Acrylonitrile nucleophilic conjugate addition

The polarisation produced by co-ordination to the metal may be transmitted through a conjugated system. Michael addition reactions of nucleophiles to TV-bonded acrylonitrile are known, and provide a convenient method for the preparation of derivatives. A wide range of nucleophiles may be used in these conjugate additions. For example, the anion of nitromethane (generated in situ) reacts with the ruthenium(m) complex [Ru(NH3)5N=CCH=CH2)]3+, 4.6, to yield a complex of 4-nitrobutyronitrile (Fig. 4-18). 

Propose a mechanism for the conjugate addition of a nucleophile (Nuc ) to acrylonitrile (H2C = CHCN) and to nitroethylene. Use resonance forms to show how the cyano and nitro groups activate the double bond toward conjugate addition. 

Mechanistically, two scenarios have been advanced. The first involves coordination of the nitrile to the Ru center which is followed by nucleophilic attack at the nitrile, while the second entails a sequence of events starting with oxidative addition of water, an alcohol or an amine to the metal center, followed by insertion of the nitrile into the Ru-OH bond. A recent report describes the conjugate addition of alcohols to acrylonitrile compounds catalyzed by a mthenium-acetamido complex [Ru(PCy3)2(CO)(CH3CONH)-(i-PrOH)H] (7) (Scheme 10.13) [17]. The mechanistic investigation of this reaction supports the proposal that the N-coordination of acrylo-... 

Triethyl phosphite reacts with l-(l-acetoxyalkyl)acrylonitriles to give diethyl 2-cyano-2-alke-nylphosphonates in 85-94% yields as a mixture of (Z)- and (Ej-isomers. The reaction proceeds by the conjugate addition of triethyl phosphite to acrylonitrile followed by the P-elimination of acetate, which represents the nucleophile in the dealkylation step. ... 

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