Steric and Electronic Effects in Conformational Preferences of C1-Oxygenated Chiral Alkenes

Article abstract of DOI:10.1021/jo00112a012

A variable temperature NMR study shows that the benzyl protective group on the hydroxy function of a chiral allylic alcohol enhances the CH eclipsed from (I).On the other hand, various silyl ethers enhance the preference for the CO eclipsed conformer.However, when both the allylic R group and the hydroxy protective group are bulky (R = tert-butyl, P = TIPS), the staggered conformation of the chiral alkene becomes preferred.An acetate group does not have an apparent effect on the conformational preference of the protected allylic alcohol.These facts are explained in terms of steric and electronic interactions.