Asymmetric hydroformylations of vinyl sulfides, allyl sulfides, and allyl sulfones catalyzed by (R,S)-BINAPHOS/Rh(acac)(CO)(2) afforded the corresponding branched oxo aldehydes as major products in 60-89% ee. Use of bulkier substituents on the sulfur in vinyl sulfides gave the branched oxo-aldehydes in higher regio- and enantioselectivities.
Phosphonocysteine and Phosphonohomocysteine; Synthesis and Isolation