Masked: Donor–acceptor cyclopropanes undergo a cycloaddition reaction with ketenedithioacetals under Lewis acid catalysis. Cleavage of the dithiane unit leads to cyclopentanones. As a result of this two‐step process, formally an acceptor‐substituted ketene is inserted into the three‐membered ring system.

中文翻译：

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酮基二乙缩醛作为替代形式，将酮基形式正式插入供体-受体环丙烷中

掩蔽的：供体-受体环丙烷在路易斯酸催化下与酮二硫缩醛发生环加成反应。二噻吩单元的裂解导致环戊烷。通过此两步过程，可以将受体取代的烯酮正式插入三元环系统中。