Z-Selective Hydrothiolation of Racemic 1,3-Disubstituted Allenes: An Atom-Economic Rhodium-Catalyzed Dynamic Kinetic Resolution.

A Z-selective rhodium-catalyzed hydrothiolation of 1,3-disubstituted allenes and subsequent oxidation towards the corresponding allylic sulfones is described. Using the bidentate 1,4-bis(diphenylphosphino)butane (dppb) ligand, Z/E-selectivities up to >99:1 were obtained. The highly atom-economic desymmetrization reaction tolerates functionalized aromatic and aliphatic thiols.

Asymmetric rhodium-catalyzed addition of thiols to allenes: synthesis of branched allylic thioethers and sulfones.

A highly regio- and enantioselective hydrothiolation of terminal allenes, a reaction which fulfills the criteria of atom economy, is reported. Applying two chiral rhodium catalyst systems, a wide variety of thiols and allenes could be coupled. Oxidation gave access to the corresponding allylic sulfones in essentially enantiomerically pure form.