Synthesis 2007(4): 590-596  
DOI: 10.1055/s-2007-965874
PAPER
© Georg Thieme Verlag Stuttgart · New York

Synthesis of 6H-Thieno[3,2-b]pyridin-7-ones from N-(2-X-Carbonyl)-3-thienyl Ketenimines (X = RS, ArO, R2N) via Consecutive [1,5]-X Sigmatropic Rearrangement and 6π-Electrocyclization

Mateo Alajarín*, Ángel Vidal*, María-Mar Ortín
Departamento de Química Orgánica, Facultad de Química, Universidad de Murcia, Campus de Espinardo, 30100 Murcia, Spain
Fax: +34(968)364149; e-Mail: alajarin@um.es;
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Received 6 September 2006
Publikationsdatum:
08. Januar 2007 (online)

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Abstract

N-(2-X-Carbonyl)-3-thienyl ketenimines (X = RS, ArO, R2N) undergo cyclization under thermal conditions, through a [1,5]-X sigmatropic rearrangement followed by a 6π-electrocyclic ring closure of the resulting intermediate ketene, to provide 6H-thieno[3,2-b]pyridin-7-ones, bearing alkylthio, arylthio, aryloxy or amino groups at their 5-position.

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For examples of methods of preparation of thieno[3,2-b]pyridines, see reviews cited in reference 1.