Preparation of Alkyl-Substituted Indoles in the Benzene Portion. Part 9. Synthesis of (1aS,8bS)-1-tert-Butyloxycarbonyl-8-formyl-1,1a,2,8b-tetrahydroazirino(2',3':3,4)pyrrolo(1,2-a)indole. Model Study for the Enantiospecific Synthesis of Aziridinomitosenes.
作者:Iwao UTSUNOMIYA、Masahiro FUJI、Tomohiro SATO、Mitsutaka NATSUME
DOI:10.1248/cpb.41.854
日期:——
Effective pathways for an enantiospecific synthesis of (1aS, 8bS)-1-tert-butyloxycarbonyl-8-formyl-1, 1a, 2, 8b-tetrahydroazirino[2', 3' : 3, 4]pyrrolo[1, 2-α]indole (8) were investigated as a preliminary experiment aiming at chiral syntheses of aziridinomitosenes 5 and (1aS, 8bS)-8-[[(aminocarbonyl)oxy]methyl]-5-formyl-7-hydroxy-1, 1a, 2, 8b-tetra-hydroazirino[2', 3' : 3, 4]pyrrolo[1, 2-α]indone (6a). An aldehyde 14, derived from L-serine was condensed with 2-lithio-1-(phenylsulfonyl)indole (10) to afford diastereomers 15a and 15b, whose stereochemistry was unambiguously determined by 1H-NMR studies of the 1, 3-dioxane derivatives 17a, 17b, and 18 as well as the X-ray crystallographic analysis of a dihydropyrrolo[1, 2-α]indole derivative 31a. The latter compound was prepared from 15a via the following operations(Chart 5) : (i) removal of the acetonide and the indole-protecting groups, followed by acetylation to form 29a, (ii) Vilsmeier reaction to produce 30a, and (iii) hydrolysis of acetyl groups, partial methanesulfonylation (mesylation), and treatment with potassium carbonate in acetonitrile. A diastereomer 31b was obtained from 15b in a similar manner.Both isomers 31a and 31b afforded the desired compound 8 upon treatment with a mesylation reagest followed by potassium tert-butoxide in tetrahydrofuran.
研究了对映体特异性合成 (1aS, 8bS)-1-ter-butyloxycarbonyl-8-formyl-1, 1a, 2, 8b-tetrahydroazirino[2', 3' :作为手性合成氮丙啶甲糖苷 5 和 (1aS, 8bS)-8-[[(aminocarbonyl)oxy]methyl]-5-formyl-7-hydroxy-1, 1a, 2, 8b-tetra-hydroazirino[2', 3' : 3, 4]pyrrolo[1,2-α]indone(6a)的初步实验,研究了氮丙啶甲糖苷 5 和 (1aS, 8bS)-8-[[(aminocarbonyl)oxy]methyl]-5-formyl-7-hydroxy-1, 1a, 2, 8b-tetra-hydroazirino[2', 3' : 3, 4]pyrrolo[1,2-α]indone(6a)。通过对 1,3-二氧六环衍生物 17a、17b 和 18 的 1H-NMR 研究,以及对二氢吡咯并[1,2-α]吲哚衍生物 31a 的 X 射线晶体学分析,明确确定了它们的立体化学结构。后一种化合物是由 15a 通过以下步骤制备的(图 5):(i) 去除丙酮和吲哚保护基团,然后进行乙酰化反应生成 29a;(ii) 维尔斯梅尔反应生成 30a;(iii) 乙酰基水解、部分甲磺酰化(甲磺酰化),然后在乙腈中用碳酸钾处理。异构体 31a 和 31b 在四氢呋喃中用甲磺酰化试剂和叔丁醇钾处理后,均可得到所需的化合物 8。