以2-氨基-4-三氟甲基-5-甲基-噻吩-3-羧酸乙酯(1)为起始原料制得膦亚胺2. 在碳酸钾的催化下, 膦亚胺2 与芳基异氰酸酯和伯二胺的氮杂Wittig 反应制得嘧啶环上2,2'取代的双[噻吩并[2,3-d]嘧啶-4(3H)-酮] 3; 膦亚胺2 与烷基异氰酸酯和伯二胺的氮杂Wittig 反应制得嘧啶环上3,3'取代的双[噻吩并[2,3-d]嘧啶-4(3H)-酮] 4. 化合物3 的核磁共振氢谱表明关环反应在嘧啶环的2,2'位; 化合物4 的核磁共振氢谱表明关环反应在嘧啶环的3,3'位. 对合成反应机理的推导及目标产物核磁共振氢谱数据的分析解释了此合成反应的选择性.
The iminophosphorane 2 was obtained using ethyl 2-amino-4-trifluoromethyl-5-methyl-thiophene-3-carboxylate (1) as starting materials. Further aza-Wittig reactions of iminophosphorane 2 with aromatic isocyanate and primary diamine produced 2,2'-disubstituted bis(thieno[2,3-d]pyrimidin-4(3H)-ones) 3 in the presence of catalytic amounts of potassium carbonate in 70%～87% yields. Aza-Wittig reactions of iminophosphorane 2 with alkyl isocyanate and primary diamine produced 3,3'-disubstituted bis(thieno[2,3-d]pyrimidin-4(3H)-ones) 4 in 38%～57% yields. 1H NMR of compound 3 revealed the exclusive selectivity of these ring closures toward the 2,2'-disubstituted position of pyrimidine moiety, and 1H NMR of compound 4 revealed the exclusive selectivity of these ring closures toward the 3,3'-disubstituted position of pyrimidine moiety. The reaction mechanism was also proposed for the regioselectivity.
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