Lactam enables remote boronate rearrangements to C═N bonds

Remote boronate rearrangement of boronic acids to C═N bonds is a valuable in synthetic chemistry. Conventional approaches are constrained by the need to pre-install specialized directing groups onto the starting materials. Here, we report a lactam-driven dynamic directing strategy, achieving 1,5- and 1,4-boronate rearrangements. The strategy circumvents the need for substrate pre-activation procedures, successfully overcoming a challenge in the functionalization of inactive C = N bonds to N-alkyl anilines and 3-aryl quinoxalinones. Comprehensive mechanistic investigations unveil three transformative insights: (i) Lactam leverages boron activation to C = N bonds through tetracoordinate boron species; (ii) the 1,5-boronate rearrangement to N-alkyl anilines is favored via an eight-membered boronate complex, as supported by density functional theory (DFT) studies; (iii) a catalyst-free 1,4-boronate rearrangement pathway operates through HFIP-stabilized tetracoordinate boron intermediates. This lactam-enabled boronate rearrangements offers a methodology with transformative potential. (Figure presented.)