Formation of Cyclopropanes via Activation of (γ-Methoxy)alkyl Gold(I) Complexes with Lewis Acids

Journal Article (Journal Article)

Treatment of the gold 3-methoxy-3-phenylpropyl complex (P)AuCH2CH2CH(OMe)Ph [P = P(t-Bu)2o-biphenyl] with AlCl3 at -78 °C led to the immediate (≤5 min) formation of a 4:1 mixture of phenylcyclopropane and (1-methoxypropyl)benzene in 86 ± 5% combined yield. Lewis acid activation of the stereochemically pure isotopomer erythro-(P)AuCH2CHDCH(OMe)Ph led to the formation of cis-2-deuterio-1-phenylcyclopropane in 84 ± 5% yield as a single stereoisomer, which established that cyclopropanation occurred with inversion of the γ-stereocenter. Similarly, ionization of the stereochemically pure cyclohexyl gold complex cis-(P)AuCHCH2CH(OMe)CH2CH2CH2 at -78 °C formed bicyclo[3.1.0]hexane in 82% ± 5% yield, which validated a low energy pathway for cyclopropanation involving inversion of the α-stereocenter. Taken together, these observations are consistent with a mechanism for cyclopropane formation involving backside displacement of both the Cγleaving group and the Cα (L)Au+ fragment via a W-shaped transition state.

Full Text

Duke Authors

Cited Authors

  • Kim, N; Widenhoefer, RA

Published Date

  • September 14, 2020

Published In

Volume / Issue

  • 39 / 17

Start / End Page

  • 3160 - 3167

Electronic International Standard Serial Number (EISSN)

  • 1520-6041

International Standard Serial Number (ISSN)

  • 0276-7333

Digital Object Identifier (DOI)

  • 10.1021/acs.organomet.0c00324

Citation Source

  • Scopus