Enantioselective Synthesis of C2-Quaternary Indolin-3-ones by Pt-Catalyzed Alkynylation of 2-Aryl-3H-indol-3-one with Alkynylsilanes

An efficient method for the synthesis of five-membered chiral propargylic amines from 2-aryl-3H-indol-3-one and alkynylsilanes has been developed. The reaction proceeded under the catalytic system of PtCl4, oxazoline-based ligand L11, Zn(CF3COO)2, and AcOH in DCE at 95 °C via in situ desilylation of TMS-alkynes. This methodology also highlights a new protocol for the in situ desilylation of alkynylsilanes. The reaction showed a broad substrate scope with good yields and enantioselectivity.