Cyclohexa-2,4-dienones cycloaddition with

MOBs reactive with cyclohexa-2,4-dienones undergo Diels-Alder cycloadditions with [60]fullerene to produce hitherto unknown, stable, and highly functionalized bicyclo-[2.2.2]-octenone derivatives. In light of the mild conditions and considerable generality, these reactions are certainly noteworthy... 

Bis-allylic oxidation of 23 and related cyclohexa-1,4-dienes provides a convenient and general preparation of cyclohexa-2,5-dien-l-ones (Scheme 7). These cross-conjugated die-nones are substrates for a variety of photochemical rearrangement and intramolecular cycloaddition reactions. Amide-directed hydrogenations of dienones 24a and 24b with the homogeneous iridium catalyst afford cyclohexanones 25a and 25b, containing three stereogenic centers on the six-... 

The normally sluggish Diels-Alder cycloaddition between cyclohexa-1,3-diene and various enones and enals can be activated by precoordination of the diene to a jt-basic molybdenum complex TpMo(NO)MeIm(//-cyclohexadiene)].134 The 4-1-2-cycloaddition of cyclohexa-2,4-dienones with electron-deficient 2n -dienophiles produced bridged bicyclo[2.2.2]octenones. Triplet-sensitized irradiation of these bridged bicyclooctenones produced bicyclo[3.3.0]octanoids, whereas direct irradiation yielded bicyclo[4.2.0]octanes.135... 

The oxidative dearomatization of ort/io-substituted phenols 225 leads to 6,6-disubstituted cyclohexa-2,4-dienones 226 (Scheme 3.92), which can be conveniently utilized in situ as dienes in the Diels-Alder cycloaddition reaction. When the oxidation of phenols is performed in the absence of an external dienophile, a dimerization via [4-f2] cycloaddition often occurs spontaneously at ambient temperature to afford the corresponding dimers with an extraordinary level of regio-, site- and stereoselectivity [348-350]. A detailed experimental and theoretical investigation of such hypervalent iodine induced Diels-Alder cyclodimerizations... 

SCHEME 19 A novel periselective cycloaddition of cycloheptatriene with cyclohexa-2,4-dienones. 

Singh, V. and Porinchu, M., A novel periselective cycloaddition of cycloheptatriene with cyclohexa-2,4-dienones, Tetrahedron iMt., 34, 2817,1993. 

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