Catalytic Asymmetric Syntheses of Alkylidenecyclopropanes from Allenoates with Donor‐Acceptor and Diacceptor Diazo Reagents

The first diastereo‐ and enantioselective cyclopropanation reactions of electron‐deficient allenes with donor‐acceptor and diacceptor diazo reagents are described. The desired enantioenriched alkylidenecyclopropanes (ACPs) were obtained in high yields with high diastereo‐ and enantioselectivities in the presence of Rh2((S)‐TCPTAD)4 or Rh2((R)‐BTPCP)4 catalysts (up to 95 % yield, >95 : 5 d.r. and 99 : 1 e.r.). This methodology gave a direct access to ACPs bearing multiple electron‐deficient substituents and allows to further expand the availability of ACPs chemistry. Interestingly, during the examination of the scope of this reaction, the asymmetric intramolecular C−H insertion reaction into tert‐butyl group was observed as a side reaction with up to 94 : 6 e.r.