Additions lithium phenylthio cuprate

Interesting and useful variations in R involve more complex alkyllithium reagents. For example, the treatment of (3-iodoenone (10) with lithium phenylthio(2-vinylcyclopropyl)cuprate gave the conjugate addition product (11) as an intermediate en route to the bicyclic dienone (12 82% equation 9).35 The ability of a cuprate to deliver a functionalized group to the enone was a definite advantage in this synthetic scheme. 

Lithium (cyelopropyl)(phenylthio) cuprate (l).27 This cuprate is prepared by addition of cyclopropyllithium to phenylthiocopper in THF at -78- — 20°. It converts /J-iodo enones (2) into /1-cyclopropyl enones (3) in excellent yield, even when 2 is substituted at the a-position by a methyl group. The products are useful because they rearrange when heated to annelated cyclopentenes (4 and/or 5). The rearrangement is particularly efficient when R = H, and results in 5 as the major product ( 85% yield). 

The use of the mixed lithium phenylthio(alkyl)cuprates, PhSCuRLi, for conjugate addition to a,p-un-saturated carbonyl compounds is well known. - The reaction of phenylthiocuprates derived from Grignard reagents with cinnamates and crotonates has also been reported (Scheme 50). ... 

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 n butyl (phenylthio) cuprate has been used in nucleophilic substitution reactions of arenesulfonyl fluorides, al-lylic acetates, 9 BBN, propargyllc carbamates, and bromo-alkenes, as well as in nucleophilic additions to acetoxy-epoxides. It Is a good choice for 1,4-addItIon of an n-Bu group, having been used in 1,4 addition-elimination reactions of a-oxoketene dithloacetals and 3-halo-2-cycloalkenones, and in tandem vicinal dialkylation reactions of 5-methyleneoxa-zolones and alkynes. A typical example Is the use of the reagentin the stereospecific synthesis of (, -2-heptenoicacidfrom acetylene (eq 1). ... 

Preparative Methods lithium (phenylthio) (trimethyistanny -cuprate (2) is prepared by the addition of soiid phenyithiocop-per(I) to a THF solution of trimethylstannyilithlum (1) (eq 1). 

CONJUGATE ADDITIONS Bis(methylthio)(trimethylsilyl)methyllithium. Diethylalum-inum cyanide. Di(a-methoxyvinyl)copperlithium. Ethyl diethoxyacetate. Ethyl methylsulfinylacetate. Lithium a-carboethoxy vinyl(l-hexynyl)cuprate. Potassium fluoride. Quinine, chinchonine. Titanium tetrachloride. Trimethylaluminum. Tris-(phenylthio)methyllithium. 

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