Tetrahedron p. 459 - 463 (2019)
Update date:2022-08-02
Timofeeva, Daria S.
Ofial, Armin R.
Mayr, Herbert
Treatment of α-imino esters derived from glycine esters and benzophenone or benzaldehydes with potassium tert butoxide in DMSO gave persistent solutions of carbanions at 20 °C. The kinetics of their reactions with quinone methides and benzylidene malonates (reference electrophiles) have been followed photometrically under pseudo-first order conditions. The reactions followed second-order rate laws. Since addition of 18-crown-6 ether did not affect the reaction rates, the measured rate constants correspond to the reactions of the non-paired carbanions. Plots of the second-order rate constants against the electrophilicity parameters E of the electrophiles are linear, which allowed us to derive the nucleophile-specific parameters N and sN, according to the linear Gibbs energy relationship lg k2(20 °C) = sN(N + E). The Ph2C = N- and PhCH = N- groups act as very weak electron acceptors with the consequence that Ph2C = N-CH–-CO2R and PhCH = N-CH–-CO2R have a similar nucleophilicity as Ph-CH–-CO2Et, the anion of ethyl phenylacetate.
View MoreContact:18698110882
Address:1303 No2 building,LuoMa Garden,YongAn Road,Hexi District,Tianjin city
website:https://www.sinoshiny.com/products
Contact:+86-20-62802632;62802633
Address:Room 330 GIGCAS Building,No.511 Kehua Street,Tianhe District
Zhengzhou Institute of Chiral Pharmer Research Co., Ltd.
Contact:86-371-55219111
Address:15 Floor, 2 Building, Central China Technovalley, Zhongyuan West Road
Contact:18669908765
Address:Zibo City, Shandong Province, P.R.China
Shandong Dayi Chemical Co., Ltd.
website:http://www.dayi.com.cn
Contact:+86- 535-7388728. 15306386031
Address:No 1 Danya west road, Laiyang City, Shandong province
Doi:10.1002/jhet.3705
(2019)Doi:10.1016/S0040-4020(01)99119-7
(1966)Doi:10.1016/S0040-4020(01)91029-4
(1991)Doi:10.1016/S0040-4020(01)87231-8
(1993)Doi:10.1016/S0040-4020(01)96219-2
(1991)Doi:10.1002/jhet.819
(2012)