3-羟基异噁唑的O-和N-酰化及其区域选择性研究 Ⅱ.3-羟基-5-甲基异噁唑O-和N-酰化产物的选择性合成

Studies on O-and N-Acylation of 3-Hydroxyisoxazole and Their Regioselectivity Ⅱ. Regioselective Synthesis of O-/N-Acylation Products of 5-Methyl-3-Hydroxyisoxazole

本文研究了不同反应条件下3-羟基-5-甲基异噁唑(1)与3-甲基-2-对氯苯基丁酰氯(2a)的反应,提出了区域选择性合成O-和N-酰化产物的方法。在三乙胺存在下,乙腈为溶剂,1和2a～2e反应得到含量为88～96％的O-酰化产物3a～3e;而若将1转化为相应的异噁唑硅醚4,再与2a～2i反应,则得到含量为86～97％的N-酰化产物5a～5i。试验表明,在DMAP催化下,3a和5a可发生O-/N-酰基转移反应。

The aeylation of 5-methyl-3-hydroxyisoxazole(1) with 3-methyl-2-(4'-chlorophenyl) butyryl chloride (2a) has been studied under different reaction conditions. Synthetic methods, solvents, acid-binding agents and reagent stoichiometry exhibit significant influence on the ratio of O-/N- acylation products of 1.O-or N-regioselective acylations of 1 have been developed. Acylation of 1 in the presence of triethylamine in acetonitrile yielded O-acylated regioisomers 3a～3e with content 88～96％. The trimethylsilyl enol ether of 1 reacted with acid chloride 2a～2i in benzene to afford N-acylated regioisomers 5a～5i with content 86～96％.It was also found that acyl-transfer between O-and N-atom on products occurred in the presence of DMAP.