Journal of Organic Chemistry p. 7244 - 7250 (1991)
Update date:2022-08-05
Topics:
Adam, Waldemar
Wang, Xiaoheng
In the presence of catalytic amounts of CF3COCH3 or CF3COCF3, the silyl ketene acetal E-1 was isomerized into its Z isomer (Z/E ratio 90:10).For this novel E/Z isomerization a mechanism is proposed, in which addition and reelimination of the fluoro ketone, through a 1,4-dipolar intermediate operates.With the protic nucleophiles CH3OH, CF3CH2OH, or PhOH, the ketene acetal E-1 afforded the ortho esters 2 as addition products, while CH3CO2H, CF3CO2H, or H2O led to methyl pivalate as the solvolysis product.This chemistry is readily explained through protonation of the ketene acetal E-1 to generate the corresponding carbenium ion.At low temperature the reaction with TCNE gave the silylketene imine 3 as labile cycloadduct, which underwent on workup desilylation to give the TCNE-incorporated ester 6; the latter eliminated hydrogen cyanide at room temperature to give the ene ester 7.With MTAD the labile silyl ene product 4 was obtained initially, which underwent silyl migration to give N-silylated urazole 8; final desilylation led to the stable urazole 9.Also for the ene reactions of TCNE and MTAD with the silyl ketene acetal E-1, a 1,4-dipolar intermediate is proposed to intervene.
View MoreXian Changyue Biological Technology Co., Ltd.
website:https://www.xachangyue.com/
Contact:+86-029-62886900
Address:Keji Road NO.70
Shandong Jincheng Zhonghua Bio-pharmaceutical Co.,Ltd
Contact:+86-533-5415882
Address:Zichuan Economic Development Zone,Zibo City,Shandong Province,China
Jiaozuo Zhongwen Trading Coporation Limited
Contact:+86 0391-3553810
Address:East Renmin Road
Chengdu Sino-Strong Pharmaceutical Co.,Ltd.
website:http://www.sino-strong.com.cn
Contact:+86-28-82666753
Address:459 West haike road,Cross-straits technological industry park, Wenjiang district,Chengdu, P.R.China
Wuhan Sun-shine Bio-technology Corporation Limited
Contact:+862765522452
Address:武汉市东湖高新区高新二路388号生物医药加速器16栋501
Doi:10.1021/ja00027a023
(1992)Doi:10.1002/asia.201100805
(2012)Doi:10.1039/c3ra43110j
(2013)Doi:10.1016/j.tet.2012.02.081
(2012)Doi:10.1080/10426507.2011.634467
(2012)Doi:10.1021/ja01250a012
(1943)