Malonate, enolates, reaction with palladium, acetates

Among the nucleophiles that add exo to coordinated dienes are aUcoxides, amines, azide, acetates, halides, and stabilized carbon enolates, such as malonates and /3-diketones. The alkoxide addition is reversible if the product is treated with HCl. With a few nucleophiles, double addition reactions are observed. Acetate will react with 1,5-cod in the presence of Pb(OAc)4 and palladium salts to give a bicyclic product from addition of two acetate groups, both exo (equation 43). 

Z)-2-butenylene dicarbonate with dimethyl malonate gives a low yield (20—40%) of 2-vinylcyclopropane-l,l-dicarboxylate with up to 70% ee (Scheme 2-38) [54], Reaction with methyl acetoacetate or acetylacetone takes place in a different manner to give a dihydrofuran derivative (59% ee), which results from nucleophilic attack of enolate oxygen at the cyclization step, (c) Asymmetric elimination of an acetyl-acetate ester gives (R)-4-rerr-butyl-l-vinylcyclohexene of up to 44% ee (Scheme 2-39) [55]. (d) Palladium-catalyzed allylic silylation is also applied to asymmetric synthesis... 

A variation in this approach used the lithium enolate of diethyl malonate in a reaction with the allylic acetate moiety in 1.187. Malonate anion reacted with an intermediate 7c-allyl palladium species [formed from the allylic acetate moiety in 1.187, catalyzed hy the palladium (0) species] to give ethyl 6-(N-Boc amino)-7-(4-benzyloxypheny l)-2-carboethoxyhept-4-enoate, 1.188. ... 

Chiral phosphinous amides have been found to act as catalysts in enantio-selective allylic alkylation. Horoi has reported that the palladium-catalyzed reaction of ( )-l,3-diphenyl-2-propenyl acetate with the sodium enolate of dimethyl malonate in the presence of [PdCl(7i-allyl)]2 and the chiral ligands 45 gave 46 in 51-94% yields and up to 97% ee (Scheme 38). It is notorious that when the reaction is carried out with the chiral phosphinous amide (S)-45a, the product is also of (S) configuration, whereas by using (R)-45b the enantiomeric (R) product is obtained [165]. 

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