Tert-Butyllithium

However, reaction of 218 (E = P, R = R = H, R = r" = Me) with rerr-butyl-lithium most probably yields 221. The phospholyl loses its electrophilicity and the iron atom bears a considerable negative charge. Addition of rerr-butyllithium (one equivalent) followed by methyl iodide (one equivalent) does not give any isolable product but leads to recovery of the starting 218 only. In excess tert-butyllithium and methyliodide, 222 (R = r-Bu, R = Me) was isolated (81IC3252). 

Treatment of sulfmylaziridine 73 (Scheme 3.23) with MeMgBr and then with tert-butyllithium gave aziridinyllithium 74, which reacted with ethyl chloroformate to afford aziridine-2-carboxylate 75 in 64% yield [70]. The reaction was stereospecific, giving 75 as a single diastereomer. 

Metalated epoxides can react with organometallics to give olefins after elimination of dimetal oxide, a process often referred to as reductive alkylation (Path B, Scheme 5.2). Crandall and Lin first described this reaction in their seminal paper in 1967 treatment of tert-butyloxirane 106 with 3 equiv. of tert-butyllithium, for example, gave trans-di-tert-butylethylene 110 in 64% yield (Scheme 5.23), Stating that this reaction should have some synthetic potential , [36] they proposed a reaction pathway in which tert-butyllithium reacted with a-lithiooxycarbene 108 to generate dianion 109 and thence olefin 110 upon elimination of dilithium oxide. The epoxide has, in effect, acted as a vinyl cation equivalent. 

H), followed by bromine-lithium exchange using 2 equivalents of tert-butyllithium to give the desired intermediate. This intermediate readily picked up carbon monoxide and work-up of the reaction mixture gave indigo (Fig. 17) (ref. 31). 

A second, more convenient approach was tried starting with dicyclopropyla-cetylene 56 [15-17] which, after deprotonation with tert-butyllithium at both propargylic positions, yielded the bisaldehyde 57 upon treatment with dimethyl-formamide. The latter was converted to the bis(dibromoethenyl) derivative 58, and this in turn to the dibromotriyne 59 by standard methods (Scheme 11) [18]. The dibromide 59 was coupled with the ethynylcyclopropylheterocuprate 50 to give the terminally bis-protected pentayne 60. 

Bromopene Propane, 2-bromo- (8) 1-Propene, 2-bromo- (9) (557-93-7) tert-Butyllithium Lithium, tert-butyl- (8) Lithium, (1,1-dimethylethy )- (19) (594-19-4)... 

MoBr(NH)(dppe)2] Br. Compound BMo was prepared by treatment of the Mo(IV) dialkylhydrazido(2-) complex [MoBr NN (C5H10) (dppe)2]Br (compound AMo) with tert-butyllithium or electrochemically at —1.62 V vs. a saturated calomel electrode... 

Reaction of N-(2-bromoallyl)-N-prop-2-ynylamines 72 with tert-butyllithium, followed by reaction with zirconocene methyl chloride and subsequent cyclization gives 1,1-lithio-zirconioalkenes 73 via 74 and intermediate 75 (Scheme 7.23) [144,145], Treatment of the lithiozirconium complex 73 with deuterated sulfuric acid leads to the trideuterated pyrrolidine 76. 

The synthetic usefulness of reactions of lithiated methoxyallene 42 with suitable electrophiles was demonstrated by several syntheses of bioactive natural products or substructures thereof [52-58]. An interesting application was described by Fall et al. [52] after addition of alkyl iodide 55 to lithiated methoxyallene 42, deprotonation by tert-butyllithium and addition of carbon dioxide occurred at the terminal y-carbon and thus provided butenolide 57 after acidic workup. Desilylation of this intermediate with TBAF finally gave bicyclic oxepane derivative 58 in good overall yield (Scheme 8.14). 

The addition of carbonyl compounds towards lithiated 1-siloxy-substituted allenes does not proceed in the manner described above for alkoxyallenes. Tius and co-work-ers found that treatment of 1-siloxy-substituted allene 67 with tert-butyllithium and subsequent addition of aldehydes or ketones led to the formation of ,/i-unsaturated acyl silanes 70 (Scheme 8.19) [66]. This simple and convenient method starts with the usual lithiation of allene 67 at C-l but is followed by a migration of the silyl group from oxygen to C-l, thus forming the lithium enolate 69, which finally adds to the carbonyl species. Transmetalation of the lithiated intermediate 69 to the corresponding zinc enolate provided better access to acylsilanes derived from enolizable aldehydes. For reactions of 69 with ketones, transmetalation to a magnesium species seems to afford optimal results. 

Although the preparation of the substituted allene ether substrates for the Nazarov reaction is not the topic of this chapter, it is necessary to mention a few aspects of their synthesis. Lithioallene 1 (Eq. 13.13) can be trapped with chlorotri-methylsilane to give 35 [6]. Exposure of 35 to sec- or tert-butyllithium leads to allenyl-lithium 36, which can be trapped with alkyl halides or other electrophiles to give 37. Desilylation of 37 leads to 38. This is somewhat laborious, but it leads to allene 38 uncontaminated by propargyl ether 39. Exposure of 39 to n-butyllithium, followed by quenching with acid, typically produces mixtures of 38 and 39 that are difficult to separate. Fortunately, one need not prepare allenes 38 in order to access the C6-sub-... 

