Alcohols butyllithium

Propargylic alcohols. Butyllithium serves as a base and a nucleophile in the three-component reaction, also involving a terminal acetylene and an 7Y,A(-disubsti-tuted amide. 

Butyllithium in a mixture of hexane and diethyl ether or THE can presumably also be used for the dilithiation of propargyl alcohol. 

The ring opening of 3-substituted isoxazoles proceeds differently, and the reaction can take various courses depending on the nature of the substituent. The reaction has been effected by sodium hydroxide and sodium ethoxide in alcoholic or aqueous media and by sodium amide and also n-butyllithium in inert solvents. 

Acetylenic alcohols can be obtained using another technique from bromacety-lene with subsequent action of butyllithium and carbonyl compound (Scheme 63). 

In addition to the boron trifluoride-diethyl ether complex, chlorotrimcthylsilanc also shows a rate accelerating effect on cuprate addition reactions this effect emerges only if tetrahydrofuran is used as the reaction solvent. No significant difference in rate and diastereoselectivity is observed in diethyl ether as reaction solvent when addition of the cuprate, prepared from butyllithium and copper(I) bromide-dimethylsulfide complex, is performed in the presence or absence of chlorotrimethylsilane17. If, however, the reaction is performed in tetrahydrofuran, the reaction rate is accelerated in the presence of chlorotrimethylsilane and the diastereofacial selectivity increases to a ratio of 88 12 17. In contrast to the reaction in diethyl ether, the O-silylated product is predominantly formed in tetrahydrofuran. The alcohol product is only formed to a low extent and showed a diastereomeric ratio of 55 45, which is similar to the result obtained in the absence of chlorotrimethylsilane. This discrepancy indicates that the selective pathway leading to the O-silylated product is totally different and several times faster than the unselective pathway" which leads to the unsilylated alcohol adduct. A slight further increase in the Cram selectivity was achieved when 18-crown-6 was used in order to increase the steric bulk of the reagent. 

The synthesis of enantiomerically pure propargylic alcohols is possible using the same methodology 43b. Thus, addition of (—)-[(l-chloro-2-phenylethyl)sulfinyl]-4-methylbenzene (14) to propan-al led to a mixture of the diastereomers 15A/15B (d.r. 44 56) which are easily separated by column chromatography. After thermal elimination of the sulfinyl group the vinyl chlorides 16A/16B were obtained as a mixture of E- and Z-oleftns. Elimination of hydrogen chloride was carried out with three equivalents of butyllithium, leading to enantiomerically pure 1 -phenyl-1-pentyn-3-ol. 

Several reviews cover hetero-substituted allyllic anion reagents48-56. For the preparation of allylic anions, stabilized by M-substituents, potassium tm-butoxide57 in THF is recommended, since the liberated alcohol does not interfere with many metal exchange reagents. For the preparation of allylic anions from functionalized olefins of medium acidity (pKa 20-35) lithium diisopropylamide, dicyclohexylamide or bis(trimethylsilyl)amide applied in THF or diethyl ether are the standard bases with which to begin. Butyllithium may be applied advantageously after addition of one mole equivalent of TMEDA or 1,2-dimethoxyethane for activation when the functional groups permit it, and when the presence of secondary amines should be avoided. 

Z)-2-Butenylpotassium is generated from 4.5 mL (50 mmol) of (Z)-2-butene, 2.8 g (25 mmol) or /-BuOK. and 10.8 mL (25 mmol) oT 2.3 M butyllithium in THF for 15 min at —45 JC. This solution is cooled to — 78 C and 30 mmol of a 1 M solution of methoxy(diisopinocampheyl)borane in diethyl elher is added dropwise. The mixture is stirred for 30 min at — 78 °C, then is treated with 4mL (33 mmol) of boron trifluoride-diethyl ctherate complex this removes methoxide from the intermediate ate complex. This solution is immediatelv treated with 35 mmol of an afdchyde. Isolated yields of homoallylic alcohols are 63-79%. 

The addition of a cyclic vinyl sulfoxide anion to aldehydes has been reported only once14. Interestingly, 2,3,4,5-tetrahydro-l//-thiepane S-oxide cannot be metalated by lithium diiso-propylamide in tetrahydrofuran at — 78 °C. At higher temperatures ( — 20° to 0°) a white polymeric precipitate is formed. This polymeric product is also formed when the sulfoxide is treated with butyllithium or. wr-butyllithium in tetrahydrofuran even at — 78 C. However, metalation can be accomplished with. sec-butyllithium using an excess of N,N,N, N -tetramcthylethylenediamine in tetrahydrofuran at —78 C. In this case, a pale yellow solution is formed immediately and upon addition of benzaldehydc instantaneous dccolorization occurs yielding a mixture of diastereomeric alcohols in 90% yield. 

Sulfinyl oxiranes 2 can be desulfurized with butyllithium at very low temperature to give oxiranes with retention of configuration as a result of a ligand exchange at sulfur (see also Table 6). However, with a benzylic substituent R1, an excess of butyllithium may at higher temperatures induce an elimination to an allylic alcohol. 

The details of the mechanism are poorly understood, though the oxygen of the alcohol is certainly attacking the carbon of the isocyanate. Hydrogen bonding complicates the kinetic picture. The addition of ROH to isocyanates can also be catalyzed by metallic compounds, by light, or, for tertiary ROH, by lithium alkoxides ° or n-butyllithium. ° ... 

An experimentally simple procedure for stereoselectively preparing P-nitro alcohols has been developed. The alkyl nitronates, formed by the action of n-butyllithium on nitroalkanes in THF solution, react with aldehydes in the presence of isopropoxytitanium trichloride at room temperature to give the P-nitro alcohols enriched in the anri-diastereoisomers (Eq. 3.71).112... 

Preliminary investigations into the generality of this synthesis of lactate-derived ketones using other alkyl lithium reagents including butyllithium and phenyllithium have not been as successful. Product mixtures were typically contaminated with significant amounts of both the tertiary alcohol and the starting ester. 

Lithium ethoxide Ethyl alcohol, lithium salt (8) Ethanol, lithium salt (9) (2388-07-0) sec-Butyllithium Lithium, sec-butyl- (8) Lithium, (1-methylpropyl)- (9) (598-30-1) Acetyl chloride (8,9) (75-36-5)... 

Since cumulenes and alkynes are often easily interconvertible, many syntheses discussed above have allenic counterparts, especially base-catalyzed cyclizations of allenic alcohols.77 And, of course, several of the alkyne-based syntheses may well have allenic intermediates. There are, however, a few syntheses based specifically upon allene chemistry. In an important one, due to Stirling and his collaborators,78 an allenic sulfonium salt reacts with an enolate anion. Scheme 12 sketches the main features yields as high as 86% are recorded. Methoxyallene is easily metallated by butyllithium and so converted into an allenic epoxide that can be isomerized by fe/T-butoxide into a furan (Scheme 13) or an exocyclic equivalent similar to 15 clearly this method is particularly suited to the preparation of 3-methoxyfuran... 

Tetrahydrofurans.s The (tributylstannyl)methyl ethers (1) of homoallylic alcohols (9, 475) on treatment with butyllithium undergo tin-lithium exchange to a-... 

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