182277-26-5Relevant articles and documents
The effects of the nature of catalyst and of the solvent on the stereoselectivity in amine-catalyzed asymmetric synthesis of substituted cyclohexa-1,3-dienes from prenal and monoesters of ylidenemalonic acids
Serebryakov,Nigmatov,Shcherbakov,Struchkova
, p. 82 - 90 (1998)
In the amine-catalyzed reactions of prenal with (Z)-5-methyl-2-(methoxycarbonyl)hexa-2,4-dienoic or (Z)-3-phenyl-2-(ethoxycarbonyl)prop-2-enoic acid chiral β-amino alcohols provide for higher enantiomeric purity of the resulting alkyl 4-methyl-6-(2-methylprop-1-enyl)- and 4-methyl-6-phenylcyclohexa-1,3-dienoates than that provided by related chiral amines without hydroxy group. The values of ee attained in nonpolar solvents are higher than those observed in the polar ones. Substituting stoichiometric amounts of a chiral 1-amino-3-methylbuta-1,3-diene for a combination of prenal with 0.1 equiv. of the corresponding chiral amine results in the products of much lower enantiomeric purity.
The effect of pressure on the diastereoselectivity of the reaction of prenal with monoalkyl ylidenemalonates catalysed by homochiral secondary amines
Serebryakov,Nigmatov,Shcherbakov
, p. 174 - 175 (2001)
The dienamine-mediated formation of 6-substituted cyclohexa-1,3-dienes from the title reactants catalysed by either (S)- or (R)-prolinol at 8 kbar proceeds with different net enantioselectivities depending on the structure of RCH=C(CO2H)CO2Alk to give a product with the same configuration as that obtained at atmospheric pressure (if R = Me2C=CH) or with a configuration opposite to the latter (if R = Ph); by contrast, with both dienophiles the sense of enantioselectivity does not change with pressure when (S)-α,α-diphenyl-2-pyrrolidinemethanol is used as the catalyst.
