Synthesis 2015; 47(17): 2545-2548
DOI: 10.1055/s-0034-1381054
special topic
© Georg Thieme Verlag Stuttgart · New York

Synthetic Studies toward Bi-linderone Lead To Unexpected 6π-Electrocyclization Reactions: A Facile Construction of Highly Congested Spiro Compounds

Fenfen Xiao
School of Chemistry & Material Science, Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of Ministry of Education of China, Northwest University, Xi’an 710127, P. R. of China   Email: wyx27210@nwu.edu.cn   Email: xiangdonghu@nwu.edu.cn
,
Qing Zhang
School of Chemistry & Material Science, Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of Ministry of Education of China, Northwest University, Xi’an 710127, P. R. of China   Email: wyx27210@nwu.edu.cn   Email: xiangdonghu@nwu.edu.cn
,
Yunxia Wang*
School of Chemistry & Material Science, Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of Ministry of Education of China, Northwest University, Xi’an 710127, P. R. of China   Email: wyx27210@nwu.edu.cn   Email: xiangdonghu@nwu.edu.cn
,
Xiangdong Hu*
School of Chemistry & Material Science, Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of Ministry of Education of China, Northwest University, Xi’an 710127, P. R. of China   Email: wyx27210@nwu.edu.cn   Email: xiangdonghu@nwu.edu.cn
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Further Information

Publication History

Received: 29 May 2015

Accepted after revision: 29 June 2015

Publication Date:
11 August 2015 (online)

Abstract

During synthetic studies toward bi-linderone, unexpected 6π-electrocyclizations of 4,5-dimethoxy-2-[(E)-1,3-dimethoxy-5-phenylpenta-2,4-dienylidene]cyclopent-4-ene-1,3-dione and 2-[(E)-1-hydroxy-3-methoxy-5-phenylpenta-2,4-dienylidene]-4,5-dimethoxycyclopent-4-ene-1,3-dione were observed. The cyclization of 4,5-dimethoxy-2-[(E)-1,3-dimethoxy-5-phenylpenta-2,4-dienylidene]cyclopent-4-ene-1,3-dione gave a rare example of a 6π-electrocyclization reaction that occurs readily at room temperature in the presence of silica gel. Meanwhile, the intramolecular hydrogen bonding existing in 2-[(E)-1-hydroxy-3-methoxy-5-phenylpenta-2,4-dienylidene]-4,5-dimethoxycyclopent-4-ene-1,3-dione afforded a strong contribution to the stability of the flat conformation, and this hampered the 6π-electrocyclization process. These 6π-electrocyclizations afforded a facile approach to highly congested spiro compounds.

Supporting Information

 
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