Palladium-catalyzed asymmetric phosphination. Enantioselective synthesis of PAMP-BH3, ligand effects on catalysis, and direct observation of the stereochemistry of transmetalation and reductive elimination

Julian R. Moncarz, Tim J. Brunker, John C. Jewett, Michael Orchowski, David S. Glueck, Roger D. Sommer, Kin Chung Lam, Christopher D. Incarvito, Thomas E. Concolino, Christopher Ceccarelli, Lev N. Zakharov, Arnold L. Rheingold

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65 Scopus citations

Abstract

The complexes Pd(diphos)(o-An)(I) (o-An = o-MeOC6H4; diphos = dppe (3), (S,S)-Chiraphos (4), (R,R)-Me-Duphos (5), (R,S) -t-Bu-Josiphos (6), (R)-Tol-Binap (7)) were prepared. Complex 6 catalyzed the coupling of PH(Me)(Ph)(BH3) (2) with o-AnI in the presence of base to yield PAMP-BH3 (P(Me)(Ph)(o-An)(BH3) (1)) in low enantiomeric excess. The course of stoichiometric reactions of 3-7 with 2 and NaOSiMe3 depended on the diphosphine ligand. Complexes 6 and 7 gave PAMP-BH3 (1) and Pd(0) species; no intermediates were observed. With 3, the intermediate Pd(dppe)(o-An)(P(Me)(Ph)(BH3)) (10) was observed by 31P NMR, while 4 gave the isolable diastereomeric palladium complexes (Sp)-Pd((S,S)-Chiraphos)(o-An)(P(Me)(Ph)(BH3)) (11a) and (RP)-Pd((S,S)-Chiraphos)(o-An)(P(Me)(Ph)(BH3)) (11b), whose absolute configurations were determined by X-ray crystallography after separation. The analogous Pd((R,R)-Me-Duphos)(o-An)(P(Me)(Ph)(BH3)) diastereomers (12a,b) were also separated and isolated. Treatment of 4 with highly enantioenriched 2 (R or S) gave 11a or 11b in high diastereomeric excess with retention of configuration at phosphorus. P-C reductive elimination from either isomer of highly diastereoenriched 11 in the presence of excess diphenylacetylene yielded Pd((S,S)-Chiraphos)(PhC≡CPh) (14) and highly enantioenriched PAMP-BH3 (1), with retention of configuration.

Original languageEnglish (US)
Pages (from-to)3205-3221
Number of pages17
JournalOrganometallics
Volume22
Issue number16
DOIs
StatePublished - Aug 4 2003
Externally publishedYes

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Organic Chemistry
  • Inorganic Chemistry

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    Moncarz, J. R., Brunker, T. J., Jewett, J. C., Orchowski, M., Glueck, D. S., Sommer, R. D., Lam, K. C., Incarvito, C. D., Concolino, T. E., Ceccarelli, C., Zakharov, L. N., & Rheingold, A. L. (2003). Palladium-catalyzed asymmetric phosphination. Enantioselective synthesis of PAMP-BH3, ligand effects on catalysis, and direct observation of the stereochemistry of transmetalation and reductive elimination. Organometallics, 22(16), 3205-3221. https://doi.org/10.1021/om030144x