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Synthesis 2005(10): 1601-1604  
DOI: 10.1055/s-2005-865289
PAPER
© Georg Thieme Verlag Stuttgart · New York

New Efficient Synthesis of 6,7,8,9-Tetrahydro-benzothieno[2,3-d]-1,2,4-triazolo[1,5-a]pyrimidin-10(3H)-ones via a Tandem Aza-Wittig/Heterocumulene-Mediated Annulation

Ming-Wu Ding*, Nian-Yu Huang, Hong-Wu He*
Key Laboratory of Pesticide & Chemical Biology, Ministry of Education, College of Chemistry, Central China Normal University, Wuhan, 430079, P. R. China
Fax: +86(27)67862041; e-Mail: ding5229@yahoo.com.cn;
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Publication History

Received 2 December 2004
Publication Date:
07 April 2005 (online)

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Abstract

The carbodiimides 2, obtained from aza-Wittig reactions of iminophosphorane 1 with aromatic isocyanates, reacted with hydrazine to give selectively 3-amino-2-arylamino-5,6,7,8-tetrahydro-benzothieno[2,3-d]pyrimidin-4(3H)-ones 4. Reactions of 4 with triphenylphosphine, hexachloroethane and Et3N produced iminophosphoranes 5. A tandem aza-Wittig reaction of iminophosphorane 5 with isocyanate, acyl chloride or CS2 generated 6,7,8,9-tetrahydro-benzothieno[2,3-d]-1,2,4-triazolo[1,5-a]pyrimidin-10(3H)-ones 7, 9 or 11 in satisfactory yields.

Key words

aza-Wittig reaction - benzothieno[2,3-d]pyrimidin-4(3H)-one - benzothieno[2,3-d]-1,2,4- triazolo[1,5-a]pyrimidin-10(3H)-ones - triazole - iminophosphorane