Vinyl cuprates preparation

Z)-Viuylic iodides. These iodides can be prepared by reaction of iodine with (Z)-vinylic cuprates, prepared by addition of lithium dialkylcuprates to acetylene (equation I). ... 

This reaction illustrates a stereoselective preparation of (Z)-vinylic cuprates, which are very useful synthetic intermediates. They react with a variety of electrophiles such as carbon dioxide, epoxides, aldehydes, allylic halides, alkyl halides, and acetylenic halides they undergo... 

Vinyl cuprates.17 Vinyl cuprates can be prepared conveniently by in situ trans-metallation of vinylstannanes, available by hydrostannylation of alkynes, with a cuprate such as (CH3)2Cu(CN)Li2 (equation I). Reagents prepared in this way effect conjugate addition of the vinyl group to an enone with essentially no transfer of the methyl group. 

Travoprost is an isopropyl ester of fluprostenol, which shows an lOP-reducing effect as potent as latanoprost [69], The synthetic route of travoprost 31 is shown in Scheme 4 [70], The cleavage of the three-membered ring of tricyclic ketone 26 by the attack of the cuprate prepared from vinyl iodide 25 gave the compound 27. 

The above-described problem demonstrates the first enantioselective synthesis of dysidiolide, a C25 isoprenoid antimitotic agent. The central transformations are the sulfenylation-dehydrosulfenylation sequence to prepare an a,/5-tnone, the biomimetic cationic 1,2-rearrangement to form stereoselectively the bicyclic scaffold, vinyl cuprate displacement of an iodide furnishing the C-l side chain and the photochemical oxidation of furan to generate the j hydroxy-butenolide functionality. 

This reaction illustrates a stereoselective preparation of (Z)-vinylic cuprates, 5 which are very useful synthetic Intermediates. They react with a variety of electrophiles such as carbon dioxide,5,6 epoxides,5,6 aldehydes,6 allylic halides,7 alkyl halides,7 and acetylenic halides 7 they undergo conjugate addition to a,6-unsaturated esters,5 6 ketones,6 aldehydes,6 and sulfones.8 Finally they add smoothly to activated triple bonds6 such as HCSC-OEt, HC3C-SEt, HC=C-CH(0Et)2. In most cases these cuprates transfer both alkenyl groups. The uses and applications of the carbocupration reaction have been reviewed recently.9 The configurational purity in the final product 1s at least 99.951 Z in the above transformations. 

We have already seen examples of cuprates being used in stereochemically controlled conjugate additions to cyclopentenones and similar results can be achieved with ate complexes of vinyl alanes prepared by hydroalumination of alkynes to give e.g. 179 R = hexyl and hence the anti-A-product43 182. 

Vinylic cuprates. Marek el al.1 have prepared the versatile vinyl cuprate I, which can function as the dianion of acrolein. 

Vinylcuprates.11 Vinylcupratcs (2) that can also undergo substitution reactions can be prepared as shown in equation (11). These vinyl cuprates can convert a 1-alkyne... 

Lithium phenylthio[(a-diethoxymethyl)vinyl] cuprate, (I). Mol. wt. 308.84. Preparation ... 

The stereochemistry of the migrating group is retained. Moreover, vinyl cuprates are readily prepared from acetylenes [5m, 6,7]. 

Z)-Ethylenic mixed anhydrides are easily prepared without isomerization and react with vinyl cuprates (and other organometallics) under Pd° catalysis with >99% stereochemical control to give unsymmetrical divinyl ketones (eq 18). Alternative routes via (Z)-ethylenic acyl chlorides produce ( /Z) mixtures. 

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