1,3-cycloadditions of aliphatic thione S-methylides to dimethyl 2,3-dicyanofumarate and 2,3-dicyanomaleate; a test case for steric course and mechanism
作者:Grzegorz Mloston、Elke Langhals、Rolf Huisgen
DOI:10.1016/s0040-4039(01)93790-6
日期:1989.1
The 1,3-cycloadditions of thione S-methylides and to dimethyl 2,3-dicyanofumarate and 2,3-dicyanomaleate are nonstereospecific. A preceding cis,trans isomerization of the unsaturated dipolarophiles catalyzed by the thiadiazolines (precursors of the thione S-methylides) had to be suppressed in order to clarify the stereochemical leakage during the cycloaddition.
的1,3-环加成硫酮小号-methylides和对二甲基2,3- dicyanofumarate和2,3- dicyanomaleate是nonstereospecific。为了阐明在环加成过程中的立体化学泄漏,必须抑制由噻二唑啉(硫酮S-甲基化物的前体)催化的不饱和双极性亲和剂的先前的顺式,反式异构化。