Alcohol versus alcohol: A highly stereocontrolled synthesis of substituted morpholines is realized by means of gold‐catalyzed dehydrative allylic cyclization of diols (see scheme for one example; segphos = 5,5′‐bis[di(3,5‐di‐tert‐butyl‐4‐methyoxyphenyl)phosphine]‐4,4′‐bi‐1,3‐benzodioxole). The present methodology represents one of the few examples of enantioselective gold‐catalyzed transformations
Bi(OTf)3 as a Dual Role Catalyst. Synthesis of Substituted Morpholine Derivatives via Catalytic O-Allylation
作者:Gregory R. Cook、Ryuji Hayashi、Jin-A Park
DOI:10.3987/com-13-s(s)116
日期:——
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.