Rhodium-Catalyzed Regiodivergent Hydrothiolation of Allyl Amines and Imines

• DOI: 10.1021/jacs.6b07142
• Publication Date: 2016-08-22T21:37:20Z
• Authors: Jennifer L. Kennemur; Gregory D. Kortman; Kami L. Hull
• Keywords: 01 natural sciences; 0104 chemical sciences

The regiodivergent Rh-catalyzed hydrothiolation of allyl amines and imines is presented. Bidentate phosphine ligands with larger natural bite angles (βn ≥ 99°), for example, DPEphos, dpph, or L1, promote a Markovnikov-selective hydrothiolation in up to 88% yield and >20:1 regioselectivity. Conversely, when smaller bite angle ligands (βn ≤ 86°), for example, dppbz or dppp, are employed, the anti-Markovnikov product is formed in up to 74% yield and >20:1 regioselectivity. Initial mechanistic investigations are performed and are consistent with an oxidative addition/olefin insertion/reductive elimination mechanism for each regioisomeric pathway. We hypothesize that the change in regioselectivity is an effect of diverging coordination spheres to favor either Rh-S or Rh-H insertion to form the branched or linear isomer, respectively.