The germaallene 194 was prepared by reaction of fluoroalkynylgermane 195 with tert-butyllithium at -78°C in about 85% yield.174 Elimination of LiF occurred at low temperature. 194 was the first allenic compound of germanium structurally characterized (Scheme 41). 

Carbodiphosphoranes (R3P = C = PR3) are known,79 but ylides with a P-H bond are rare.80 Therefore, the spectroscopic characterization of 77 was unexpected. Even more surprising was the characterization of the carbodiphosphorane 79 featuring two P-H bonds.31 This compound, prepared by treatment of 2d with tert-butyllithium, rearranged in solution at room temperature over a period of 16 h to afford the phosphorus ylide 80 with one remaining P-H bond. This compound was also unstable and transformed completely into the diphosphinomethane 81 overnight. Note that calculations for the model compounds where R = NH2 predicted 79 to be 28 kcal/mol less stable than 80, which is also 34 kcal/mol above 81.16 The surprising stability of 79 and 80 is probably due to the presence of bulky substituents, since tetracoordinate phosphorus atoms can more readily accommodate the increased steric constraints than can their tricoordinate counterparts. 

Braun et al. [258] used a combination of tert-butyllithium (t-BuLi) and tetramefhy-lethylenediamine to create initiator sites at the surface of carbon black for the LASIP of styrene. Schomaker et al. [259] first immobilized a methyl methacrylate derivative on colloidal silica and after activation by a Grignard reagent polymerized MMA. 

Bis[dimethylthienol]l,4,6,8-tetratellurafulvalene. 3,4-Dibromo-2,5 dimethylthiophene in tetrahydrofuran is treated at -78°C with 2 equiv of ferf-butyllithium. After 2 h, 1 equiv of tellurium powder is added. The mixture is slowly warmed to 0°C and kept at 0°C until all the tellurium has dissolved. The mixture is cooled again to -78°C, treated with tert-butyllithium and then with tellurium at 0°C. The ditellurolate solution is cooled to -78°C, mixed with 0.5 equiv of tetrachloroethene, stirred for 18 h and allowed to warm to 20°C. The brown solid is isolated by filtration and extracted with carbon disulphide. The extract is evaporated and the residue recrystallized from 1,1,2-trichloroethane to give bronze-coloured crystals. Yield 75% m.p. 295-298°C. 

How well an organolithium reagent fares as an exchange component depends on its basicity. Thus, tert-butyllithium outperforms iec-butyllithium, which in turn is superior to butyllithium. MethyUithium is the least reactive alkyllithium but still surpasses phenyl-lithium, at least at low concentrations, i.e. the order is ... 

Using butyllithium rather than tert-butyllithium. CioHis = 2-adamantyl. 

Using tert-butyllithium rather than butyllithium. 

Standard organolithium reagents such as butyllithium, ec-butyllithium or tert-butyllithium deprotonate rapidly, if not instantaneously, the relatively acidic hydrocarbons of the 1,4-diene, diaryhnethane, triarylmethane, fluorene, indene and cyclopentadiene families and all terminal acetylenes (1-alkynes) as well. Butyllithium alone is ineffective toward toluene but its coordination complex with A/ ,A/ ,iV, iV-tetramethylethylenediamine does produce benzyllithium in high yield when heated to 80 To introduce metal into less reactive hydrocarbons one has either to rely on neighboring group-assistance or to employ so-called superbases. 

Ethyl vinyl ether 19a and methyl vinyl ether 19b are metalated by tert-butyllithium at the oxygen-adjacent methine site. -Alkyl groups retard the reaction substantially. Thus, l-methoxy-2-methyl-2-propene was found to be inert toward all... 

General. All reactions were performed under nitrogen. H NMR and NMR spectra were recorded in ppm (5) on a 300 MHz instrument using TMS as internal standard. Elemental analyses were performed by Robertson Micolit Laboratories. Anhydrous THE, toluene, and tert-butyllithium in pentane (1.7 M) were purchased. Flash chromatography was performed with silica gel 60 (230-400 mesh). Melting points were determined and are uncorrected. 

This reagent was obtained either from Aldrich Chemical Company, Inc., or Lithium Corporation of America, Bessemer City, NC. A technical data sheet is available from the suppliers. Solutions of ca. 2 M were titrimetrically analyzed for active alkyllithium by the tosylhydrazone method. It is advisable to make certain that the organolithium reagent to be used was prepared in pentane solution. This evaluation can be easily accomplished by the gas chromatographic analysis of the organic layer obtained from the hydrolysis, under a nitrogen atmosphere, of the tert-butyllithium solution to be used. Isobutane and pentane should comprise essentially all of the... 

Mitsuwa Pure Chemicals. tert-Butyllithium was obtained from Aldrich Chemical... 

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