Lithium dimethyl cuprate conjugate addition

The results for conjugate additions to pseudodipeptides 83 and 86 may be interpreted along similar lines. Thus, addition of the fairly slim lithium dimethyl-cuprate nucleophile proceeded non-selectively (84, Scheme 6.17) [34, 35]. Con-... 

Mori started with the early introduction of the chiral centre [298] in using (3-oxidation of pentanoic acid A by the yeast, Candida rugosa, IFO 0750 [299]. The obtained (R)-3-hydroxypentanoic acid B was transformed into C in a few conventional steps. The second building block was prepared from methyl 2-pentynoate D conjugate addition of lithium dimethyl cuprate yielded E, which was further converted into the frans-configured vinyl bromide F. Hydro-boration of C yielded G which upon Suzuki s palladium catalysed cross-coupling with F furnished 157 after treatment of the reaction product with hydrochloric acid followed by chromatographic purification. The synthesis of ent-157 used (S)-3-hydroxypentanoic acid. 

Charge acceleration has also been observed in the rearrangement of 2-allyloxy-2-cyclo-hexenones. In comparison to the silyl enol ether derivative of 2-allyloxy-3-methyl-2-cyclo-hexenone, the lithium cuprate derivative obtained by conjugate addition of lithium dimethyl-cuprate rearranges much faster. This effect has been explained by the intermediacy of an allyl radical/oxyoxaallyl radical anion (semi-dione) pair84. 

CONJUGATE ADDITION Alkylmethyl-magncsiocuprates. 2-Carboethoxyl-benzyl phenyl sulfoxide. Cyanodiethyl-aluminum chloride. 1-Cyclopropyl-l-tiimethylsilyloxyethylene. Lithium 1,3-butadiene-l-olate. Lithium dimethyl-cuprate. Magnesium ethyl malonate. Potassium carbonate. Tri-n-butyl-stannyllithium. Trimethylzinclithium. 

Conjugate addUion-cyclization. 3-Substituied 2-carbomethoxycyclopentanones are prepared conveniently in one step from dimethyl (2E)-hexenedioate by conjugate addition of lithium dialkyl cuprates or higher-order cyan[Pg.348]

Alternative preparations of 2-allyl-3-methylcyclohexanone include a) lithium-ammonia reduction of 2-allyl-3 methylcyclohex-2-enone (see Note 13), which can be prepared by alkylation of 3-methjdcyclohex-2-enone or by alkjdation of 4-carboethoxy-3-methylcyclohex-2-enone [Hagemann s ester 2-Cyclohexene-l-carboxylic acid, 2-inethyl-4-oxo-, ethyl ester], followed bj hydrolysis and decarboxylation and b) conjugate addition of lithium dimethylcupratc [Cuprate (1-), dimethyl-, lithium] to 2-cyolohexen-l-one followed by trapping of the enolate with allyl iodide or allyl bromidein an appropriate solvent. 

CONJUGATE ADDITION Diethyl acetylmethylmalonate. Dilithium trimethyl cuprate. N,N-Dimethylbenzeneselenenamide. Dimethyl sulfoxide. Lithium di-(2-vinylcyclo-propyl)cuprate. Lithium phenylthio(cyclopropyi)cuprate. Lithium phenylthio[(a-diethoxymethyl)vinyi]cuprate. 2-(2-Mcthoxy)-aIiylidene-l,3-dithiane. 2-Nitropropene. Tetra- -butylammonium fluoride. Titanium(IV) chloride -is(methyithio)methyl-lithium. 

Lithium dimethyl copper reacted with (186) to introduce a methyl group stereo-selectively trans to the 5-isopropyl group. The enolate anion (187) so formed underwent intramolecular alkylation to give the cis-decalone(188), which was reduced to d/-valerane (189). Conjugate addition of lithium methyl vinyl cuprate to cyclopent-2-... 

Conjugate Addition Reactions. The cuprate and zincate reagents lithium bis[dimethyl(phenyl)silyl]cuprate (75583-57-2) and lithium dimethyl[dimethyl(phenyl)silyl]-zincate (100112-20-7) are usually used in conjugate addition reactions, but PhMe2 SiLi can be used with catalytic amounts of dimethylzinc (eq More resistant substrates may employ the zincate produced in situ, with catalytic amounts of copper(I) additives, and aided by the cocatalyst Sc(OTf)3 (eq 18). ... 

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