H-butyllithium

Competitive metallation experiments with IV-methylpyrrole and thiophene and with IV-methylindole and benzo[6]thiophene indicate that the sulfur-containing heterocycles react more rapidly with H-butyllithium in ether. The comparative reactivity of thiophene and furan with butyllithium depends on the metallation conditions. In hexane, furan reacts more rapidly than thiophene but in ether, in the presence of tetramethylethylenediamine (TMEDA), the order of reactivity is reversed (77JCS(P1)887). Competitive metallation experiments have established that dibenzofuran is more easily lithiated than dibenzothiophene, which in turn is more easily lithiated than A-ethylcarbazole. These compounds lose the proton bound to carbon 4 in dibenzofuran and dibenzothiophene and the equivalent proton (bound to carbon 1) in the carbazole (64JOM(2)304). 

In an effort to demonstrate the synthetic utility of vinyliodonium salts, small-scale reactions of (4-rm-butyl-1 -cyclohexenyl)phenyliodonium tetrafluoroborate (62) with various nucleophilic species, especially copper(I) reagents, have been conducted125,126. The copper(I)-assisted reactions include the conversions of 62 to 1-cyano-, 1-halo-, 1-alkyl- and 1-phenyl-4-ter r-butylcyclohexenes (equation 215). The alkylation and phenylation of the cyclohexenyl ligand in 62 with lithium diorganocuprates is noteworthy, since the treatment of 62 with H-butyllithium leads to fragmentation of the iodonium ion and affords only a 0.2% yield of 1 -w-butyl-4-terr-butylcyclohexene (equation 216)126. 

Quinolizinium ions fused with indole are related to yohimbine alkaloids flavopereirine, sempervirine, reserpine, alstoniline, ajmaline, and so on. Parent indolo[2,3-a]quinolizinium salt (272) has been reported (87TL5259). l-Phenylsulfonyl-2-(2-pyridyl)indole 271 was treated with H-butyllithium to afford the 3-lithio species, which was quenched with bromoacetalde-hyde to give the cyclization product (48%). It was dehydrated with aq. NaOH to afford 272 (89%). Using this method, sempervirine (273) was obtained (88T3195). 

Solutions of basic organometallic reagents such as H-butyllithium can be stored in an Erlenmeyer flask provided with a device for the introduction of inert gas while... 

Lithium diisopropylamide can effect C-2-deprotonation of 3-halofurans. With furoic acid and two equivalents of lithium diisopropylamide, selective formation of the lithium carboxylate/5-lithio compound is found, whereas H-butyllithium, via ort/jo-assistance, produces the lithium carboxylate/3-lithio derivative. ... 

As in pyrroles, the A-hydrogen in indoles is much more acidic (pAa 16.2) than that of an aromatic amine, say aniline (pAa 30.7). Any very strong base will effect complete conversion of an A-unsubstituted indole into the corresponding indolyl anion, amongst the most convenient being sodium hydride, H-butyllithium, or an alkyl Grignard reagent. 

In reactions requiring palladium(O), formation of the active complex may be achieved more conveniently by reduction of a palladium(ll) complex, for example Pd(0Ac)2. Any phosphine may then be used in the reaction, without the need to synthesize and isolate the corresponding palladium(0)-phosphine complex.The reduction of palladium(ll) to pal-ladium(O) can be achieved with amines, phosphines, alkenes, and organometallics such as DIBAL-H, butyllithium, or trialkylaluminium. The mechanisms are worth surveying as they illustrate the basic steps of organometallic chemistry. 

Subtle structural differences have been observed in some dimers of lithiated 1,3-bis[(dimethylamino)alkyl]benzenes [14]. Direct lithiation of l,3-bis[(dimethylami-no)ethyl]henzens with H-butyllithium produced a symmetric dimer, in which the coordination sphere of lithium was saturated by coordination of the chelating amino substituents. An analogous lithiation reaction performed between 1,3-bis[(dimethylamino)/ ro 7y/]benzene and n-butyllithium yielded a mixed dimeric aggregate comprising the expected phenyllithium derivative and nBuLi in a 1 1 molar ratio. In the molecular structure four lithium ions and four bridging carbon atoms form a ladder-type framework. 

