Synthesis and anomalous structure–reactivity relationship of 8,11-dichloro[5]metacyclophan-3-one
作者:Daniël S van Es、Norbert Gret、Marianne de Rijke、Maurice J van Eis、Franciscus J.J de Kanter、Willem H de Wolf、Friedrich Bickelhaupt、Stephan Menzer、Anthony L Spek
DOI:10.1016/s0040-4020(01)00239-3
日期:2001.4
The synthesis, structural characterisation, and reactivity of the title compound are reported. It was prepared in order to investigate the effects of incorporation of an sp(2)-centre in the bridge of a [5]metacyclophane on its structure and reactivity. An X-ray crystal structure of the cyclophanone demonstrates that the benzene ring is distorted to the same extent as in the hydrocarbon parent compound, while there is less strain in the bridge. Nevertheless, the cyclophanone displays a reduced reactivity in Diels-Alder reactions, which is tentatively ascribed to transition state effects. Calculations indicate that in spite of the close proximity between the ketone functionality and the benzene ring, there are no pi-pi interactions between them. (C) 2001 Elsevier Science Ltd. All rights reserved.
A practical and effective copper-catalyzed dehydrogenative Diels–Alderreaction of gem-diesters and ketone with dienes has been established. The active dienophiles were generated in situ via a radical-based dehydrogenation process, which reacted with a wide variety of dienes to afford various polysubstituted cyclohexene derivatives in good to excellent yields.