Enantioselective Phosphine-Catalyzed Formal [4+4] Annulation of α,β-Unsaturated Imines and Allene Ketones: Construction of Eight-Membered Rings
作者:Huanzhen Ni、Xiaodong Tang、Wenrui Zheng、Weijun Yao、Nisar Ullah、Yixin Lu
DOI:10.1002/anie.201707183
日期:2017.11.6
Magic eight “ring”: Under the catalysis of amino-acid-derived phosphines, the unprecedented [4+4] annulations between benzofuran/indole-derived α,β-unsaturated imines and allene ketones proceeded smoothly to afford azocines in excellent yields and with nearly perfect enantioselectivities. This work marks the first efficient asymmetric construction of optically enriched eight-membered rings by phosphine
Enantioselective Synthesis of Tetrahydropyridines/Piperidines via Stepwise [4 + 2]/[2 + 2] Cyclizations
作者:Zhen Wang、Huacheng Xu、Qin Su、Ping Hu、Pan-Lin Shao、Yun He、Yixin Lu
DOI:10.1021/acs.orglett.7b01221
日期:2017.6.16
A phosphine-catalyzed novel enantioselective [4 + 2]-annulation reaction between allene ketones and 1-azadienes has been developed, and tetrahydropyridines were obtained in good yields and with excellent enantioselectivities. Subsequent exposure of tetrahydropyridines to benzyne leads to a [2 + 2]-cyclization, creating optically enriched polycyclic piperidines with a quaternary stereogenic center and
Phosphine-Catalyzed Enantioselective [4 + 2] Annulation of <i>o</i>-Quinone Methides with Allene Ketones
作者:Zhen Wang、Tianli Wang、Weijun Yao、Yixin Lu
DOI:10.1021/acs.orglett.7b01936
日期:2017.8.4
A phosphine-catalyzed highly enantioselective [4 + 2] annulation between ortho-quinone methides and allene ketones has been developed. The reported method led to the formation of chromane derivatives in high yields and excellent enantioselectivity. This is the first time that ortho-quinone methides are employed in phosphine-mediated cyclization reactions.