Okamoto Kazuhiro, Hayashi Tamio, Rawal Viresh H
Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo, Kyoto 606-8502, Japan.
Org Lett. 2008 Oct 2;10(19):4387-9. doi: 10.1021/ol801931v. Epub 2008 Sep 5.
Chiral dienes possessing the bicyclo[2.2.2]octadiene framework were prepared readily through the [4 + 2] cycloaddition of ( R)-alpha-phellandrene with methyl propiolate as the key step. Diene 9, substituted with a tertiary alcohol on one of the two double bonds, is prepared in just one step from the cycloadduct and is highly effective as a chiral ligand for rhodium-catalyzed asymmetric conjugate addition reactions, giving the corresponding addition products with higher enantioselectivity than other chiral dienes.
具有双环[2.2.2]辛二烯骨架的手性二烯可通过(R)-α-水芹烯与丙酸甲酯的[4 + 2]环加成反应作为关键步骤轻松制备。二烯9在两个双键之一上被叔醇取代,可从环加成产物一步制备得到,并且作为铑催化的不对称共轭加成反应的手性配体非常有效,与其他手性二烯相比,能以更高的对映选择性得到相应的加成产物。