Chiral N-phosphino sulfinamide ligands in rhodium(I)-catalyzed [2+2+2] cycloaddition reactions

The combination of cationic rhodium(I) complexes with N-phosphino tert-butylsulfinamides (PNSO) ligands is efficient for catalytic intra- and intermolecular [2+2+2] cycloaddition reactions. PNSO ligands are a new class of chiral bidentate ligands, which have the characteristic of combining the easily accessible sulfur chirality with the coordinating capacity of phosphorous. Cycloaddition of open-chained and macrocyclic E-enediynes with these chiral complexes have proved to be highly efficient in terms of yields, giving moderate enantiomeric excesses of the corresponding cyclohexadiene derivatives. In addition Rh(I)/PNSO complexes catalyzed the intermolecular cycloaddition of diynes with monoalkynes in mild reaction conditions and short reaction times. (C) 2010 Elsevier Ltd. All rights reserved.