Reactions of 5-alpha-hydroxy steroids. VII. The westphalen rearrangement of some 3-beta-substituted-6-beta-acetoxy-5-alpha-hydroxy cholestanes.
Abstract Product analyses and kinetic studies of the reactions of 3β-substituted-6β-acetoxy-5α-hydroxy cholestanes with H 2 SO 4 -Ac 2 O-AcOH reveal a marked dependence of the reactions upon the nature of the 3β-substituent.
Acid catalysed reactions of 5α-hydroxy-steroids—III : The westphalen rearrangement☆
A kinetic study of the Westphalen rearrangement has revealed that the reaction proceeds through a sulphate ester which gives rise to a C5 carbonium ion. The effect of the 6β-substituent on the course of the reaction is described.
An anionic inositol phosphate glycan pseudotetrasaccharide exhibits high insulin-mimetic activity in rat adipocytes.
Inositol phosphate glycan pseudotetrasaccharides consisting of man-(alpha1-6)-man-(alpha1-4)-glcN-(alpha,beta1-6)-myo-inositol-1,2-cyclic phosphate possessing a sulfate group at either O-6 (compounds 3alpha,beta) or O-2 (compounds 4alpha,beta) of the terminal mannose have been prepared. Compound 4alpha was able to stimulate lipogenesis in native rat adipocytes to 78% of the maximal insulin response (MIR) with an EC50 of 1.1 microM. The other compounds exhibited lower maximal stimulations (47-63% MIR) and higher EC50 values (9.5-10.6 microM).