Asymmetric synthesis of isochromanone derivatives via trapping carboxylic oxonium ylides and aldol cascade

A highly enantioselective cascade Z -selective-1,3-OH insertion/aldol cyclization of ketoacids with diazoketones involving carboxylic oxonium ylides was achieved by using a bimetallic Rh( ii )/chiral N , N ′-dioxide-Fe( iii ) or Sc( iii ) complex catalyst.