From 4,5,6,7-tetrahydroindole to functionalized furan-2-one–4,5,6,7-tetrahydroindole–cyclobutene sequence in two steps

Ethyl 3-(4,5,6,7-tetrahydroindol-2-yl)propynoate, readily available from 4,5,6,7-tetrahydroindole and ethyl bromopropynoate, when treated with dichlorodicyanobenzoquinone (DDQ) in methanol affords furan-2-one–4,5,6,7-tetrahydroindole–cyclobutene sequence in a 52% yield. As kinetic and minor products...

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Bibliographic Details
Published in:Tetrahedron 2011-07, Vol.67 (26), p.4832-4837
Main Authors: Sobenina, Lyubov N., Stepanova, Zinaida V., Ushakov, Igor’ A., Mikhaleva, Al’bina I., Tomilin, Denis N., Kazheva, Ol’ga N., Alexandrov, Grigorii G., Dyachenko, Oleg A., Trofimov, Boris A.
Format: Article
Language:English
Subjects:
Alcohols
Isomers
Methyl alcohol
Reaction kinetics
Tetrahedrons
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Summary:Ethyl 3-(4,5,6,7-tetrahydroindol-2-yl)propynoate, readily available from 4,5,6,7-tetrahydroindole and ethyl bromopropynoate, when treated with dichlorodicyanobenzoquinone (DDQ) in methanol affords furan-2-one–4,5,6,7-tetrahydroindole–cyclobutene sequence in a 52% yield. As kinetic and minor products, a furan-2-one isomer along with bicycloheptadienone have been either isolated or identified. The reaction has been shown to proceed via the isolable intermediate the [2+2]-cycloadduct of ethyl 3-(4,5,6,7-tetrahydroindol-2-yl)propynoate with DDQ. Other alcohols react with the [2+2]-cycloadduct in a similar way. The effect of the alcohol structure on the products ratio has been analyzed. All the intermediates and products are formed as single diastereomer, thus indicating a concerted character of the rearrangement. [Display omitted]
ISSN:0040-4020
1464-5416
DOI:10.1016/j.tet.2011.05.018