Palladium-catalyzed intramolecular enantioselective C(sp)-H insertion of donor/donor carbenes.

Herein, the first palladium-catalyzed intramolecular enantioselective C(sp)-H insertion reaction of donor-donor carbenes has been successfully achieved. This facile protocol enables the rapid construction of a collection of enantioenriched decorated indolines with two contiguous stereocenters in a single step. Both enynones and diazo compounds are efficient donor-donor carbene precursors for this reaction. By an adjustment of ligands and protecting groups of the substrates, the palladium-carbene intermediates from diazo compounds afford sparse -indolines with excellent enantioselectivities, while carbenes from enynones deliver -indolines exclusively. Based on the control reactions and Hammett analysis, a stepwise Mannich-type pathway through a short-lived and compact zwitterionic intermediate is proposed.