Anti-Selective [3+2] (Hetero)annulation of Non-Conjugated Alkenes via Directed Nucleopalladation
2020-06-22T11:42:26Z (GMT) by
2,3-Dihydrobenzofurans and indolines are common substructures in medicines and natural products. Herein, we describe a method that enables direct access to these core structures from non-conjugated alkenyl amides and ortho-iodoanilines/phenols. Under palladium(II) catalysis this [3+2] heteroannulation proceeds in an anti-selective fashion and tolerates a wide variety of functional groups. N-Acetyl, -tosyl, and -alkyl substituted ortho-iodoanilines, as well as free –NH2 variants, are all effective. Preliminary results with carbon-based coupling partners also demonstrate the viability of forming indane core structures using this approach. Experimental and computational data with phenols support a mechanism involving turnover-limiting, endergonic directed oxypalladation, followed by intramolecular oxidative addition and reductive elimination.