Chemoselective carbozincation of cyclopropene for C-C bond formation and cleavage in a single operation

The carbozincation of cyclopropene and cleavage of cyclopropylzinc generates carbanion intermediates, which in turn can generate oligomeric complexes in situ through successive carbozincation reactions. The present reaction controls the carbozincation sequence and C-C bond cleavage to give densely functionalized and sterically congested alkylamines in a single operation. A subtle difference in the substituent at the C=N bond induced chemoselective carbozincation of cyclopropene. The tandem carbozincation of cyclopropene, C-C bond cleavage of the cyclopropylzinc intermediate, and allylation of an unactivated hydrazone proceeds in a single operation. The reaction gives sterically congested amines diastereoselectively.