9 article(s) from Heimgartner, Heinz
Graphical Abstract
Figure 1: Structures of exemplary benzo- and heteroaromatic fused 1,4-quinone drugs and natural products.
Scheme 1: First [3 + 2]-cycloaddition of 1,4-naphthoquinone (1a) with intermediate nitrile imine 2, generated...
Scheme 2: Selected applications of trifluoroacetonitrile imines 7 in the synthesis of S-containing 5- and 6-m...
Scheme 3: Synthesis of [3 + 2]-cycloadducts 9a–l derived from CF3-substituted nitrile imines 7a–h and 1,4-qui...
Figure 2: X-ray structure of 3-trifluoromethylpyrazole derivative 9d. The labeling scheme of the asymmetric u...
Scheme 4: Thermal elimination of MeOH from the initial [3 + 2]-cycloadduct of 1d and nitrile imine 7d generat...
Scheme 5: Formation of the thermally stable, initially formed [3 + 2]-cycloadduct 10c obtained from 1e and ni...
Figure 3: Electronic absorption spectra for selected a) naphthoquinone-derived (9c, 9d, 9g) and b) anthraquin...
Graphical Abstract
Scheme 1: Synthesis of 2-unsubstituted imidazole N-oxides 1 from α-hydroxyiminoketones 2 and formaldimines 3.
Scheme 2: Preparation of adamantyloxyamine (4) and its conversion into N-(adamantyloxy)formaldimine (6a); Ad ...
Scheme 3: Synthesis of 1-(adamantyloxy)imidazole 3-oxides 7a–e and 1-adamantylimidazole 3-oxides 7f,g in acet...
Scheme 4: Deoxygenation of 1-(adamantyloxy)imidazole 3-oxides 7a–d and isomerization of 7b into imidazole-2-o...
Scheme 5: Conversions of imidazole 3-oxides 7a–d into 1-(adamantyloxy)imidazole-2-thiones 10a–d via sulfur tr...
Scheme 6: Syntheses of the non-symmetric 1,3-dialkoxyimidazolium bromides 13a–c and 1-alkyl-3-alkoxyimidazoli...
Scheme 7: Attempted O-adamantylation of imidazole N-oxide 7a with adamantan-1-yl trifluoroacetate and subsequ...
Scheme 8: Synthesis of the symmetric 1,3-di(adamantyloxy)imidazolium bromide (15) and its transformation to 1...
Graphical Abstract
Scheme 1: Reactions of aryl/hetarylthiochalcones 1a–d with 1,4-naphthoquinone (2b).
Scheme 2: Reactions of thiochalcones 1a–d with 1,4-anthraquinones 2c and 2d.
Figure 1: ORTEP plot [29] of the molecular structure of 4k showing the major conformation of the disordered thiop...
Figure 2: Products of the reactions of thiochalcones 1a and 1b with 1,4-benzoquinone (2a) and of 1a with mena...
Graphical Abstract
Figure 1: Dialkyl dicyanofumarates E-1 and dicyanomaleates Z-1.
Scheme 1: Methods for the synthesis of dialkyl dicyanofumarates E-1 from alkyl cyanoacetates 2.
Scheme 2: Methods for the synthesis of dialkyl dicyanofumarates E-1 from alkyl bromoacetates 3.
Scheme 3: Reaction of dimethyl dicyanofumarate (E-1b) with dimethoxycarbene [(MeO)2C:] generated in situ from...
Scheme 4: Cyclopropanation of diethyl dicyanofumarate (E-1a) through reaction with the thiophene derived sulf...
Scheme 5: Cyclopropanation of dimethyl dicyanofumarate (E-1b) through a stepwise reaction with the in situ ge...
Scheme 6: The [2 + 2]-cycloadditions of dimethyl dicyanofumarate (E-1b) with electron-rich ethylenes 20 and 22...
Scheme 7: The [2 + 2]-cycloaddition of isomeric dimethyl dicyanofumarate (E-1b) and dicyanomaleate (Z-1b) wit...
Scheme 8: Non-concerted [2 + 2]-cycloaddition between E-1b and bicyclo[2.1.0]pentene (27).
Scheme 9: Stepwise [3 + 2]-cycloadditions of some thiocarbonyl S-methanides with dialkyl dicyanofumarates E-1...
Scheme 10: Stepwise [3 + 2]-cycloadditions of dimethyl dicyanofumarate (E-1b) and dimethyl dicyanomaleate (Z-1b...
Scheme 11: [3 + 2]-Cycloaddition of diazomethane with dimethyl dicyanofumarate (E-1b) leading to 1H-pyrazole d...
Scheme 12: Reversible Diels–Alder reaction of fulvenes 36 with diethyl dicyanofumarate (E-1a).
Scheme 13: [4 + 2]-Cycloaddition of 9,10-dimethylanthracene (39b) and E-1a.
Scheme 14: Stepwise [4 + 2]-cycloaddition of dimethyl dicyanofumarate (E-1b) with electron-rich 1,1-dimethoxy-...
Scheme 15: Formal [4 + 2]-cycloaddition of 3,4-di(α-styryl)furan (47) with dimethyl dicyanofumarate (E-1b).
Scheme 16: Acid-catalyzed Michael addition of enolizable ketones of type 49 to E-1.
Scheme 17: Reaction of diethyl dicyanofumarate (E-1a) with ammonia NH3.
