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A mechanistic investigation into the zinc carbenoid-mediated homologation reaction by DFT methods: is a classical donor-acceptor cyclopropane intermediate involved?

ABSTRACT: An extensive density functional theory (DFT, M05-2X) investigation has been performed on the zinc carbenoid-mediated homologation reaction of ?-keto esters. The mechanistic existence of a classical donor-acceptor cyclopropane intermediate was probed to test the traditional school of thought regarding these systems. Calculations of the carbenoid insertion step, following enolate formation, unmasked two possible pathways. Pathway B was shown to explain the proposed, but spectroscopically unobservable donor-acceptor cyclopropane intermediate, while the second (pathway A) reveals an alternative to the classical intermediate in that a cyclopropane transition state leads to product.

SUBMITTER: Eger WA

PROVIDER: S-EPMC3237639 | biostudies-literature | 2010 Nov

REPOSITORIES: biostudies-literature

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A mechanistic investigation into the zinc carbenoid-mediated homologation reaction by DFT methods: is a classical donor-acceptor cyclopropane intermediate involved?

Eger Wilhelm A WA Zercher Charles K CK Williams Craig M CM

The Journal of organic chemistry 20101101 21

An extensive density functional theory (DFT, M05-2X) investigation has been performed on the zinc carbenoid-mediated homologation reaction of β-keto esters. The mechanistic existence of a classical donor-acceptor cyclopropane intermediate was probed to test the traditional school of thought regarding these systems. Calculations of the carbenoid insertion step, following enolate formation, unmasked two possible pathways. Pathway B was shown to explain the proposed, but spectroscopically unobserva ...[more]

PMID: 20879758

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