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Published October 3, 2007 | Supplemental Material
Journal Article Open

The Inner-Sphere Process in the Enantioselective Tsuji Allylation Reaction with (S)-t-Bu-phosphinooxazoline Ligands

Abstract

We propose an inner-sphere mechanism explaining the unique performance of the Tsuji asymmetrical allylation reaction using hard prochiral enolate nucleophiles and non-prochiral allyl groups. Using first principles quantum mechanics (B3LYP density functional theory), we find that the pathway for this reaction involves nucleophilic attack followed by interconversion from a five-coordinate Pd complex to a four-coordinate complex. This intermediate is trapped in a potential well and escapes via reductive elimination that proceeds through a seven-membered transition state to generate the product and a Pd^0 complex. This seven-membered transition state contrasts dramatically from the usual three-centered C−C reductive elimination paradigm generally associated with C−C coupling reactions. This inner-sphere asymmetric allylation pathway involving hard enolates is energetically more favorable than outer-sphere nucleophilic attack, a process understood to occur in asymmetric allylic alkylations with soft enolates.

Additional Information

© 2007 American Chemical Society. Received 26 January 2007. Published online 8 September 2007. Published in print 1 October 2007. We thank K. Tani, A. Harned, J. Enquist, and N. Sherden for experimental collaboration and discussion, and M. Day and L. Henling for crystallography assistance. J.A.K. thanks R. (Smith) Nielsen for discussions. This research was partly funded by Chevron-Texaco, and the facilities used were funded by grants from ARO-DURIP, ONR-DURIP, IBM-SUR, Fannie and John Hertz Foundation (D.C.B.), and Eli Lilly (J.T.M.) with additional support from NSF (CTS-0608889, WAG) and NIH-NIGMS (R01GM080269-01, BMS).

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August 19, 2023
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