Stereoselectivity control by oxaspiro rings during Diels-Alder cycloadditions to cross-conjugated cyclohexadienones: the syn oxygen phenomenon

K Ohkata, Y Tamura, BB Shetuni, R Takagi…

Index: Ohkata, Katsuo; Tamura, Yukiko; Shetuni, Brandon B.; Takagi, Ryukichi; Miyanaga, Wataru; Kojima, Satoshi; Paquette, Leo A. Journal of the American Chemical Society, 2004 , vol. 126, # 51 p. 16783 - 16792

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Citation Number: 24

Abstract

The diastereofacial selectivity operating in Diels-Alder additions involving spirocyclic cross- conjugated cyclohexadienones with dienes of varying reactivity has been investigated. The study has included the ether series 1a-c as well as the lactone/ketone pair 2a/2b. In all cases, the preferred [4+ 2] cycloaddition pathway consisted of bonding from that π-surface syn to the oxygen atom. 4-Substituted-4-methyl-2, 5-cyclohexadienones (monocyclic ...