Lithium diphenylcuprate

Reaction of lithium diphenylcuprate with optically active 2 bromobutane yields 2 phenylbu tane with high net inversion of configuration When the 2 bromobutane used has the stereostruc ture shown will the 2 phenylbutane formed have the R or the S configuration" ... 

Lithium bis(2-butyl)cupiate [Lithium bis-(l-methylpropyl)cuprate, 55, 112 Lithium dialkylcuprates, 55, 112 Lithium dimethylcuprate, 55, 112 Lithium diphenylcuprate, 55,112 LITHIUM DIPROPENYLCUPRATE, 55, 103,111... 

The viabihty of this synthetic approach to the introduction of a carboxylic acid fimction at C2 has been demonstrated in two ways. Following lithium diphenylcuprate addition to 564, the newly introduced phenyl group is subsequently degraded by ozonolysis to provide 567. Alternatively, reaction of 564 with diethylaluminium cyanide in toluene gives 568 which is also conveniently transformed into 567... 

A chiral synthesis of stegobinone (SSS) is based on the cleavage of (25,35)-2,3-epoxybutane with lithium diphenylcuprate, which occurs with complete inversion. The resulting chiral alcohol is converted into the mixed anhydride, which is used to acylate the... 

Furthermore, no reduction products were isolated from a similar reaction between tra i-j3-bromostyrene and lithium diphenylcuprate, although considerable copper-halogen exchange probably occurred. 

Gilman reported in 1952 that addition of one equivalent of Meli to a Cu salt results in the formation of yeUow precipitates which then afford colorless solutions upon addition of another equivalent of MeLi (Scheme 10.2) [18]. In 1966, Costa isolated a complex between phenylcopper(I) and magnesium as weU as crystals of a lithium diphenylcuprate(I) complex [19]. Although the organocopper reagents derived from Grignard reagents are widely used and may be described as R CuM j the extent to which to this reflects the reality in solution is still uncertain. 

Another extensively studied polycycle is the tricyclo[3.3.0.0 ]octan-3-one system 19 which can be converted to 8-methylbicyclo[3.3.0]octan-3-one derivatives 20 upon treatment with lithium dimethylcuprate. Lithium diphenylcuprate reacted in the same way." " ... 

Selenenyl halides also react similarly with copper enolates, aluminum enolates, and zirconium enolates [101]. Scheme 15.38 illustrates the selenenylation of copper enolates generated by conjugate addition of lithium diphenylcuprate to cyclo-pentenone [100 d]. 

Lithium diphenylcuprates and lithium dialkylcuprates reacted similarly with alkynylphenyl iodonium tosylates to afford phenyl- and alkyl-substituted alkynes respectively... 

Lithium di- -butylcuprate reacts with 121 to produce (5)-( + )-2-methylhexanoic acid (130) with 98% inversion of the stereo center. Similarly, lithium diphenylcuprate gives (5)-( + )-2-phenylpropionic acid (131) with 95% inversion. Yields for this process are generally low, however [47]. 

Most of the organocuprate -addition-a-alkylations of cyclopent-l-enones and cyclohex-2-enones have involved introduction of the nucleophilic -substituent and the electrophilic a-substituent preferentially in a trans-configuration. In contrast lithium diphenylcuprate addition to cyclopent-2-enone followed by a-alkylation involves attachment of the two new groups stereoselectively in a cis-relationship, even though such c/s-2-alkyl-3-phenylcyclopentanones are less stable than their trans-epimers [equation (14)]. ... 

This is a very general reaction in that primary, secondary, and tertiary alkyl halides react with primary, secondary, or tertiary organocuprates. The halide can be a chloride, a bromide, or an iodide, but iodides are more reactive than bromides, which are more reactive than chlorides. Another example is the reaction of 49 with lithium diphenylcuprate to give 50. The reaction of alkyl halides and organocuprates is the preferred method for coupling an alkyl halide to an organometallic compound. Many different hydrocarbons can be prepared. 

Whitesides et al. (1969a) have made a detailed study of the coupling reaction and found that (+)-(/ )-2-bromobutane enters into the reaction with lithium diphenylcuprate with predominant inversion (84-92%) of stereochemistry. Alkyl tosylates can also be used as substrates (Whitesides et al.. 

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