To a solution of 0.40 mol of butyllithium in about 280 ml of hexane were added 280 ml of dry THF with cooling below -10°C. Subsequently 0.40 mol of 1,1-diethoxy--2-propyne (see Chapter V, Exp. 28) was introduced in 15 min at -30 to -10°C. To the solution obtained was then added in 15 min with cooling at about -15°C 0.40 mol of chloromethyl ethyl ether (note 2). After the addition stirring was continued for 1 h without cooling. The mixture was then shaken with concentrated ammonium chloride solution and the ethereal layer was separated off. The aqueous layer was extracted twice with diethyl ether. After drying the ethereal solutions over magnesium sulfate the diethyl ether was evaporated in a water-pump vacuum. 

TO a solution of 0.10 mol of phenyl acetyl one (commercially available, see also Ref. 1) in 100 ml of dry THF was added a solution of 0.21 mol of butyllithium in about 145 ml of hexane. During this addition the temperature was kept below -20°C. The obtained solution was cooled to -65°C and a solution of 0.12 mol of KO-tert.--CijHg (commercially available, see Chapter IV, Exp. 4, note 2) in 100 ml of THF was added, while keeping the temperature below -55°C. After an additional 15 min the cooling bath was removed, the temperature was allowed to rise to -10°C and was kept at that level for 1 h (note 1). The reddish suspension was subsequently cooled to -50°C and 0.32 mol of trimethylchlorosi1ane was added in 10 min. The cooling bath was then removed and the temperature was allowed to rise to 10°C. 

Pyran, 4-arylimino- C NMR, 3, 585 Pyran, 4-arylimino-2,6-dimethyl-synthesis, 3, 762 Pyran, 2-aryloxytetrahydro-X-ray studies, 3, 621 Pyran, 4-benzyl-isomerization, 3, 666 Pyran, 3-bromodihydro-synthesis, 3, 769 Pyran, -bromodihydro-halogen-metal exchange with t-butyllithium, 1, 474 Pyran, 2-bromotetrahydro- H NMR, 3, 579... 

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). 

OMe). The latter can be depro-= C6H40MC-P, R = H). Similar give 34 (R = NMca) and 35 (R = followed by formylferrocene and H) is formed. With -butyllithium, dilute hydrochloric acid, the sole... 

Treatment of 5//-dibenz[6,/]azepine (5, R1 = H) with an excess of butyllithium furnishes the 4,5-dilithio derivative 6, which with an equivalent of an A. A-dimethylcarboxamide undergoes regiospecific acylation at C4.206 In a similar manner, 5-acyl-5f/-dibenz[6,/]azepines, e.g. 5 (R1 = Ac), with butyllithium and carbon dioxide form dibenz[6,/]azepine-4-carboxylic acids, e.g. 7 (R1 = Ac R2 = OH).207... 

To 5.4 mmol of LDA, prepared in 25 mL of diethyl ether from diisopropylamine and 2 M butyllithium in hexane, are added 847 mg (5.00 mmol) of 2-(trimethylsilyloxy)-3-pentenenitrile in 10 mL of diethyl ether at — 78 "C. After stirring for 45 min, 671 mg (5.00 mmol) of 2-phenylpropanal, dissolved in 10 mL of diethyl ether are added. After stirring for 2 h at — 78 X, 1.20 g (10.5 mmol) of trifluoroacetie acid are added carefully to the mixture at below —70CC. 15 mL of sat. aq NH4C1 and then diethyl ether are added and the reaction mixture is allowed to reach r.t. The phases are separated and extracted with aq NH,CI and... 

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