Asymmetric synthesis of SMS-Phos series' precursor and a naphthalene analogue

An efficient and high-yielding (up to 57% overall yield) asymmetric route to enantiopure P-stereogenic 1,2-bis[(o-hydroxyaryl)(phenyl)phosphino-P-borane]ethanes wherein aryl = phenyl and naphthyl, is presented. The occurring P-stereomutation is confirmed through X-ray crystal structure analysis of key intermediates.