Conjugate addition double metallation

Physical and Chemical Properties. The (F)- and (Z)-isomers of cinnamaldehyde are both known. (F)-Cinnamaldehyde [14371-10-9] is generally produced commercially and its properties are given in Table 2. Cinnamaldehyde undergoes reactions that are typical of an a,P-unsaturated aromatic aldehyde. Slow oxidation to cinnamic acid is observed upon exposure to air. This process can be accelerated in the presence of transition-metal catalysts such as cobalt acetate (28). Under more vigorous conditions with either nitric or chromic acid, cleavage at the double bond occurs to afford benzoic acid. Epoxidation of cinnamaldehyde via a conjugate addition mechanism is observed upon treatment with a salt of /-butyl hydroperoxide (29). 

The l ,J -DBFOX/Ph-transition metal aqua complex catalysts should be suitable for the further applications to conjugate addition reactions of carbon nucleophiles [90-92]. What we challenged is the double activation method as a new methodology of catalyzed asymmetric reactions. Therein donor and acceptor molecules are both activated by achiral Lewis amines and chiral Lewis acids, respectively the chiral Lewis acid catalysts used in this reaction are J ,J -DBFOX/Ph-transition metal aqua complexes. 

Aziridines can add to carbon—carbon multiple bonds. Elevated temperature and alkali metal catalysis are required in the case of nonpolarized double bonds (193—195). On the other hand, the addition of aziridines onto the conjugated polarized double or triple bonds of a,p-unsaturated nitriles (196—199), ketones (197,200), esters (201—205), amides (197), sulfones (206—209), or quinones (210—212) in a Michael addition-type reaction frequendy proceeds even at room temperature without a catalyst. The adducts obtained from the reaction of aziridines with a,p-unsaturated ketones, eg, 4-aziridinyl-2-butanone [503-12-8] from 3-buten-2-one, can be converted to 1,3-substituted pyrrolidines by subsequent ring opening with acyl chlorides and alkaline cyclization (213). 

The importance of transition-metal-catalysed reactions lies in their ability to facilitate reactions that would not occur under normal conditions. One such reaction is nucleophilic attack on an isolated double bond. While the presence of a conjugating group promotes the attack of nucleophiles, in its absence no such reaction occurs. Coordination of an alkene to a transition metal ion such as pal-ladium(II) changes its reactivity dramatically as electron density is drawn towards the metal and away from the n orbitals of the alkene. This leads to activation towards attack by nucleophiles just as for conjugate addition and unusual chemistry follows. Unusual, that is, for the alkene the palladium centre behaves exactly as expected. 

Addition of Phosphorus Nucleophiles to C=C Bonds Phosphorus nucleophiles, both neutral and anionic, undergo addition to activated carbon—carbon double bonds. Such reactions constitute a phosphorus analogous of the conjugate addition, and they are often referred to as phospha-Michael addition. For hydrophosphonylation of inactivated double bonds, radical conditions are a viable option. In the last 15 years, however, an attractive alternative of a transition-metal-catalyzed hydrophosphonylation has also emerged. ... 

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