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Search for "structure–reactivity relationships" in Full Text gives 4 result(s) in Beilstein Journal of Organic Chemistry.
Eschenmoser coupling reactions starting from primary thioamides. When do they work and when not?
- Lukáš Marek,
- Jiří Váňa,
- Jan Svoboda and
- Jiří Hanusek
Beilstein J. Org. Chem. 2023, 19, 808–819, doi:10.3762/bjoc.19.61
- synthesis; isoquinolin-4-ones; primary thioamides; structure–reactivity relationships; Introduction During several past years, we have developed [1][2] a novel synthetic approach toward (Z)-3-[amino(phenyl/methyl)methylidene]-1,3-dihydro-2H-indol-2-ones and have demonstrated [3][4] its application
Graphical Abstract
Scheme 1: Eschenmoser coupling reaction between 3-substituted oxindoles and thioamides.
Scheme 2: Possible reactions of α-haloketones, esters and amides with primary thioamides.
Figure 1: Studied α-bromoamides and α-bromolactams.
Scheme 3: Reaction of 4-bromo-1,1-dimethyl-1,4-dihydroisoquinolin-3(2H)-one (2b) with thiobenzamide and thioa...
Scheme 4: Reaction of 4-bromo-1,1-dimethyl-1,4-dihydroisoquinolin-3(2H)-one (2b) with 4’-substituted thiobenz...
Scheme 5: Reaction of 4-bromoisoquinoline-1,3(2H,4H)-dione (3) with thiobenzamide, thioacetamide, and thioben...
Scheme 6: Reaction of N-phenyl- and N-methyl-2-bromo(phenyl)acetamide (4a,b) with thiobenzamide in acetonitri...
Scheme 7: Transformation of salt 15 under kinetic and thermodynamic control conditions [1].
Figure 2: Comparison of energy profiles (relative Gibbs energies at 298 K in kJ·mol−1 for the ECR (right) and...
Stereo- and regioselectivity of the hetero-Diels–Alder reaction of nitroso derivatives with conjugated dienes
- Lucie Brulíková,
- Aidan Harrison,
- Marvin J. Miller and
- Jan Hlaváč
Beilstein J. Org. Chem. 2016, 12, 1949–1980, doi:10.3762/bjoc.12.184
- reaction towards one regioisomer because of the activating effect and steric hindrance of the phosphonate substituent onto the butadienyl moiety. The computed activation barriers for the cycloaddition of 28 to some representative nitroso compounds 29 were used to elucidate the structure–reactivity
- relationships and to predict the regioselectivity. The results indicated that the nitroso dienophiles’ reactivity towards diene 28 increases from nitrosotoluene 29b and α-chloronitroso compound 29c to acylnitroso compounds 29d–g (Figure 3). In the same year, the Marchand–Brynaert group reported computational
Graphical Abstract
Scheme 1: Nitroso hetero-Diels–Alder reaction.
Scheme 2: The hetero-Diels–Alder reaction between thebaine (4) and an acylnitroso dienophile 5.
Figure 1: Examples of nitroso dienophiles frequently used in hetero-Diels–Alder reaction studies.
Scheme 3: Synthesis of arylnitroso species by substitution of a trifluoroborate group [36].
Scheme 4: Synthesis of arylnitroso compounds by amine oxidation.
Scheme 5: Synthesis of arylnitroso compounds by hydroxylamine oxidation.
Scheme 6: Synthesis of chloronitroso compounds by the treatment of a nitronate anion with oxalyl chloride.
Scheme 7: Non-oxidative routes to acylnitroso species.
Figure 2: RB3LYP/6-31G* computed energies (in kcal·mol−1) and bond lengths for exo and endo-transition states...
Scheme 8: Hetero-Diels–Alder cycloadditions of diene 28 and nitroso dienophiles 29.
Figure 3: Relative reactivity (ΔE#) and regioselectivity (Δ) for hetero-Diels–Alder of 28 and nitroso dienoph...
Scheme 9: Reaction of chiral 1-phosphono-1,3-butadiene 31 with nitroso dienophiles 32.
Scheme 10: Hetero-Diels–Alder reactions of hydroxamic acids 35 with various dienes 37.
Scheme 11: General regioselectivity of the nitroso hetero-Diels–Alder reaction observed with unsymmetrical die...
Scheme 12: Effect of the nitroso species on the regioselectivity for weakly directing 2-substituted dienes.
Scheme 13: Regioselectivity of 1,4-disubstituted dienes 51.
Scheme 14: Nitroso hetero-Diels–Alder reaction between Boc-nitroso compound 54 and dienes 55.
Scheme 15: Nitroso hetero-Diels–Alder reaction between Wightman reagent 58 and dienes 59.
Scheme 16: Regioselective reaction of 3-dienyl-2-azetidinones 62 with nitrosobenzene (47).
Scheme 17: The regioselective reaction of 1,3-butadienes 65 with various nitroso heterodienophiles 66.
Scheme 18: Catalysis of the nitroso hetero-Diels–Alder reaction by vanadium in the presence of the oxidant CHP...
