Development of New C-N and C-P Bond Formations with Alkenes and Alkynes Based on Electrophilic Amination and Phosphination

Abstract

Nitrogen and phosphorus are ubiquitously found in biologically active compounds, natural products, pharmaceutical agents, synthetic reagents, and even organic functional materials. The introduction of these heteroatoms into organic skeletons by the development of C-N and C-P bond forming reactions has been one of the long-standing research goals of synthetic chemistry. Both nitrogen and phosphorus have one lone pair, and synthetic chemists have therefore developed many nucleophilic amination and phosphination reactions. On the other hand, our research group has recently been focusing on the unique reactivity of hydroxylamines and hydroxylphosphines (tautomers of secondary phosphine oxides), and has developed otherwise challenging C-N and C-P bond-forming reactions with alkenes and alkynes based on electrophilic amination and phosphination using these reagents. In this account, we present an umpolung-enabled, copper-catalyzed, regio- and stereoselective aminoboration and hydroamination of alkenes, including unactivated terminal alkenes as well as electronically and sterically activated styrenes, strained alkenes, and vinylboranes/silanes. Additionally, a similar umpolung, electrophilic phosphination of alkynes under Tf₂O-promoted, metal-free conditions is also described.