Acylation of methyl 3-aminocrotonate 1a in benzene with a variety of aliphatic and aromatic acid chlorides including α, β-unsaturated acid chloride in the presence of an added organic base, (either pyridine or triethylamine) is reported. The preferred N, C-site selectivity in these reactions has been compared with the terminal selectivity of the products obtained previously on acylation of methyl 3-aminocrotononitrile 1b. A strong preference either for N- or C- selectivity in N, C-acylation has been observed for both 1a and 1b based on the choice of acid chlorides and added organic base. Interestingly, irrespective of the enamine 1a or 1b, acylation with α, β-unsaturated acid chlorides in the presence of triethylamine afforded 3,4-dihydropyridin-(2H)-one via [3.3] sigmatropic rearrangement of the corresponding intermediary N(E)-enamide. Accrued results show methyl 3-aminocrotonate to be a better precursor for preparation of enamides (N-acylated products) whereas 3-aminocrotononitrile is found to be a preferred choice for preparation of enaminones (C-acylated products). An attempt is made to offer a preliminary theoretical interpretation for observed site selectivity.

中文翻译：

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系统性研究3-氨基巴豆酸甲酯与脂族，芳族和α，β-不饱和酸的酰氯酰化的比较：相对于3-氨基巴豆腈对区域和立体选择性的偏好比较评估

据报道，在添加的有机碱（吡啶或三乙胺）存在下，3-氨基巴豆酸甲酯1a在苯中与各种脂肪族和芳香族酰氯（包括α，β-不饱和酰氯）酰化。已经将这些反应中优选的N，C-位选择性与先前在甲基3-氨基巴豆腈1b的酰化反应中获得的产物的末端选择性进行了比较。基于酰基氯和添加的有机碱的选择，已观察到1a和1b对N或C选择性的强烈选择。有趣的是，与烯胺1a或1b无关在三乙胺的存在下，用α，β-不饱和酰氯酰化，通过相应的中间N（E）-酰胺的[3.3]σ重排，得到3,4-二氢吡啶-（2 H）-一。应计的结果表明，3-氨基巴豆酸甲酯是制备烯酰胺（N-酰化产物）的较好前体，而3-氨基巴豆腈被发现是制备烯胺酮（C-酰化产物）的优选选择。试图为观察到的位点选择性提供初步的理论解释。