87. Chachula, S. T.; Scheetz, P. M.; Zureick, A. H.; Hughes, R. P.; Glueck, D. S.; Hernandez, R. E.; Figueroa, J. S.; Rheingold, A. L. Rhodium-Catalyzed Asymmetric Dehydrocoupling: Enantioselective Synthesis of a P-Stereogenic Diphospholane with Mistake-Correcting Diastereoselectivity. Organometallics 2023, 42, 1448–1453.  

http://dx.doi.org/10.1021/acs.organomet.3c00188

  

Abstract

Catalytic asymmetric dehydrocoupling of secondary phosphines is a potentially valuable route to enantiomerically enriched P-stereogenic diphosphines for use as ligands or building blocks for chiral bis(phosphines). Rh(diphos*) catalyst precursors converted a rac/meso mixture of PhHP(CH₂)₃PHPh (1) to the C₂-symmetric P-stereogenic anti-diphospholane PhP(CH₂)₃PPh (2) in up to a 58:42 enantiomeric ratio (er) with complete diastereoselectivity via catalyst-mediated isomerization of the intermediate syn-diphospholane 3 to 2 (mistake correction by conversion of the diastereomer meso-3 to chiral C₂-2). NMR studies of catalytic reactions identified the resting state Rh((R,R)-i-Pr-DuPhos)(PhHP(CH₂)₃PPh) (4) and suggested a proposed mechanism for stereocontrolled P–P bond formation via oxidative addition and reductive elimination steps.