Lithium dibutylcuprate

Penten 2 one Lithium dibutylcuprate Now see if you can identify the second possibility... 

Addition of lithium dibutylcuprate (3 equiv) to 8 provides the corresponding trans-fi-lactam 9 exclusively15. 

Excellent selectivities are also observed with (CH,)2CuZnCl, Bti2CiiTi[OCH(CH3)2], and BnCu BF3. The reaction of a standard cuprate reagent, e.g., lithium dibutylcuprate, with ( )-l in tetrahydrofuran gives predominantly the SN2 product. 

The configuration at sulfur is mainly responsible for the sense of asymmetric induction. It is of interest to note that butylcopper and lithium dibutylcuprate undergo addition reactions in the opposite stereochemical sense. The adducts can be converted to chiral /i-disubstituted carboxylic acids1. 

Lithium dibutylcuprate reacted with ( )-l, 3-butadienyl p-tosyl sulfone affording (Z)-2-octenyl p-tosyl sulfone. In the reaction of allyl ( )- and (Z)-l, 3-dibutadienyl sulfones with lithium dibutylcuprate or lithium (Z)-di(l-butenyl) cuprate, the major compound obtained was of (Z)-geometry around the 2,3-double bond, indicating that (Z)-selectivity is not so high in this reaction (56-79%)408-... 

Similarly, the synthesis of (+)-T-7 (129) was achieved in a five-step sequence from [2R-(2R)]-22l in 32% overall yield (Scheme 8). The regioselective opening of the epoxide of [2R-(2R)]-223 with lithium dibutylcuprate afforded alcohol [2R-(2R)]-227 that was transformed in a three-step sequence into (+)-T-7 (129) in 51% yield. In an analogous way (+)-T-8 (126) was obtained from [2R-(2S)] 223 in four steps and 35% yield. 

Lithium diallylcuprate, 11 Lithium dibutylcuprate, 61 Lithium dimethylcuprate, 63, 258 Sakurai reaction Alkylaluminum halides, 5 Allyltrimethylsilane, 11, 305 Titanium(IV) chloride, 304 with other organometallic agents (IS, 2S) -2-Amino-3-methoxy-1 -pheny 1-1-propanol, 17... 

Lithium dialkylcuprates-Boron trifluoride etherate, 208 Lithium dibutylcuprate-Boron trifluoride etherate, 208 Lithium dimethylcuprate-Boron trifluoride etherate, 208 Lithium tri-sec-butylborohydride, 21, 167, 248... 

Lithium dialkylcuprates-Boron trifluoride etherate, 208 Lithium diallylcuprate, 11 Lithium dibutylcuprate, 61, 208, 344 Lithium dibutylcuprate-Boron trifluoride etherate, 208 Lithium dimethylcuprate, 63, 151, 258 Lithium dimethylcuprate-Boron trifluoride etherate, 208 Organocopper reagents, 11, 61, 63, 131, 151, 207, 344 Organocopper reagents-Boron trifluoride etherate, 208 Organolithium reagents-Copper(I) halides, 58... 

A complete set of 13C kinetic isotope effects determined (by a natural abundance CMR method) for addition of lithium dibutylcuprate to cyclohexenone, in THF at —78°C, have been shown to be consistent with those calculated theoretically for ratedetermining reductive elimination from an intermediate square-planar copper complex.120 Thus, die KIE (12k/13k) = 1.020-1.026 at C(3) is indicative of substantial bonding change, and partial alkyl transfer can explain the significant low KIE = 1.011-1.016 for Ca of die butyl group. 

Alkyl p-toluenesul fonates react with lithium dialkylcuprates in the same way that alkyl halides do. Treatment of the preceding p-toluenesulfonate with lithium dibutylcuprate gives the desired compound. 

As actually performed, a 91% yield of the desired product was obtained in the reaction of the p-toluenesulfonate with lithium dibutylcuprate. 

Aldol reactions of aldehydes with the -stannyl a-selanyl enolate generated from 2-phenylselanylcyclopent-2-enone directly produced 2-(l-hydroxyalkyl) cyclopenten-2-ones in high yields [55] (Scheme 43, reaction l).The n-Bu3SnSePh elimination was explained by lithium aldolate assistance. The nature of the nucleophile has a dramatic effect on the stereochemistry of the 1,4-addition products isolated after protonolysis. The use of lithium dibutylcuprate afforded cz5-compounds, whereas Me3SiLi or, better, a mixed silylcuprate, furnished the trans-isomers as the major products [56] (Scheme 43, reaction 2). 

On the other hand, enantioselective conjugate addition to 2-cyclohexenone with lithium dibutylcuprates (having a noncova-lently bound chiral phosphorus ligand derived from ephedrine) affords 3-butylcyclohexanone with up to 76% ee (eq 14). ... 

Kim has also studied the corresponding acylation of homocuprates by S-(2-pyridyl) thioates, discussed earlier in the context of total synthesis of monensin and erythronolide A (Sections 1.13.2.2 and 1.13.3.2). Under the standard anaerobic conditions necessary for cuprate formation, good yields of ketones could be derived from acylation of lithium dimethylcuprate (or lithium dibutylcuprate) by S-(2-pyridyl) thiobenzoate and other simple S-(pyridyl) thiol esters (equation 71). Interestingly, if the homocuprate is intentionally placed under an oxygen atmosphere before acylation and then reacted with the S-(2-pyridyl) thioate in oxygen at -78 C, one obtains good yields of the ctnresponding ester (equation 72). 

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