Lithium n-butylborohydride

Lithium n-butylborohydride, Li-rr-BuBH3. Mol. wt. 77.89. The reagent is prepared by reaction of n-butyllithium with borane-dimethyl sulfide. 

REDUCTION, REAGENTS Aluminum amalgam. Borane-Dimethyl sulfide. Borane-Tetrahydrofurane. t-Butylaminoborane. /-Butyl-9-borabicyclo[3.3.1]nonane. Cobalt boride— f-Butylamineborane. Diisobutylaluminum hydride. Diisopropylamine-Borane. Diphenylamine-Borane. Diphenyltin dihydride. NB-Enantrane. NB-Enantride. Erbium chloride. Hydrazine, lodotrimethylsilane. Lithium-Ammonia. Lithium aluminum hydride. Lithium borohydride. Lithium bronze. Lithium n-butylborohydride. Lithium 9,9-di-n-butyl-9-borabicyclo[3.3.11nonate. Lithium diisobutyl-f-butylaluminum hydride. Lithium tris[(3-ethyl-3pentylK>xy)aluminum hydride. Nickel-Graphite. Potassium tri-sec-butylborohydride. Samarium(II) iodide. Sodium-Ammonia. Sodium bis(2-mcthoxyethoxy)aluminum hydride. 

Of the large number of reducing agents, the most useful are DIB AH and lithium n-sec-butylborohydride. Regardless of the nature of R, DIB AH reduces 3 mainly to the alcohol 4 (the anti-Cram product) in 60-80% de. Reduction with L-Selectride usually proceeds in the opposite sense and in accordance with Cram s chelate rule, but high selectivity is observed only when R is a primary or tertiary alkyl group. 

REDUCTION, REAGENTS Bis(N-methylpi-perazinyl)aluminum hydride. Borane-Di-methyl sulfide. Borane-Tetrahydrofurane. Borane-Pyridine. n-Butyllithium-Diisobu-tylaluminum hydride. Calcium-Amines. Diisobutylaluminum hydride. 8-Hydroxy-quinolinedihydroboronite. Lithium aluminum hydride. Lithium 9-boratabicy-clo[3.3.1]nonane. Lithium n-butyldiisopro-pylaluminum hydride. Lithium tri-j c-butylborohydride. Lithium triethylborohy-dride. Monochloroalane. Nickel boride. 2-Phenylbenzothiazoline. Potassium 9-(2,3-dimethyl-2-butoxy)-9-boratabicy-clo[3.3.1]nonane. Raney nickel. Sodium bis(2-methoxyethoxy)aluminum hydride. Sodium borohydride. Sodium borohy-dride-Nickel chloride. Sodium borohy-dride-Praeseodymium chloride. So-dium(dimethylamino)borohydride. Sodium hydrogen telluride. Thexyl chloroborane-Dimethyl sulfide. Tri-n-butylphosphine-Diphenyl disulfide. Tri-n-butyltin hydride. Zinc-l,2-Dibromoethane. Zinc borohydride. 

Lithium /i-butylborohydride is prepared by reacting equimolar amounts of n-butyl lithium and bo-rane dimethyl sulfide complex.This reagent effectively reduces enones in toluene-hexane mixtures at -78 °C to give, in most cases, high yields of the corresponding allylic alcohols.Conjugated cyclopen-tenones, however, give mixtures of 1,2- and 1,4-reduction products. Under identical reaction conditions, saturated ketones are reduced to alcohols. The latter process can take place in the presence of simple esters. 

L-Selectride reduction of a-dibenzylamino ketones. Interestingly, a-benzyloxy ketones give anri-l,2-diol monobenzyl ethers with low isomer ratios (e.g, anti syn =6 1) which can be increased dramatically by changing the reducing agent to lithium tri-n-butylborohydride (>99 1). ... 

S,5S)-2-Methyl-4-methoxymethyl-5-phenyl-2-oxazoline. Naphthalene-Lithium. Perchloric acid. Potassium tri-n-butylborohydride. 

Enol triflatesfrom affi-enones.1 The reaction can be carried out by conjugate reduction of the enone with lithium tri-sec-butylborohydride followed by reaction of the resulting enolate with N-phenyltriflimide. The method is generally useful, but 1,2-reduction can predominate in the case of (3,(3- or even y,y-disubstituted a,(3-enones. 

SlLYL ENOL ETHERS Chiorotrimethylsilane-Zinc, 82 Lithium amides, chiral, 159 Lithium tri-sec-butylborohydride, 167 Organotin reagents, 211 Osmium tetroxide-Trimethylamine N-ox-ide-Pyridine, 223... 

Enantiomerically pure carboxylic acids are routinely obtained from N-acylsultams by Hydrogen Peroxide assisted saponification with Lithium Hydroxide in aqueous THF. 4 Alternatively, transesterification can be effected under neutral conditions in allyl alcohol containing Titanium Tetraisopropoxide, giving the corresponding allyl esters which can be isomerized/hydrolyzed with Wilkinson s catalyst (Chlorotris(triphenylphosphine)rhodium(I)) in Et0H-H20. This provides a convenient route to carboxylic acids containing base-sensitive functionality. Primary alcohols are obtained by treatment with L-Selectride (Lithium Tri-s-butylborohydride) in THF at ambient temperature. ... 

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