Enolate anions, cyano esters, reaction with

While the addition/oxidation and the addition/protonation procedures are successful with ester enolates as well as more reactive carbon nucleophiles, the addition/acylation procedure requires more reactive anions and the addition of a polar aprotic solvent (HMPA has been used) to disfavor reversal of anion addition. Under these conditions, cyano-stabilized anions and ester enolates fail (simple alkylation of the carbanion), but cyanohydrin acetal anions are successful. The addition of a cyanohydrin acetal anion to l,4-dimethoxynaphthalene-Cr(CO)3 occnrs by kinetic control at C-/3 in THF/HMPA and leads to the O -diacetyl derivative after methyl iodide addition and hydrolysis of the cyanohydrin acetal. Monoacylation of 1,4-dimethoxynaphthalene-Cr(CO)3 has been achieved nsing the seqnence of reactions shown in eqnation (126). ... 

Michael Reaction (Section 19.8A) A Michael reaction involves the addition of a weakly basic nucleophile to a carbon-carbon double bond made electrophilic by conjugation with the carbonyl group of an aldehyde, a ketone, or an ester or with a nitro or cyano group. The mechanism of the Michael reaction involves initial formation of an enolate anion in base and attack of the enolate nucleophile at the )3-carbon of the Michael acceptor to create a new resonance-stabilized enolate anion intermediate that is protonated on oxygen to create an enol and regenerate the base then tautom-erization to the keto form completes the reaction. The base is catalytic in the Michael reaction. 

Oxaziridines 14 transfer the NCOY group to enolates of ketones (see Eq. 90),153-156 esters (see Eq. no),153 155 157 158 amides,158 A -acyloxazolidino-nes,153,157 and (3-dicarbonyl compounds,155 anions stabilized by cyano (see Eq. 141),155 sulfonyl (see Eq. 145),158 and phosphinoyl154 groups, and ketone enol ethers.155 Yields are in the 20-60% range. The first step in these reactions is presumably attack of the enolate on nitrogen as in Eq. 11, followed by elimination of an aldehyde ArCHO and formation of the animation product. With esters,... 

Hoye and Crawford (94JOC520) have reported the reaction of several enolates 145 derived from esters and amides as well as a-sulfonyl-, a-cyano-, and a-phosphonyl-substituted anions with cyclic sulfate 144 to give hydroxylated product 146. The nucleophilic attack occurred at the terminal carbon [Eq. (31)]. 

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