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Five-membered ring annelation in [2.2]paracyclophanes by aldol condensation.

ABSTRACT: Under basic conditions 4,5,12,13-tetraacetyl[2.2]paracyclophane (9) cyclizes by a double aldol condensation to provide the two aldols 12 and 15 in a 3:7 ratio. The structures of these compounds were obtained from X-ray structural analysis, spectroscopic data, and mechanistic considerations. On acid treatment 12 is dehydrated to a mixture of the condensed five-membered [2.2]paracyclophane derivatives 18-20, whereas 15 yields a mixture of the isomeric cyclopentadienones 21-23. The structures of these elimination products are also deduced from X-ray and spectroscopic data. The sequence presented here constitutes the simplest route so far to cyclophanes carrying an annelated five-membered ring.

SUBMITTER: Hopf H

PROVIDER: S-EPMC4168897 | biostudies-literature | 2014

REPOSITORIES: biostudies-literature

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Five-membered ring annelation in [2.2]paracyclophanes by aldol condensation.

Hopf Henning H Narayanan Swaminathan Vijay SV Jones Peter G PG

Beilstein journal of organic chemistry 20140828

Under basic conditions 4,5,12,13-tetraacetyl[2.2]paracyclophane (9) cyclizes by a double aldol condensation to provide the two aldols 12 and 15 in a 3:7 ratio. The structures of these compounds were obtained from X-ray structural analysis, spectroscopic data, and mechanistic considerations. On acid treatment 12 is dehydrated to a mixture of the condensed five-membered [2.2]paracyclophane derivatives 18-20, whereas 15 yields a mixture of the isomeric cyclopentadienones 21-23. The structures of th ...[more]

PMID: 25246961

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