Display options
Cite
Cho BR, Jeong HC, Seung YJ, et al. Ketene-forming eliminations from aryl phenylacetates promoted by R2NH/R2NH2+ in aqueous MeCN. Mechanistic borderline between E2 and E1cb. J Org Chem. 2002;67(15):5232-8doi: 10.1021/jo025555m.
Cho, B. R., Jeong, H. C., Seung, Y. J., & Pyun, S. Y. (2002). Ketene-forming eliminations from aryl phenylacetates promoted by R2NH/R2NH2+ in aqueous MeCN. Mechanistic borderline between E2 and E1cb. The Journal of organic chemistry, 67(15), 5232-8. https://doi.org/10.1021/jo025555m
Cho, Bong Rae, et al. "Ketene-forming eliminations from aryl phenylacetates promoted by R2NH/R2NH2+ in aqueous MeCN. Mechanistic borderline between E2 and E1cb." The Journal of organic chemistry vol. 67,15 (2002): 5232-8. doi: https://doi.org/10.1021/jo025555m
Cho BR, Jeong HC, Seung YJ, Pyun SY. Ketene-forming eliminations from aryl phenylacetates promoted by R2NH/R2NH2+ in aqueous MeCN. Mechanistic borderline between E2 and E1cb. J Org Chem. 2002 Jul 26;67(15):5232-8. doi: 10.1021/jo025555m. PMID: 12126411.
Copy Download .nbib Format: NLM
Share it on

J Org Chem. 2002 Jul 26;67(15):5232-8. doi: 10.1021/jo025555m.

Ketene-forming eliminations from aryl phenylacetates promoted by R2NH/R2NH2+ in aqueous MeCN. Mechanistic borderline between E2 and E1cb.

The Journal of organic chemistry

Bong Rae Cho, Hyun Cheol Jeong, Yoon Je Seung, Sang Yong Pyun

Affiliations

  1. Department of Chemistry, Korea University, 1-Anamdong, Seoul, 136-701, Korea. [email protected]

PMID: 12126411 DOI: 10.1021/jo025555m

Abstract

Elimination reactions of 2-X-4-NO2C6H3CH2C(O)OC6H3-2-Y-4-NO2 [X = H (1), NO2 (2)] promoted by R2NH/R2NH2+ in 70 mol % MeCN(aq) have been studied kinetically. The base-promoted eliminations from 1 proceeded by the E2 mechanism when Y = Cl, CF3, and NO2. The mechanism changed to the competing E2 and E1cb mechanisms by the poorer leaving groups (Y = H, OMe) and to the E1cb extreme by the strongly electron-withdrawing beta-aryl group (2, X = NO2). The values of beta = 0.14 and beta(lg) = 0.10-0.21 calculated for elimination from 1 (Y = NO2) indicate a reactant-like transition state with small extents of proton transfer and C(alpha)-OAr bond cleavage. The extent of proton transfer increased with a poorer leaving group, and the degree of leaving group bond cleavage increased with a weaker base. Also, the changes in the k(1) and k(-1)/k(2) values with the reactant structure variation are consistent with the E1cb mechanism. From these results, a plausible pathway of the change of the mechanism from E2 to the E1cb extreme is proposed.

Publication Types