Synthesis and X-ray characterisation of a new polycondensed heterocycle obtained by a novel Mn(III)-mediated cascade reaction of 2-cyanophenyl isothiocyanate
作者:Gianluca Calestani、Laura Capella、Rino Leardini、Matteo Minozzi、Daniele Nanni、Romina Papa、Giuseppe Zanardi
DOI:10.1016/s0040-4020(01)00678-0
日期:2001.8
loss of a CS moiety. The yields were close to 90% when the reaction was carried out in the presence of diethyl malonate. This compound was unambiguously identified by X-ray crystallography. Under the same conditions, 2-(methoxycarbonyl)phenyl isothiocyanate gave a quinazolinimine derivative instead which is likely to arise from cyclisation of an intermediate N,N′-diarylthiourea. The mechanism of formation
2-氰基苯基异硫氰酸酯与乙酸锰(III)在乙酸或乙腈中反应,可得到新的缩聚杂环化合物,得益于两个起始异硫氰酸酯分子的结合而失去了CS部分,从而得到了新的缩合杂环。当反应在丙二酸二乙酯存在下进行时,收率接近90%。通过X射线晶体学清楚地鉴定出该化合物。在相同条件下,2-(甲氧基羰基)苯基异硫氰酸酯代替了喹唑啉亚胺衍生物,该衍生物可能是由中间体N,N'-二芳基硫脲的环化产生的。前一种化合物的形成机理可能涉及N,N的形成′-双(2-氰基苯基)硫脲,然后进行相应的环状亚胺衍生物的重排和自由基串联闭环。半假设计算也支持该假设。