Scheme 18: Reaction of dialkyl dicyanofumarates E-1 with primary and secondary amines.
Scheme 19: Reaction of dialkyl dicyanofumarates E-1 with 1-azabicyclo[1.1.0]butanes 55.
Scheme 20: Formation of pyrazole derivatives in the reaction of hydrazines with E-1.
Scheme 21: Formation of 5-aminopyrazole-3,4-dicarboxylate 65 via heterocyclization reactions.
Scheme 22: Reactions of aryl- and hetarylcarbohydrazides 67 with E-1a.
Scheme 23: Multistep reaction leading to perhydroquinoxaline derivative 73.
Scheme 24: Synthesis of ethyl 7-aminopteridin-6-carboxylates 75 via a domino reaction.
Scheme 25: Synthesis of morhpolin-2-ones 80 from E-1 and β-aminoalcohols 78 through an initial aza-Michael add...
Scheme 26: Reaction of 3-amino-5-arylpyrazoles 81 with dialkyl dicyanofumarates E-1 via competitive nucleophil...
Scheme 27: Heterocyclization reaction of thiosemicarbazone 86 with E-1a.
Scheme 28: Formation of diethyl 4-cyano-5-oxotetrahydro-4H-chromene-3,4-dicarboxylate (90) from E-1a via heter...
Scheme 29: Reaction of dialkyl dicyanofumarates E-1 with cysteamine (92).
Scheme 30: Formation of disulfides through reaction of thiols with E-1a.
Scheme 31: Formation of CT salts of E-1 with Mn2+ and Cr2+ metallocenes through one-electron transfer.
Scheme 32: Oxidation of diethyl dicyanofumarate (E-1a) with H2O2 to give oxirane 101.
Scheme 33: The aziridination of E-1b through nitrene addition.
Graphical Abstract
Scheme 1: Reactions of diphenyl and phenyl selenophen-2-yl thioketones with diazomethane (CH2N2; Sel = seleno...
Scheme 2: Reaction of diaryl thioketones with trimethylsilyldiazomethane (TMS-CHN2).
Scheme 3: Formation of tetraaryl/hetarylethenes 9 from the reaction of TMS-CHN2 with diaryl/hetaryl thioketon...
Scheme 4: Synthesis of dibenzofulvenes 9g–k.
Scheme 5: a) Mechanistic explanation for formation of ethenes 9 from dithiolanes of type 6 and b) desilylatio...
Graphical Abstract
Scheme 1: Generation and typical reactions of the reactive dialkyl and diaryl thiocarbonyl S-methanides 1.
Figure 1: Structures of the reactive intermediates as a diradical 6 or a zwitterion 7 in the course of the di...
Scheme 2: The in situ generation of phenyl selenophen-2-yl S-methanide (8) and its competitive reactions: 1,3...
Figure 2: Potential 1,3-dipolar electrocyclization of thiocabonyl S-methanide 8A. Computed enthalpies (free e...
Figure 3: Stepwise radical dimerization of the reactive thiocarbonyl S-methanide 8. Computed enthalpies (free...
Figure 4: Potential competitive cyclization reactions of the intermediate diradical 12.
Figure 5: a) Spin densities in the conformers 12F and 12G of diradical 12. b) Heteroatom effect on the magnit...
Graphical Abstract
Scheme 1: Reactions of aromatic thiocarbonyl S-methanides 2a,b with ferrocenyl thioketones 1 (Table 1).
Figure 1: ORTEP Plot [16] of the molecular structures of the ferrocenyl-substituted 1,3-dithiolanes 5b and 5f (wi...
Scheme 2: Reactions of cycloaliphatic thiocarbonyl S-methanides with ferrocenyl hetaryl thioketones 1 (Table 1).
Scheme 3: Reaction of 3c with ferrocenyl methyl thioketone 1e.
Scheme 4: Mesomeric stabilization of the 1,5-diradical intermediate in the reaction of aromatic thiocarbonyl S...
Graphical Abstract
Scheme 1: ‘Head-to-head dimerization’ of diarylthioketone S-methanides 3a,b leading to 2,2,3,3-tetrasubstitut...
Scheme 2: Diradical nature of the reactive intermediate 3c in the reaction of phenyl selenophen-2-yl thioketo...
Scheme 3: Formation of thiiranes 8 and/or 1,3-dithiolanes 10 in the reaction of aryl/aryl, aryl/hetaryl and d...
Scheme 4: Proposed competitive mechanisms in the reactions of aryl/hetaryl and dihetaryl thioketones 1 with 2...
Graphical Abstract
Scheme 1: Hetero-Diels–Alder reaction of thiobenzophenone (1a) with dimethyl acetylenedicarboxylate (2a) [10].
Scheme 2: Synthesis of polycyclic thiopyrans via the hetero-Diels–Alder reaction/1,3-hydrogen shift sequence.
Figure 1: ORTEP Plot [19] of the molecular structure of 4b, drawn using 50% probability displacement ellipsoids.
Scheme 3: Reactions of aryl/hetaryl thioketones with methyl propiolate (Table 1).
Scheme 4: Oxidation of selected thiopyrans 4 and 5 to give the corresponding sulfones.
Figure 2: ORTEP Plot [19] of the molecular structure of one of the symmetry-independent molecules of 6d, drawn us...