β-Acylation of Ethyl Pyrrole-2-carboxylate by Friedel-Crafts Acylation : Scope and Limitations (Synthetic Studies on Indoles and Related Compounds. XXXVIII)

Masanobu TANI; Takahiro ARIYASU; Chika NISHIYAMA; Hiroko HAGIWARA; Toshiko WATANABE; Yuusaku YOKOYAMA; Yasuoki MURAKAMI

doi:10.1248/cpb.44.48

β-Acylation of Ethyl Pyrrole-2-carboxylate by Friedel-Crafts Acylation : Scope and Limitations (Synthetic Studies on Indoles and Related Compounds. XXXVIII)

Masanobu TANI, Takahiro ARIYASU, Chika NISHIYAMA, Hiroko HAGIWARA, Toshiko WATANABE, Yuusaku YOKOYAMA, Yasuoki MURAKAMI

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Keywords: pyrrole, acylation, Friedel-Crafts reaction, regioselective, ethoxycarbonyl, trichloroacetyl

JOURNAL FREE ACCESS

1996 Volume 44 Issue 1 Pages 48-54

DOI https://doi.org/10.1248/cpb.44.48

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Abstract

The Friedel-Crafts acylation of ethyl pyrrole-2-carboxylate (3) was studied under several conditions using various Lewis acids and acyl chlorides. The acylation with various acyl chlorides in the presence of aluminum chloride gave exclusively ethyl 4-acylpyrrole-2-carboxylate (5), whereas weaker Lewis acids such as zinc chloride and boron trifluoride etherate gave a mixture of ethyl 4- and 5-acylpyrrole-2-carboxylates.

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