Chen Tao, Gan Lifei, Wang Ran, Deng Yuhua, Peng Fangzhi, Lautens Mark, Shao Zhihui
Key Laboratory of Medicinal Chemistry for Natural Resource, Ministry of Education, School of Chemical Science and Technology, State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, Yunnan University, Kunming, 650091, China.
Davenport Laboratories, Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, ON, M5S 3H6, Canada.
Angew Chem Int Ed Engl. 2019 Oct 28;58(44):15819-15823. doi: 10.1002/anie.201909596. Epub 2019 Sep 19.
The strong binding ability of P-ylides with transition metals limits the utilization of stabilized P-ylide as nucleophiles in asymmetric organometallic catalysis. Herein we describe the first rhodium-catalyzed asymmetric ring-opening reaction of P-ylides utilizing oxabicyclic alkenes as the electrophilic partner. Various P-ylides including ester-, ketone- and amide-style P-ylides are all applicable. This asymmetric reaction occurs through the cleavage of two bridgehead C-O bonds and the formation of two C-C bonds, and oxabenzonorbornadienes are used as 1,4-biselectrophiles, thus providing access to benzonorcaradienes in good yields with high enantioselectivity and perfect diastereoselectivity. The present protocol also constitutes the first highly enantioselective direct catalytic asymmetric cyclopropanation of stabilized P-ylide nucleophiles.
磷叶立德与过渡金属的强结合能力限制了稳定化磷叶立德作为亲核试剂在不对称有机金属催化中的应用。在此，我们报道了首例以氧杂双环烯烃作为亲电试剂的铑催化磷叶立德不对称开环反应。各种磷叶立德，包括酯型、酮型和酰胺型磷叶立德均适用。该不对称反应通过两个桥头碳-氧键的断裂和两个碳-碳键的形成进行，氧杂苯并降冰片二烯用作1,4-双亲电试剂，从而以良好的产率、高对映选择性和完美的非对映选择性得到苯并降蒈二烯。本方法还构成了首例稳定化磷叶立德亲核试剂的高度对映选择性直接催化不对称环丙烷化反应。
