Reagent- and Ligand-Dependent Mechanistic Trichotomy in Fe-Catalyzed Borylative Cyclizations of Enynes

Org Lett. 2024 Aug 2;26(30):6370-6374. doi: 10.1021/acs.orglett.4c02088. Epub 2024 Jul 25.

Abstract

Based on some very recent results on Fe-catalyzed boron-source-dependent regiodivergent hydroborations of internal alkynes, we report here a boron-source-dependent but also ligand-dependent mechanistic trichotomy in borylative cyclizations. The choice of ligand plus boron source allows the synthesis of three isomeric borylative cyclization products starting from a common substrate and using the same precatalyst ((Ph3P)2Fe(CO)(NO)H) and sets the stage for the development of a unifying concept in Fe-catalyzed borylative cyclizations.