Dirhodium Carboxylate Catalysts from 2‐Fenchyloxy or 2‐Menthyloxy Arylacetic Acids: Enantioselective C−H Insertion, Aromatic Addition and Oxonium Ylide Formation/Rearrangement

A new class of dirhodium carboxylate catalysts have been designed and synthesized from 2‐fenchyloxy or 2‐menthyloxy arylacetic acids which display excellent enantioselectivity across a range of transformations of α‐diazocarbonyl compounds. The catalysts were successfully applied to enantioselective C−H insertion reactions of aryldiazoacetates and α‐diazo‐β‐oxosulfones affording the respective products in up to 93 % ee with excellent trans diastereoselectivity in most cases. Furthermore, efficient desymmetrization in an intramolecular C−H insertion was achieved. In addition, these catalysts prove highly enantioselective for intramolecular aromatic addition with up to 88 % ee, and oxonium ylide formation and rearrangement with up to 74 % ee.