Development of an Efficient Procedure for Indole Ring Synthesis from 2-Ethynylaniline Derivatives Catalyzed by Cu(II) Salts and Its Application to Natural Product Synthesis
作者:Kou Hiroya、Shin Itoh、Takao Sakamoto
DOI:10.1021/jo035528b
日期:2004.2.1
The development of efficient methods for the indole synthesis catalyzed by Cu(II) salts and its applications were investigated. Cu(OAc)2 has been proved to be the best catalyst for the synthesis of various 1-p-tolylsulfonyl or 1-methylsulfonylindoles, which have both electron-withdrawing and electron-donating groups on the aromatic ring and C2 position of indoles. For the primary aniline derivatives
The cyclization reaction of various 2-ethynylanilines, which were easily synthesized from 2-haloanilines by the palladium-catalyzed reaction with terminal alkynes, with tetrabutylammonium fluoride (TBAF) to yield 2-substituted indoles proceeded at refluxing or room temperature in THF in excellent yields without affecting the bromo, chloro, cyano, ethoxycarbonyl, and ethynyl groups.
SbF5−MeOH catalytic system efficiently promotes the alkyne−carbonyl metathesis of o-alkynylaniline derivatives and aldehydes to afford 2,3-disubstituted dihydroquinolinones in moderate to high yields with high trans-selectivity.
One-Pot Approach to 2,3-Disubstituted-2,3-dihydro-4-quinolones from 2-Alkynylbenzamides
作者:Noriko Okamoto、Kei Takeda、Minoru Ishikura、Reiko Yanada
DOI:10.1021/jo201636a
日期:2011.11.4
3-disubstituted-2,3-dihydro-4-quinolones have been achieved via tandem Hofmann-type rearrangement of 2-alkynylbenzamides, nucleophilic addition of alcohols to the isocyanate intermediates, intermolecular [2+2]-cycloaddition with carbon–carbontriple bonds and aldehydes, and intramolecular aminocyclization of nitrogen of carbamates to the α,β-unsaturated ketones.
An efficient strategy has been developed for the synthesis of indole derivativescontaining the tetrazole moiety using a AuCl3-catalyzed cyclization reaction. The precursors of the cycloadduct were easily prepared by an Ugi-azide 4-CR in methanol at room temperature. The merit of this protocol lies in its operational simplicity, readily available starting materials, high yields of product, and good