Figure 4: 1,2-Oxazines synthesized in solution with moderate to high regioselectivity, showing the favored re...
Figure 5: 1,2-Oxazines synthesized in the solid phase with moderate to high regioselectivity, showing the fav...
Scheme 19: Regioselectivity of solution-phase nitroso hetero-Diels–Alder reaction with acyl and aryl nitroso d...
Scheme 20: Favored regioisomeric outcome for the solution and solid-phase reactions, giving hetero-Diels–Alder...
Figure 6: Favored regioisomers and regioisomeric ratios for 1,2-oxazines synthesized in solid phase (91, 93, ...
Scheme 21: Regiocontrol of the reaction between 3-dienyl-2-azetidinones and nitrosobenzene due to change in a ...
Scheme 22: Regiocontrol of the reaction between diene 111 and 2-methyl-6-nitrosopyridine (112) due to metal co...
Scheme 23: Asymmetric hetero-Diels–Alder reactions reported by Vasella [56].
Scheme 24: Asymmetric hetero-Diels–Alder reaction of cyclohexa-1,3-diene (120) with acylnitroso dienophile 119....
Scheme 25: Asymmetric induction with L-proline derivatives 124–126.
Scheme 26: Asymmetric cycloaddition of the acylnitroso compound 136 to diene 135.
Scheme 27: Asymmetric induction with arylmenthol-based nitroso dienophiles 142.
Scheme 28: Cycloaddition of silyloxycyclohexadiene 145 to the acylnitroso dienophile derived from (+)-camphors...
Scheme 29: Asymmetric reaction of O-isopropylidene-protected cis-cyclohexa-3,5-diene-1,2-diol 147 with mannofu...
Scheme 30: Synthesis of synthon 152 from 2-methoxyphenol 150 and chiral auxiliary 151.
Scheme 31: Asymmetric nitroso hetero-Diels–Alder reaction with Wightman chloronitroso reagent 58.
Scheme 32: Asymmetric 1,2-oxazine synthesis using chiral cyclic diene 157 and the application of this reaction...
Scheme 33: Asymmetric 1,2-oxazine synthesis using a chiral diene reported by Jones et al. [75]. aRegioisomeric rat...
Scheme 34: The nitroso hetero-Diels–Alder reaction of acyclic oxazolidine-substituted diene 170 and chiral 1-s...
Scheme 35: The nitroso hetero-Diels–Alder reaction of acyclic lactam-substituted diene 176 with various acylni...
Scheme 36: The hetero-Diels–Alder reaction of acylnitroso dienophile.
Scheme 37: The hetero-Diels–Alder reaction of arylnitroso dienophiles using Lewis acids.
Scheme 38: Asymmetric hetero-Diels–Alder reactions of chiral alkyl N-dienylpyroglutamates.
Scheme 39: Catalytic asymmetric arylnitroso reaction between mono-substituted 1,3-cyclohexadiene 196 and disub...
Figure 7: Plausible chelate intermediate complexes formed during the hetero-Diels–Alder reaction to give 1,2-...
Scheme 40: Catalytic asymmetric nitroso hetero-Diels–Alder between cyclic dienes and 2-nitrosopyridine.
Scheme 41: The reason for the increased enantioselectivity of stereoisomer 212 compared with stereoisomer 213.
Scheme 42: The copper-catalyzed nitroso hetero-Diels–Alder reaction of 6-methyl-2-nitrosopyridine (199) with p...
Scheme 43: Asymmetric nitroso hetero-Diels–Alder reaction of nitrosoarenes with dienylcarbamates catalyzed by ...
Scheme 44: The enantioselective hetero-Diels–Alder reaction between nitrosobenzene and (E)-2,4-pentadien-1-ol (...
Scheme 45: Asymmetric nitroso hetero-Diels–Alder reaction using tartaric acid ester chelation of the diene and...
New core-pyrene π structure organophotocatalysts usable as highly efficient photoinitiators
- Sofia Telitel,
- Frédéric Dumur,
- Thomas Faury,
- Bernadette Graff,
- Mohamad-Ali Tehfe,
- Didier Gigmes,
- Jean-Pierre Fouassier and
- Jacques Lalevée
Beilstein J. Org. Chem. 2013, 9, 877–890, doi:10.3762/bjoc.9.101
- r5 and r6 and (iv) the ability of Co_Py•+ to initiate a ring-opening polymerization process. Structure–reactivity relationships for the different derivatives can hardly be extracted. This is probably ascribed to a strong interplay between (i) to (iv). A cationic photopolymerization profile of EPOX
Graphical Abstract
Scheme 1: Typical reactions for photoinitiated cationic polymerization.
Scheme 2: Examples of previously investigated architectures.
Scheme 3: Investigated Co_Pys.
Scheme 4: Other chemical compounds.
Figure 1: UV–vis absorption spectra of the investigated compounds: (A) In acetonitrile for Py_1 and acetonitr...
Figure 2: HOMO–LUMO orbitals for Py_2, Py_3, Py_5, Py_6, Py_8, Py_11 and Py_12 involved in the π–π* transitio...
