Lithium organocuprate reagents

Likewise, the reaction of iodonium salt 57 with lithium organocuprate reagents affords products of coupling 65 in good yields (Scheme 30) [54]. 

Amino acid synthesis.1 Optically pure amino acids can be prepared in two steps from serine, readily available as either the d- or L-enantiomer. Reaction of N-benzylserine (or of N-benzyl-N-Boc-serine) with the preformed Mitsunobu reagent in CH3CN at -55° provides the protected serine (J-lactone (2) in almost quantitative yield. The lactone reacts with lithium organocuprates (R2CuLi) to... 

Alkanes can also be prepared from alkyl halides by reduction, directly with Zn and acetic acid (AcOH) (see Section 5.7.14) or via the Grignard reagent formation followed by hydrolytic work-up (see Section 5.7.15). The coupling reaction of alkyl halides with Gilman reagent (R 2CuLi, lithium organocuprates) also produces alkanes (see Section 5.5.2). 

Lithium organocuprates are reagents for cross-coupling, conjugate addition, epoxide opening, ketone synthesis and addition to acetylenes ... 

Organolithium compounds are less reactive than lithium organocuprates. A number of publications deal with the differences observed between the two reagents in the ring-opening reaction of oxiranes. The reaction of 1,3-cyclohexadienemonooxirane with methyllithium is seen in Eq. 277. ... 

E. Organometallics — Preparation and reactions of Grignard and organolithium reagents, lithium organocuprates, and other modern main group and transition metal reagents and catalysts... 

Lithium organocupmtes. House et al. have found that certain undesirable side reactions in the preparation of lithium organocuprates can be minimized by use of this complex rather than commercial cuprous bromide itself, which apparently contains some impurities. The complex is readily prepared in 90% yield from (CH3)2 S and CuBr. It is insoluble in ether, hexane, acetone, methanol, and water, but dissolves in several solvents in the presence of excess (CH3)2S. Thus a solution of the complex in ether and (CH3)2S is used the excess sulfide is readily separated from reaction products. The soluble copper reagent t-BuC CCu can also be used instead of CuBr, but the precursor, t-butylacetylene, is expensive. The use of the complex was illustrated for reactions of (CH3)2CuLi and (CH2=CH)2CuLi. 

The most widely used reagents, however, which have been developed during the past 20 years, are the lithium organocuprates, R CuLi. They are prepared in situ, in ether or THF, by addition of two mol of alkyllithium to copper(I) halide below 0°C under a nitrogen atmosphere. It is convenient to use Me S.CuBr as this is more resistant to oxidation in air than CuBr and can thus be introduced without contamination by copper(II). 

OrganometaUic reagent (Section 6.3) Molecule that contains both carbon and a metal. Usually carbon is at least partially covalently bonded to the metal. Examples are Grignard reagents, organolithium reagents, and lithium organocuprates. 

The conjugate addition of Grignard reagents to a-phenyl-a/8-unsaturaled esters has been reported. The first example of a conjugate 1,6-addition of a lithium organocuprate to an unsaturated ester has been observed (Scheme 44) in a synthesis of a volatile constituent of Bartlett pears. 

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