Issue 9, 2012

Facile construction of densely functionalized 4H-chromenes via three-component reactions catalyzed by l-proline

Abstract

Three-component reactions of salicylaldehydes, 1,3-cyclohexanediones and a sulfur, carbon, or nitrogen-based nucleophile were developed, for the first time, by using L-proline as a catalyst, which generated various substituted 4H-chromene derivatives in good to excellent yields. The reactions were performed in ethanol under mild and metal-free conditions. In these reactions, the use of L-proline as a catalyst was proven to be key for rendering the reactions possible because replacing L-proline with other acids or bases resulted in the generation of many side products. Many nucleophiles, such as thiophenols, mercaptans, indoles, sulfinic acid, benzotriazole, 2-naphthol, 5-methyl-2-phenyl-1,2-dihydropyrazol-3-one, 6-aminouracil, 6-amino-1,3-dimethyl-1,2,3,4-tetrahydropyrimidine-2,4-dione and some commonly used C–H acids including 4-hydroxycoumarin, 2-hydroxy-1,4-naphthoquinone and barbituric acid could be successively used to assemble with dimedone and salicylaldehyde. Particularly, the product generated from the reaction of benzotriazole, 3-methoxysalicylaldehyde and dimedone can also be used as a starting material, in which the fragment of benzotriazole acts as a leaving group, for the synthesis of some important compounds by reacting with many carbon-based nucleophiles, such as dibenzoylmethane, ethyl benzoylacetate, 1,3-cyclohexanedione, N,N-dimethylaniline, 2-methylfuran and sesamol in acidic conditions. This offers a complementary route to access some 4H-chromenes that cannot be attained with the above-mentioned three-component reactions.

Graphical abstract: Facile construction of densely functionalized 4H-chromenes via three-component reactions catalyzed by l-proline

Supplementary files

Article information

Article type
Paper
Submitted
02 May 2012
Accepted
13 Jun 2012
First published
13 Jun 2012

Green Chem., 2012,14, 2421-2428

Facile construction of densely functionalized 4H-chromenes via three-component reactions catalyzed by L-proline

M. Li, B. Zhang and Y. Gu, Green Chem., 2012, 14, 2421 DOI: 10.1039/C2GC35668F

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements