Stereoselective Alkylation of Indole with 5-Arylidene-Meldrum’s Acids in the Presence of Organocatalysts
Abstract
Background: Indole motif is frequently present in biologically active compounds. Enantiomerically pure or enriched 2,2-dimethyl-5-(aryl(1H-indol-3-yl)methyl)-1,3-dioxane-4,6-diones can be considered as a convenient starting point for the synthesis of a indole ring fused with cyclic ketones with biological activity. Preparation of chiral 2,2-dimethyl-5-(aryl(1H-indol-3-yl)methyl)-1,3-dioxane- 4,6-diones requires the reaction of indole with 2,2-dimethyl-5-arylidene-1,3-dioxane-4,6-diones in the presence of chiral catalysts or other source of chiral induction. Methods: Enantioselective Friedel-Crafts alkylation of indole has been performed with 2,2-dimethyl-5- arylidene-1,3-dioxane-4,6-diones in the presence of organocatalysts to give 5-((1H-indol-3- yl)(aryl)methyl)-2,2-dimethyl-1,3-dioxane-4,6-diones. Broad scope of organocatalysts as well as various temperatures and solvents used for the reaction were tested. Results: 2,2-Dimethyl-5-(aryl(1H-indol-3-yl)methyl)-1,3-dioxane-4,6-diones were obtained with quantitative yield and enantiomeric ratio 1:3 using thiourea organocatalyst. Also a new spectroscopic method for discrimination of 5-((1H-indol-3-yl)(aryl)methyl)-2,2-dimethyl-1,3-dioxane-4,6-diones enantiomers was developed. Conclusion: Enantioselective Friedel-Crafts alkylation of indole has been developed. In the presence of thiourea catalysts, 2,2-dimethyl-5-arylidene-1,3-dioxane-4,6-diones react with indole to give 2,2- dimethyl-5-(aryl(1H-indol-3-yl)methyl)-1,3-dioxane-4,6-diones with good yields and reasonable ee.
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- Category:
- Articles
- Type:
- artykuł w czasopiśmie wyróżnionym w JCR
- Published in:
-
LETTERS IN ORGANIC CHEMISTRY
no. 15,
pages 883 - 890,
ISSN: 1570-1786 - Language:
- English
- Publication year:
- 2018
- Bibliographic description:
- Makowiec S., Janikowska K., Zakaszewska A., Najda-Mocarska E.: Stereoselective Alkylation of Indole with 5-Arylidene-Meldrum’s Acids in the Presence of Organocatalysts// LETTERS IN ORGANIC CHEMISTRY. -Vol. 15, nr. 10 (2018), s.883-890
- DOI:
- Digital Object Identifier (open in new tab) 10.2174/1570178615666180503150327
- Sources of funding:
- Verified by:
- Gdańsk University of Technology
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