Arsenous chloride-free synthesis of cyclic tertiary organoarsines from arylarsine oxides and di-Grignard reagents

The growing importance of triarylarsines as ligands for transition metal catalysis has sparked recent interest in new synthetic routes to tertiary arsines that avoid hazardous arsenous chloride reagents. However, safer methods for the synthesis of lesser explored arsine heterocycles, especially those containing As-C(sp3) bonds, remain lacking. We demonstrate for the first time that bench stable, less hazardous, arylarsine(III) oxides are effective substitutes for their corresponding chlorides in the one-pot construction of cyclic tertiary organoarsines from di-Grignard reagents. Several known and novel heterocycles have been prepared in reasonable yields, accommodating variations in both the diorganomagnesium reagent and electrophile, making this a modular approach to cyclic arsine assembly.