Construction of Highly Substituted Nitroaromatic Systems by Cyclocondensation. Part I. Synthesis of 4-nitro-3-oxobutyrate
作者:Rudolf O. Duthaler
DOI:10.1002/hlca.19830660516
日期:1983.7.27
Methyl 4-nitro-3-oxobutyrate (1) is prepared by substitution of 4-bromo- and 4-iodo-3-oxobutyrate enol ether or enol acetate derivatives with nitrite and deprotection of the keto function (Schemes 2 and 3). A much more convenient access to 1 is, however, the nitration of acetoacetate dianion with alkyl nitrates (Scheme 4). Compound 1 is stable and storable, and can be handled safely. Its use in cyclocondensations
4-硝基-3-氧代丁酸乙酯(1)是通过4-溴-和取代制备的4-碘代-3-氧代丁酸烯醇醚或与亚硝酸盐和酮官能团脱保护(烯醇乙酸酯衍生物方案2和3)。然而,更方便地获得1是用烷基硝酸盐硝化乙酰乙酸二阴离子(方案4)。化合物1稳定且可储存,可以安全处理。通过与乙酰丙酮反应建立其在环缩合中的应用(方案5),以70%的产率提供4,6-二甲基-3-硝基水杨酸酯48。卤素取代法合成1还可以访问该结晶(ë)烯醇醚18的1,以及它的二甲基缩醛25,(Ž)烯醇醋酸盐32,和(ë)烯醇乙酸酯33。由4-溴-3-氧代丁酸酯12制备3-取代的4-溴丁烯酸酯15、16和26,这是使用N-溴-琥珀酰亚胺的现有方法的有用替代品。