Small rings through large templates: A two‐point binding of the substrate radicals to cationic titanocene templates is essential for the success of otherwise impossible 4‐exo cyclizations (see scheme; Bn=benzyl). The cyclobutanes are obtained in high stereoselectivity and can be additionally functionalized in a straightforward manner.
Highly enantioselective cyclization using cationic Rh(I) with chiral ligand
作者:Xiao-Ming Wu、Kazuhisa Funakoshi、Kiyoshi Sakai
DOI:10.1016/s0040-4039(00)60966-8
日期:1992.10
(>99% de) of 3R (or S) 3,4-disubstituted 4-pentenals into the corresponding 3,4-cis(or trans)-disubstituted cyclopentanone and highly enantioselective cyclization (>99% ee) of 4-substituted 4-pentenals into 3-substituted cyclopentanone were achieved by using cationic Rh+(BINAP)ClO4−.