Synthesis and Photochemistry of 5,5-Dimethyl-1H-pyrrol-2(5H)-one and of SomeN-Substituted Derivatives
作者:Andreas Ihlefeld、Paul Margaretha
DOI:10.1002/hlca.19920750435
日期:1992.6.24
In two steps, 5,5-dimethyl-1H-pyrrol-2(5H)-one (3a) was prepared from 5,5-dimethylpyrrolidine-2,4-dione ( = dimethyltetramic acid; 4) in 71% overall yield (Scheme 1) and further converted to N-substituted derivatives 3b–fvia acylation, alkylation, or methoxycarbonylation of its anion (Scheme 2). The substituents on the N-atom exert a strong influence on the photochemical reactivity ([2 + 2] photocycloaddition
在两个步骤中,由总含量为71%的5,5-二甲基吡咯烷-2,4-二酮(=二甲基四甲酸; 4)制备了5,5-二甲基-1 H-吡咯-2(5 H)-one(3a)。(方案1),然后通过其阴离子的酰化,烷基化或甲氧基羰基化进一步转化为N-取代的衍生物3b-f(方案2)。N-原子上的取代基对这些氮杂烯酮-3的光化学反应性([2 + 2]光环加成至2,3-二甲基丁-2-烯,光环二聚化,光还原)有很大影响(方案3)。通常,N-烷基化合物的反应比(N-未取代的)标题化合物3a或其N-乙酰基和N-(甲氧羰基)衍生物3e和3f分别慢得多且效率较低。这些化合物的行为与先前研究的相应内酯5,5-二甲基-2(5 H)-呋喃酮相似。