Synlett 2012; 23(18): 2699-2703
DOI: 10.1055/s-0032-1317485
letter
© Georg Thieme Verlag Stuttgart · New York

Brønsted Acid Catalyzed Friedel–Crafts Alkylation Reactions of Trifluoro­methyl-α,β-ynones with Indoles

Shigeru Sasaki*
Institute of Medicinal Chemistry, Hoshi University, 2-4-41 Ebara, Shinagawa, Tokyo 142-8501, Japan   Fax: +81(3)54985768   Email: s-sasaki@hoshi.ac.jp
,
Yuta Ikekame
Institute of Medicinal Chemistry, Hoshi University, 2-4-41 Ebara, Shinagawa, Tokyo 142-8501, Japan   Fax: +81(3)54985768   Email: s-sasaki@hoshi.ac.jp
,
Manabu Tanayama
Institute of Medicinal Chemistry, Hoshi University, 2-4-41 Ebara, Shinagawa, Tokyo 142-8501, Japan   Fax: +81(3)54985768   Email: s-sasaki@hoshi.ac.jp
,
Takayasu Yamauchi
Institute of Medicinal Chemistry, Hoshi University, 2-4-41 Ebara, Shinagawa, Tokyo 142-8501, Japan   Fax: +81(3)54985768   Email: s-sasaki@hoshi.ac.jp
,
Kimio Higashiyama
Institute of Medicinal Chemistry, Hoshi University, 2-4-41 Ebara, Shinagawa, Tokyo 142-8501, Japan   Fax: +81(3)54985768   Email: s-sasaki@hoshi.ac.jp
› Author Affiliations
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Publication History

Received: 18 August 2012

Accepted after revision: 25 September 2012

Publication Date:
18 October 2012 (online)


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Abstract

The successful development of a Brønsted acid catalyzed Friedel–Crafts alkylation reaction between trifluoromethyl-α,β-ynones and indoles has been described. The reaction is catalyzed by benzoic acid (5 mol%), with the indoles adding to the carbonyl carbon of the trifluoromethyl-α,β-ynones producing the corresponding 1,2-addition products as trifluoromethyl propargyl alcohols in high yields. Furthermore, treatment of the product with indoles in the presence of trifluoroacetic acid (10 mol%) afforded trifluoro­methyl-functionalized unsymmetrical bis(indolyl)propynes in high yields.

Supporting Information