Diastereoselective ene reactions of triazolinediones with chiral allylic alcohols. Evidence for a hydroxyl-enophile steering effect

Article abstract of DOI:10.1016/S0040-4039(98)00207-X

The ene reaction of PTAD with the chiral allylic alcohol 4-methyl-3- penten-2-ol exhibits high threo diastereoselectivity in non polar solvents, whereas in polar solvents the diastereoselectivity decreases substantially. The results are discussed in terms of a steering effect between the hydroxyl and the incoming enophile during the formation of the diastereomeric syn and anti aziridinium imide intermediates.