Microwave-induced generation and reactions of nitrile sulfides: an improved method for the synthesis of isothiazoles and 1,2,4-thiadiazoles
作者:Euan A.F. Fordyce、Angus J. Morrison、Robert D. Sharp、R. Michael Paton
DOI:10.1016/j.tet.2010.06.068
日期:2010.8
The 1,3-dipolar cycloaddition reactions of nitrile sulfides, generated by microwave-assisted decarboxylation of 1,3,4-oxathiazol-2-ones, have been investigated. By this approach ethyl 1,2,4-thiadiazole-5-carboxylates 3 were prepared in good yield by cycloaddition of the nitrile sulfides to ethyl cyanoformate. Similarly, reaction of benzonitrile sulfide with dimethyl acetylenedicarboxylate (DMAD) afforded
已经研究了微波辅助1,3,4-氧杂噻唑-2-酮的脱羧反应生成的腈类硫化物的1,3-偶极环加成反应。通过这种方法,通过将腈硫化物环加成氰基甲酸乙酯,以高收率制备了1,2,4-噻二唑-5-羧酸乙酯3。类似地,使苄腈硫化物与乙炔二羧酸二甲酯(DMAD)反应,得到3-苯基异噻唑-4,5-二羧酸二甲酯(5)。与此相反,直径: -hydroxybenzonitrile硫化物,从相应的oxathiazolone生成2D,与DMAD反应,得到4-氧代-4- ħ - [1]苯并吡喃并[4,3- c ^ ]异噻唑-3-羧酸乙酯(8)高产。大约 1:3-苯基异噻唑4-和5-羧酸酯(1混合物6,7)从苄腈硫化物和丙炔酸乙酯形成。与富马酸二乙酯的相应反应得到反式-4,5-二氢-3-苯基异噻唑-4,5-二硬脂酸二乙酯(10)。3-芳基噻唑在4位和5位上均未取代,是由5-芳基-1,3,4-氧杂噻唑酮与降冰片二烯通过涉及