Bi(OTF)_3 AS A DUAL ROLE CATALYST. SYNTHESIS OF SUBSTITUTED MORPHOLINE DERIVATIVES VIA CATALYTIC O-ALLYLATION

摘要

The diastereoselective synthesis of cis-1,4-disubstituted morpholines has been accomplished in good to excellent yields via Bi(OTf)_3 catalyzed ring-closing O-allylation under mild conditions without the need for added base. The bismuth Lewis acid catalyst appeared to play two roles; the mild deprotection of a silyl ether and the Lewis acid activation of an allylic halide for mild nucelophilic cyclization. Substituted morpholines were obtained with diastereoselectivity ranging from 2:1 to >99:1.