Diastereoselective [4+1] Cycloaddition of Alkenyl Propargylic Tertiary Acetates with CO Catalyzed by [RhCl(CO)₂]₂

Abstract

Alkenyl propargylic tertiary acetates were prepared by deprotonation of the corresponding enyne followed by nucleophilic addition to ketones and then treatment with acetic anhydride. The resulting acetates were then employed in diastereoselective [4+1] cycloadditions with CO catalyzed by [RhCl(CO)2]2 to form α‐benzylidene cyclopentenone derivatives. We found the cycloadditions of the tertiary acetates to be more diastereoselective than those of the corresponding secondary acetates, as a result of increased substitution at the propargylic carbon. When an electron‐donating meta substituent, such as Me and MeO, is introduced to the aryl group at the propargylic carbon of the tertiary acetate, the diastereoselectivity improved to >8:1 (E/Z).

Progress in Transition-Metal-Catalyzed Carbonylative Cycloadditions Using Carbon Monoxide

“…题组 [116] 使用乙酰基取代的化合物 5.41 完成了类似的铑 催化的[4＋1]反应(Scheme 23b). 之后, 余孝其、蒲林和 赵刚等 [117][118] 使用酰氧基处于端侧的烯炔 5.43 和 CO, 发展了一类新的包含 1,3-酰氧基迁移的铑催化的[4＋1] 反应(Scheme 23c). 对于反应过程, 他们认为: 在铑催化 下, 酰氧基迁移所产生的乙烯基联烯同 CO 发生[4＋1] 环加成反应.…”