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Synthesis 2010(17): 2965-2968  
DOI: 10.1055/s-0030-1258160
PAPER
© Georg Thieme Verlag Stuttgart ˙ New York

Direct Bromination of Ethyl 5-Alkylthiophene-2-carboxylates

Ilya V. Taydakov*a, Sergey S. Krasnoselskiyb
a G. S. Petrov Institute of Plastics, JSC, Perovskiy proezd 35, Moscow 111024, Russian Federation
Fax: +7(495)6000603; e-Mail: taidakov@gmail.com;
b People’s Friendship University of Russia, Miklukho-Maklaya str. 9, Moscow 117198, Russian Federation
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Publikationsverlauf

Received 20 April 2010
Publikationsdatum:
07. Juli 2010 (online)

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Abstract

Approaches to brominated thiophene-2-carboxylic acids by electrophilic bromination of the corresponding acids and esters were compared and investigated. A synthetic route was developed involving direct bromination of ethyl 5-alkylthiophene-2-carboxylates followed by saponification of the resulting ethyl 5-alkyl-4-bromothiophene-2-carboxylates. The key bromination step is selective in dichloromethane solution at 0-5 ˚C and furnishes the corresponding ethyl 5-alkyl-4-bromothiophene-2-carboxylates in excellent yields. No migration or isomerization of the alkyl substituents was observed.

Key words

bromine - esters - thiophenes - electrophilic aromatic substitutions - aluminum

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