A one-carbon homologation of Knoevenagel adducts enabling the insertion of a CHAr fragment is reported. The strategy involves a sulfur ylide mediated cyclopropanation followed by the rearrangement of cyclopropanes and enables the synthesis of a series of benzhydryl derivatives. Mechanistic studies reveal that the cyclopropane rearrangement involves a Lewis acid catalyzed ring-opening followed by the 1,2-migration of an aryl group. The possibility of controlling the absolute stereochemistry of the generated stereogenic allylic carbon center using a chiral sulfonium ylide is demonstrated.

中文翻译：

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Knoevenagel 加合物的一碳同系化：对映选择性获得二苯甲基衍生物

据报道，Knoevenagel 加合物的一碳同系物能够插入 CHAr 片段。该策略涉及硫叶立德介导的环丙烷化，然后进行环丙烷的重排，并能够合成一系列二苯甲基衍生物。机理研究表明，环丙烷重排涉及路易斯酸催化的开环，随后是芳基的 1,2-迁移。证明了使用手性锍叶立德控制生成的立体烯丙基碳中心的绝对立体化学的可能性。