Preparation of Alkyl-Substituted Indoles in the Benzene Portion. Part 13. Enantiospecific Synthesis of Mitosene Analogues Related to FR 900482 and FR 66979.
作者:Iwao UTSUNOMIYA、Hideaki MURATAKE、Mitsutaka NATSUME
DOI:10.1248/cpb.43.37
日期:——
An acid-catalyzed indole formation reaction previously reported by us was successfully applied to the preparation of variously substituted 4-hydroxy-1H-indoles 11a-g having carbon and/or heteroatom substituents at the benzene portion of the indole ring, using as substrates 3-(4, 4-dialkoxy-1-oxobutyl)-1H-pyrroles 10a-g, which are readily available from simple pyrroles in several steps. Employing one of these indoles, 11g, as a starting intermediate, an enantiospecific synthesis of the mitosene analogues 8, 9a and 9b related to antitumor antibiotics FR 900482 (1) and FR 66979 (2) was achieved by i) condensation of 20 with a chiral aldehyde 21, ii) transformation of 22a and 22b into the tricyclic compounds 29a and 29b, iii) introduction of the additional one-carbon unit as a formyl group, iv) formation of the aziridine ring, and v) removal of the benzyl protecting group. Elimination of the tert-butyloxycarbonyl group was also examined to provide the basis for a future project to synthesize 5a, the cross-linkage product of 2 and DNA.
以 3-(4,4-二烷氧基-1-氧代丁基)-1H-吡咯 10a-g 为底物,成功地制备了在吲哚环的苯部分具有碳和/或杂原子取代基的各种取代的 4-羟基-1H-吲哚 11a-g。利用其中一个吲哚 11g 作为起始中间体,通过 i) 20 与手性醛 21 缩合,实现了与抗肿瘤抗生素 FR 900482 (1) 和 FR 66979 (2) 相关的丝裂原类似物 8、9a 和 9b 的对映体特异性合成、ii) 将 22a 和 22b 转化为三环化合物 29a 和 29b,iii) 引入额外的一碳单元作为甲酰基,iv) 形成氮丙啶环,v) 去除苄基保护基。此外,还对叔丁氧羰基的消除进行了研究,为今后合成 2 和 DNA 的交联产物 5a 的项目奠定了基础。