A RATIONALLY DESIGNED CHIRAL AUXILIARY FOR HYDROXYALKYL RADICALS LEADS TO EXCEPTIONAL RHO-STEREOCONTROL

Substitution of a t-butyl group at C-6 of the THP ring results in a ch iral auxiliary that exerts exceptional stereocontrol in radical additi on reactions. For example, radical 2c adds to 2-nitropropene at -78 de grees C to give, after reductive hydrolysis, the protected aldol 4c wi th a diastereoselectivity of 35/1. Good selectivity (ds = 8/1) is even observed when the reaction is conducted at ambient temperature. (C) 1 997 Elsevier Science Ltd.