Unsaturated carbonyl com

Michael addition of an allylic carbanion to an a, -unsaturated carbonyl com-... 

The conjugate addition of an amine to an a,p-unsaturated carbonyl com-pound/nitrile has been achieved in water without any catalyst at room temperature (Scheme 5.15). The rate acceleration of the reaction was explained by H-bonding of H2O to the amine and carbonyl group of alkene. 

The strong Lewis acids HC(py)3M (NO)2 (M = Mo, W) (see also Section 14.3.1), with Lewis acidities comparable with that of BF3, were shown by Faller et al. to coordinate and activate a,/8-unsaturated carbonyl compounds via formation of an M-O a-bond. These complexes, in nitromethane, catalyze Diels-Alder reactions with dienes (e.g. butadiene). They also readily polymerize butadiene when a less basic dienophile com-... 

The photocycloaddition of triplet benzophenone to norbornene has been originally reported by Scharf and Korte (Sch. 30) [94]. The photoproduct 101 which is formed in high cxo-selectivity could be thermally cleaved to the 5,8-unsaturated ketone 102, an application of the carbonyl-olefm-metathesis (COM) concept [95]. 

The photocycloaddition of triplet benzophenone to norbornene was originally reported by Scharf and Korte. The photoproduct 101 that is formed in high exo-selectivity could be thermally cleaved to the 5,e-unsaturated ketone 102, an appHcation of the carbonyl-olefin metathesis (COM) concept. The 1,4-biradical formed in the interaction of norbornene with o-dibenzoyl-benzene was trapped in an intramolecular fashion by the second carbonyl moiety. A highly regioselective reaction of triplet benzophenone was reported with 5-methylenenorborn-2-ene, with preferential attack toward the exo CC double bond. A number of publications have discussed the photocycloaddition reactions of triplet carbonyl compounds to norbornadiene and quadricyclane, as weU as the competition between the Paterno-Biichi reaction and the sensitized norbornadiene/quadricyclane interconversion. Oxetane formation has also been reported for the photoreaction of biacetyl and para-quinones with benzvalene. ... 

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