Stereoselectivity and Regioselectivity in the Segment-Coupling Prins Cyclization
作者:James J. Jaber、Kazuhiko Mitsui、Scott D. Rychnovsky
DOI:10.1021/jo010232w
日期:2001.6.1
allylic alcohols leads to fragmentation rather than a disfavored 5-endo-trig cyclization. Dienols in which one alkene is allylic and the other alkene is homoallylic cyclizeefficiently and produce the tetrahydropyrans 49-54, Table 3. Dienols with two homoallylic alkenes cyclize with modest to high regioselectively, generating tetrahydropyrans 40-45, Table 2. The relative rates for cyclization decrease