A new method for the preparation of optically active five-membered cyclic carbonates bearing an unsaturated substituent via an enzymatic reaction is described. In the examination of the regiospecific recognition of PPL, dl-(E)-4-(1-octenyl)-1,3-dioxolan-2-one is hydrolyzed with higher enantioselectivity. The reaction is also applicable to the racemic (E)-4-[2-(alkoxycarbony)ethenyl]-1,3-dioxolane-2-one
Synthesis of Intermediates for the Lactone Moiety of Mevinic Acids via Tellurium Chemistry
作者:Archana Kumar、Donald C. Dittmer
DOI:10.1021/jo00096a017
日期:1994.8
Treatment of p-toluenesulfonates of epoxides of specific primary allylic alcohols with telluride ion, prepared in situ by reduction of relatively nontoxic elemental tellurium, installs the two key secondary alcohol functions that occur in the lactone part of the cholesterol-lowering drugs, compactin, mevinolin, and lovastatin. Since the epoxides of the primary allylic alcohol starting materials can be synthesized in optically active form by the Sharpless-Katsuki asymmetric epoxidation (SAE) process, the stereospecific telluride transposition can give optically active secondary allylic alcohols configured for maximum inhibition of cholesterol function.
Diastereofacial Selectivity in the Cycloaddition of Nitrones to (<i>E</i>)-γ-Oxygenated α,β-Unsaturated Esters
作者:Félix Busqué、Pedro de March、Marta Figueredo、Josep Font、Montserrat Monsalvatje、Albert Virgili、Ángel Álvarez-Larena、Juan F. Piniella
DOI:10.1021/jo960960x
日期:1996.1.1
The 1,3-dipolar cycloadditions of nitrones 1 and 2 to a series of 1,2-disubstituted electron-deficient olefins bearing an allylic stereocenter, 4-8, are reported. The synlanti stereochemistry of the major endo adducts may be rationalized through the Houk transition-state model, but the possibility of intramolecular hydrogen bonding must be taken into account. In the case of the minor exo adducts the syn stereochemistry always predominates.
Kumar Archana, Dittmer Donald C., J. Org. Chem, 59 (1994) N 17, S 4760-4764