Lithium divinyl cuprates

Lithium divinyl cuprates. The addition of. inylic cuprates to chiral -y-alkoxy-a,p-unsaturated ketones and esters proceeds with high diastercoselectivity the major product is that in which the vinyl group is anti to the ally lie alkoxyl group. The geometry of the unsaturated system docs not affect the stcrcocheiiiistry of the addition. 

Ipsenol (3), the pheromone of bark beetles, has been synthesized by conjugate addition of lithium divinyl cuprate to the allenic ketone (I). -... 

Lithium(3,3-dimethyl-l-butynyl)-l,l-di-ethoxy-2-piopenyl cuprate, 300 Lithium dimethyl cuprate, 301-302 Lithium di-n-octylcuprate, 356 Lithium diphenylphosphide, 302 Lithium (fl-(E)-propenyl cuprate, 302-303 Lithium divinyl cuprate, 190 Lithium-Ethylamine, 284-286, 472 Lithium fluoride, 244 Lithium hexamethyidisilazide, 337 Lithium B-isopinocampheyl-9-borabi-cycloj 3.3.1) -nonyl hydride, 303 Lithium N-isopropylcyclohexylamide, 169 Lithium o-lithiobenzylate, 67 Lithium (l-lithiopropionate, 303 Lithium methyl mercaptide, 303-304 Lithium methylthioformaldinc, 305 Lithium naphthalenide, 303, 305-306 Lithium perchlorate, 212 Lithium n-propylmercaptide, 283 Lithium selenophenolate, 306-307 Lithium 2,2,6,6-tetramethylpiperidide, 299, 307-308... 

Ethyl 2,3-epoxypropanoate is a very interesting chiron. It may be opened by various organometallic compounds such as dialkyl, diaryl, and divinyl lithium cuprates, dialkylmagnesium cuprates, trialkylalanes and aluminum acetylides.5 6 The epoxide ring is attacked regiospecifically at the p-position and produces a-hydroxy esters exclusively without racemization. The same result is observed with... 

The common starting material 32, derived from known lactam 31 [25], was treated with divinyl lithium cuprate to afford the adduct 33 as a single isomer. The stereoselectivity of this addition reaction can be explained by A(l 3) strain and stereoelectronic effect[26] the same as our recent investigations. On the other hand, deprotection of the TBDPS... 

The a-(carboethoxy)vinyl cuprate (84), generated by conjugate addition of lithium cyanomethylcuprate to ethyl propiolate, reacts with a,jS-unsaturated acid chlorides to form divinyl ketones. Subsequent Nazarov-type cyclization, now shown to be promoted by trimethylsilyl iodide, yields highly substituted cyclopentenones (Scheme 43)." ... 

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