Organocuprates lithium

Reactions with cyclopropene.11 Lithium organocuprates react with the cyclo-propenone ketal 1 (12, 152-154) to form a copper species (a) that behaves as an enolate of a cyclopropanone. Thus it reacts with alkyl halides to form cis-2,3-disubstituted derivatives of 1. 

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). 

RCu-MXn, but Alexakis and coworkers163-179 showed that the chelate-controlled product (127) was obtained regiospecifically with lithium organocuprates, RaCuLi (equation 48). 

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

Simple and phenylated alkynes were prepared from alkenyl iodonium salts and lithium organocuprates. 

All the starting materials were very easily prepared in a single-pot operation by treatment of the alkoxy-allene 96 [70] with lithium organocuprate either in Et20 (for the formation of the Z- vinyl copper intermediate Z-97) or in THF (for the formation of the -vinyl copper intermediate -97) and trapping the resulting alkenyl copper E- and Z-97 with different unsaturated alkyl halides to give 98a-j (Scheme 35) [71]. 

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

Besides the expected 1,2- and 1,4-acrylate adducts, an unexpected product is also obtained in a 52% yield from 1,3-cycloheptadienemonooxirane with a mixed lithium organocuprate (Eq. 267). ... 

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... 

An extension was reported215 of the preparation of 11 -substituted compounds (242) through reaction of A9 (11>-5,10-epoxides with lithium organocuprates.216 A... 

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. 

---