Catalytic Enantioselective Synthesis of Functionalized Cyclopropanes from α-Substituted Allyl Sulfones with Donor-Acceptor or Diacceptor Diazo Reagents.

The catalytic asymmetric synthesis of highly functionalized cyclopropanes from α-substituted allyl sulfones and silanes is reported. The reaction, using α-aryl diazoacetates or diacceptor diazo reagents, catalyzed by a chiral rhodium complex (Rh 2 ((S)-BTPCP) 4 ), furnished the corresponding cyclopropanes in moderate to high yields (27-97 %), high diastereoselectivities (68 : 32 to 20 : 1 d.r.) and moderate to excellent ee (40-99 %). This methodology offers a privileged access to an underexplored class of enantioenriched cyclopropanes with a high level of functionality, an asset for further post-functionalization and their incorporation into more complex structure.