Can simple enones be useful partners for the catalytic stereoselective alkylation of indoles?

被引：74

作者：

Bandini, M ^{[1
]}

Fagioli, M ^{[1
]}

Garavelli, M ^{[1
]}

Melloni, A ^{[1
]}

Trigari, V ^{[1
]}

Umani-Ronchi, A ^{[1
]}

机构：

[1] Dipartimento Chim G Ciamician, I-40126 Bologna, Italy

来源：

JOURNAL OF ORGANIC CHEMISTRY | 2004年 / 69卷 / 22期

关键词：

D O I：

10.1021/jo0487202

中图分类号：

O62 [有机化学];

学科分类号：

070303 ; 081704 ;

摘要：

A new catalytic system for the first example of enantioselective Friedel-Crafts-type (FC) addition of indoles to simple enones is described. The use of an equimolar amount of chiral [AI(salen)Cl] and 2,6-lutidine (10 mol %) was found to be effective in promoting the conjugate addition of indoles to (E)-arylcrotyl ketones, furnishing the corresponding beta-indolyl ketones in excellent yield and high enantioselectivity (ee up to 89%). The role of the base was investigated through spectroscopic as well as computational analyses, which suggested that in situ formation of a new chiral (base(.)[Al(salen)]) complex was operating under our reaction conditions. In particular, a stable cationic [Al(salen)] hexacoordinate trans complex with the additive base and the enone is suggested as being responsible for the stereocontrolled reaction. Finally, detailed monitoring of the reaction course was carried out showing that a conventional FC pathway induced by [Al(salen)Cl] acting as a Lewis acid is operating.

引用

页码：7511 / 7518

页数：8

共 82 条

[1] New versatile route to the synthesis of tetrahydro-β-carbolines and tetrahydro-pyrano[3,4-b]indoles via an intramolecular Michael addition catalyzed by InBr3 [J].