Iridium‐Catalyzed Asymmetric Hydrogenation of Unfunctionalized Enamines

Optically active tertiary amines are readily prepared by iridium‐catalyzed asymmetric hydrogenation of unfunctionalized enamines (see scheme). The best enantioselectivities with >90 % ee were obtained with N‐aryl‐ and N‐benzyl‐substituted enamines with a terminal double bond. The hydrogenation of enamines derived from cyclic ketones, which has not been reported yet with other catalysts, gave enantiomeric excesses of up to 87 %.

     

Reactions of benzimidazole-2-carbaldehyde with enamines

Benzimidazole-2-carbaldehyde reacts with 1-morpholinocyclohexene, 1-morpholinocyclopentene, and aminocrotonic ester upon heating to form 4a,11-dimorpholino-1,2,3,4,11,11a-hexahydro-4aH-indolo[1,2-a]benzimidazole, 2-(2-morpholino-4,5-dihydrofulvenyl)benzimidazole, and 4-(benzimidazol-2-yl)-3,5-diethoxycarbonyl-2,6-dimethyl-1,4-dihydropyridine, respectively. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 566–571, March, 1999.     

An efficient one-pot route to symmetrically and unsymmetrically substituted 1,4,7-triazacyclononanes also results in the isolation of a stable macrocyclic aminal

A one-pot methodology has been developed for the direct synthesis of symmetrically and unsymmetrically N-substituted derivatives of 1,4,7-triazacyclononane. In the course of these studies the unexpected eight-membered cyclic aminal 7 has been isolated via an acid-catalysed rearrangement of enamine 5.     

Synthesis of 1-morpholino-1-(phenylethynyl)cycloalkanes from enamines and phenylacetylene in the presence of Cu(I) halides

1-Morpholino-1-(phenylethynyl)cyclopentane and 1-morpholino-1-(phenylethynyl)cyclohexane were obtained by reactions of enamines, derivatives of cyclic ketones, with phenylacetylene in the presence of CuI. A scheme for catalysis by Cu(I) compounds with the intermediate formation of copper phenylacetylide and iminium salts was suggested.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 169–170, January, 1994.     

Regioselective phosphorylation of α-N-alkylamino ketones

General preparative methods for regioselective functionalization of α-amino ketones with organophosphorus reagents were developed. Stable phosphorylated derivatives of all their prototropic forms (α-amino ketones, α-hydroxy imines, and β-hydroxy enamines) were obtained for the first time. The relative thermodynamic stability sequence of α-amino ketones was found to be reversed upon their phosphorylation: O-substituted forms were more stable than N-substituted ones, in contrast to the equilibrium between the prototropic isomers. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 288—293, February, 2006.     

Trifluoromethylation and pentafluorophenylation of enamines

A reaction of enamines with Me₃SiCF₃ and Me₃SiC₆F₅ in the presence of carboxylic acids leading to α-CF₃-and α-C₆F₅-substituted amines has been studied. 3-Cyanobenzoic acid was found to be the optimal promoter of these reactions. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1466–1468, August, 2007.     

Condensed Isoquinolines. 18. Enamine Properties of Benzimidazo[1,2-b]isoquinolin-11(5H)-one in the Michael Reaction

The reaction of benzimidazo[1,2-b]isoquinolin-11(5H)-one with activated olefins has been studied. The derivatives of 3,10-dioxo-3H,10H-benzimidazo[1,2,3-ij]benzo[c][1,8]naphthyridine formed are the result of an initial Michael reaction at C₍₆₎ followed by intramolecular heterocyclization.     

Silylation as a new strategy of the use of aliphatic nitro compounds in organic synthesis

Silylation of aliphatic nitro compounds is considered as a versatile multistage process. Due to activation of the - and -carbon atoms of the initial nitro substrates, these reactions give rise to a series of products untypical of the traditional chemistry of nitro compounds. A new redox process proposed in the present study involves controlled incomplete reduction of the nitro group with simultaneous oxidation of the carbon skeleton of the initial aliphatic nitro compound.