Figure 3: Fluorescence quenching of 1Py_3 by the phenacylbromide (PBr) in acetonitrile/toluene (50/50). Inser...
Scheme 5: Photochemical processes for the different Co_Pys.
Figure 4: ESR spectra obtained upon irradiation of (A) Py_3/Iod, (B) Py_3/PBr and (C) Py_3/EDB in tert-butylb...
Figure 5: ESR-spin trapping spectra of Py_9/Iod in tert-butylbenzene (storage at rt for 24 h); (a) experiment...
Figure 6: Photopolymerization profiles of EPOX upon Xe–Hg lamp irradiation (λ > 340 nm) under air for differe...
Figure 7: Photopolymerization profiles of EPOX upon a Xe–Hg lamp irradiation (λ > 340 nm) under air for diffe...
Figure 8: (A) Photopolymerization profiles of EPOX-Si upon a Xe–Hg lamp irradiation (λ > 340 nm) under air fo...
Figure 9: Photopolymerization profiles of TMPTA upon Xe–Hg lamp irradiation (λ > 340 nm) in laminate for diff...
Figure 10: Photolysis of (A) the Py_3/PBr couple, (B) the Py_3/Iod couple, and (C) the Py_3/MDEA couple; Xe–Hg...
Figure 11: Photolysis of (A) the Py_11/Iod and (B) the Py_11/Iod/NVK couple. Halogen lamp irradiation. In acet...
Scheme 6: The oxidative cycle.
Scheme 7: Oxidation versus reduction cycles.
A quantitative approach to nucleophilic organocatalysis
- Herbert Mayr,
- Sami Lakhdar,
- Biplab Maji and
- Armin R. Ofial
Beilstein J. Org. Chem. 2012, 8, 1458–1478, doi:10.3762/bjoc.8.166
- ; kinetics; NHC activation; organocatalysis; structure reactivity relationships; Review Introduction The most comprehensive nucleophilicity and electrophilicity scales presently available, are based on Equation 1, in which electrophiles are characterized by one solvent-independent parameter E, and
Graphical Abstract
Figure 1: Second-order rate constants for reactions of electrophiles with nucleophiles.
Figure 2: Mechanism of amine-catalyzed conjugate additions of nucleophiles [23-28].
Figure 3: Kinetics of the reactions of the iminium ion 3a with the silylated ketene acetal 7a [35].
Figure 4: Laser flash photolytic generation of iminium ions 3a.
Figure 5: Correlations of the reactivities of the iminium ions 3a and 3b toward nucleophiles with the corresp...
Figure 6: Comparison of the electrophilicities of cinnamaldehyde-derived iminium ions 3a–3i.
Figure 7: Nucleophiles used in iminium activated reactions [35,42,44-52].
Figure 8: Counterion effects in electrophilic reactions of iminium ions 3a-X (at 20 °C, silyl ketene acetal 7b...
Figure 9: Comparison of calculated and experimental rate constants of electrophilic aromatic substitutions wi...
Figure 10: Aza-Michael additions of the imidazoles 15 with the iminium ion 3a [58].
Figure 11: Plots of log k2 for the reactions of enamides 17a–17e with the benzhydrylium ions 18a–d in CH3CN at...
Figure 12: Comparison of the nucleophilicities of enamides 17 with those of several other C nucleophiles (solv...
Figure 13: Experimental and calculated rate constants k2 for the reactions of 17b and 17g with 3a and 3b in th...
Figure 14: Comparison between experimental and calculated (Equation 1) cyclopropanation rate constants [64].
Figure 15: Electrostatic activation of iminium activated cyclopropanations with sulfur ylides.
Figure 16: Sulfur ylides inhibit the formation of iminium ions.
Figure 17: Enamine activation [65].
Figure 18: Electrophilicity parameters E for classes of compounds that have been used as electrophilic substra...
Figure 19: Quantification of the nucleophilic reactivities of the enamines 32a–e in acetonitrile (20 °C) [83]; a d...
Figure 20: Proposed transition states for the stereogenic step in proline-catalyzed reactions.
Figure 21: Kinetic evidence for the anchimeric assistance of the electrophilic attack by the carboxylate group....
Figure 22: Differentiation of nucleophilicity and Lewis basicity (in acetonitrile at 20 °C): Rate (left) and e...
Figure 23: NHCs 41, 42, and 43 are moderately active nucleophiles and exceptionally strong Lewis bases (methyl...
Figure 24: Nucleophilic reactivities of the deoxy Breslow intermediates 45 in THF at 20 °C [107].
Figure 25: Comparison of the proton affinities (PA, from [107]) of the diaminoethylenes 47a–c with the methyl catio...
Figure 26: Berkessel’s synthesis of a Breslow intermediate (51, keto tautomer) from carbene 43 [112].
Figure 27: Synthesis of O-methylated Breslow intermediates [114].
Figure 28: Relative reactivities of deoxy- and O-methylated Breslow intermediates [114].
Figure 29: Reactivity scales for electrophiles and nucleophiles relevant for organocatalytic reactions (refere...
