Alkene carboamination/oxidative denitrogenation of 3-allyl-3-hydrazinylindolin-2-ones: one-pot entry to spirocyclopropyloxindoles

Org Biomol Chem. 2024 Mar 6;22(10):2124-2136. doi: 10.1039/d3ob02115g.

Abstract

A one-pot protocol, consisting of a Pd-catalysed carboamination reaction, followed by N-deprotection and oxidative denitrogenation, has been developed for the synthesis of diversely substituted spirocyclopropyloxindoles, in yields up to 73% and with diastereoselectivity close to 1 : 1. Readily accessible starting materials, mild reaction conditions, an easy to operate one-pot procedure and good functional group tolerance make this transformation a versatile tool for the synthesis of substituted spirocyclopropyloxindoles. This protocol successfully works on the gram-scale and allows access to both diastereoisomers separately. A plausible mechanism was proposed, and a series of post-transformations were performed on the obtained products, showing their remarkable synthetic versatility.