Rhodium-Catalyzed Asymmetric Dehydrocoupling: Enantioselective Synthesis of a P‑Stereogenic Diphospholane with Mistake-Correcting Diastereoselectivity

• Published in: Organometallics Vol. 42; no. 13; pp. 1448 - 1453
• Main Authors: Chachula, Sarah T., Scheetz, Perry M., Zureick, Andrew H., Hughes, Russell P., Glueck, David S., Hernandez, Ritchie E., Figueroa, Joshua S., Rheingold, Arnold L.
• Format: Journal Article
• Language: English
• Published: American Chemical Society 10-07-2023
• ISSN: 0276-7333; 1520-6041
• DOI: 10.1021/acs.organomet.3c00188

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 C 2-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 C 2-2). 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.