10.3762/bjoc.18.179 Abstract Organocatalysis is widely recognized as a key synthetic methodology in

• include their synthetic availability, wide opportunities for rational structure design, generally lower toxicity, air and water stability, metal-free nature, and the scalability of their production and use. These features have made organocatalysis a prospering area and an even more promising methodology

Rhodium-catalyzed intramolecular reductive aldol-type cyclization: Application for the synthesis of a chiral necic acid lactone

• Motoyuki Isoda,
• Kazuyuki Sato,
• Kenta Kameda,
• Kana Wakabayashi,
• Ryota Sato,
• Hideki Minami,
• Yukiko Karuo,
• Atsushi Tarui,
• Kentaro Kawai and
• Masaaki Omote

Beilstein J. Org. Chem. 2022, 18, 1642–1648, doi:10.3762/bjoc.18.176

• described to give β-hydroxylactones with high diastereoselectivities. The stereoselectivity of this cyclization is highly solvent dependent and can give syn- or anti-β-hydroxylactones with high diastereoselectivity. This methodology was also applied to the synthesis of a chiral necic acid lactone which is a

Synthesis of (−)-halichonic acid and (−)-halichonic acid B

• Keith P. Reber and
• Emma L. Niner

Beilstein J. Org. Chem. 2022, 18, 1629–1635, doi:10.3762/bjoc.18.174

• [7], we viewed the halichonic acids as ideal targets to extend the scope of our synthetic methodology. Given the structural similarity between compounds (+)-1 and (+)-2 (and the fact that they were co-isolated from the same sponge), Tsukamoto et al. proposed that these natural products could be