Faculty of Pharmaceutical Sciences, Hokkaido University, Sapporo 060-0812, Japan.
J Am Chem Soc. 2011 Jul 13;133(27):10386-9. doi: 10.1021/ja203824v. Epub 2011 Jun 16.
Rh(I)-catalyzed formal [6 + 2] cycloaddition of allenal 6 having an alkyne or alkene in a tether proceeded smoothly, giving 5-8- and 6-8-fused bicyclic ketone derivatives 7 in good to excellent yields. It was also found that cyclization of enantiomerically enriched (S)-6a (94% ee) gave cyclic ketone derivative (S)-7a in high yield with reasonable chirality transfer (86% ee). This result indicates that this cyclization proceeds through stereoselective formation of rhodacycle H' followed by insertion of a multiple bond.
Rh(I)-催化的偕二炔基烯丙醛 6 的[6 + 2]环加成反应，其中炔烃或烯烃在连接基团中，反应顺利进行，以良好到优异的收率得到 5-8-和 6-8-稠合双环酮衍生物 7。还发现，对映体富集的 (S)-6a（94%ee）的环化反应以合理的手性转移（86%ee）得到高收率的环状酮衍生物 (S)-7a。这一结果表明，该环化反应通过手性铑环 H'的立体选择性形成，然后插入多重键进行。
