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Metal-Catalyzed Oxa-[4+2] Cyclizations of Quinone Methides with Alkynyl Benzyl Alcohols

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posted on 24.10.2018, 00:00 by Cong-Shuai Wang, Yu-Chun Cheng, Ji Zhou, Guang-Jian Mei, Shu-Liang Wang, Feng Shi
An oxa-[4+2] cyclization of quinone methides with alkynyl benzyl alcohols has been realized in the presence of a metal catalyst, and the reaction afforded spiroacetal products in overall high yields (up to 99%) and good diastereoselectivities (up to >95:5 dr). By carrying out the reaction under gold catalysis and utilizing alkynyl benzyl alcohols as electron-rich reaction partners, this approach provides a useful strategy for settling the challenges in oxa-[4+2] cyclization of para-quinone methide derivatives. This reaction serves as a good example for metal-catalyzed oxa-[4+2] cyclizations of quinone methides. In addition, it also offers a useful method for the construction of spiroacetal skeletons.