Push–pull alkenes from cyclic ketene-N,N′-acetals: a wide span of double bond lengths and twist angles
作者:Guozhong Ye、Sabornie Chatterjee、Min Li、Aihua Zhou、Yingquan Song、Bobby Lloyd Barker、Chunlong Chen、Debbie J. Beard、William P. Henry、Charles U. Pittman
DOI:10.1016/j.tet.2010.02.071
日期:2010.4
the reactions of (1) N,N′-dimethyl cyclic ketene-N,N′-acetals with isocyanates, (2) the products from (1) with isocyanates, (3) 2-methylimidazoline and 2-methyl-1,4,5,6-tetrahydropyrimidine with diacid chlorides, (4) 2-methylimidazoline, and 1,2-dimethyl-1,4,5,6-tetrahydropyrimidine with benzoyl chlorides, and (5) 1,2-dimethylimidazoline and 1,2-dimethyl-1,4,5,6-tetrahydropyrimidine with aryl isocyanates
推挽式烯烃可以通过环烯酮-N,N'-缩醛化学快速获得。从(1)N,N'-二甲基环状烯酮-N,N'-乙缩醛与异氰酸酯的反应中合成了许多具有双键长度和扭曲角跨度的推挽结构,(2)产物从(1)与异氰酸酯,(3)2-甲基咪唑啉和2-甲基-1,4,5,6-四氢嘧啶和二酰氯,(4)2-甲基咪唑啉和1,2-二甲基-1,4,5,6-四氢嘧啶与苯甲酰氯,和(5)1,2-二甲基咪唑啉和1,2-二甲基-1,4,5,6-四氢嘧啶与芳基异氰酸酯。这些反应在非常温和的条件下进行,并且产率中等至优异。八个pxush-pull烯烃的X射线晶体学分析表明,中心双键长度和扭曲对环尺寸(5或6),环结构(稠合或非稠合),电子给体和抽出和推压强度敏感。拉部分分别是电子推或拉基的数目和取代基的空间效应。