Biaryl-substituted unsymmetrical diarsanes: transformation into As-stereogenic Buchwald-type ligands.

Unsymmetrical biaryl-substituted diarsanes were synthesized from dithiaarsoles under Grignard conditions. The reaction selectively afforded sterically congested frameworks that were previously difficult to access. Structural and computational studies revealed relatively low arsenic inversion barriers, enabling thermal meso-rac interconversion. Controlled oxidative As-As bond cleavage furnished As-stereogenic arsa-Buchwald ligands.