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Synfacts 2010(7): 0750-0750  
DOI: 10.1055/s-0029-1220140
Synthesis of Heterocycles
© Georg Thieme Verlag Stuttgart ˙ New York

Gallium-Catalyzed Synthesis of 1,3-Dihydrobenzo[c]thiophenes

Contributor(s): Victor Snieckus, Alcides da Silva
H. Zhou*, D. Zhu, Y. Xie, H. Huang, K. Wang
Zhejiang University, Hangzhou, P. R. of China
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Publication History

Publication Date:
22 June 2010 (online)

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Significance

A sulfur-assisted sequential reaction wherein in situ generated vinyl allenes undergo an intramolecular [4+2] cycloaddition of diynes 1 in the presence of Ga(OTf)3 followed by aromatization to give 1,3-dihydrobenzo[c]thiophenes 2 has been developed. Optimized mild reaction conditions give the 1,3-dihydrobenzo[c]thio­phenes 2 in moderate to good yields. The scope of the reaction was investigated. The presence of R² = electron-withdrawing group, for example ketone, is essential for the isomerization processes. A possible mechanism was proposed.