Of lithium borohydride

Replacing the metal Al by a boron atom as the metal chelate center, Tao et al. reported lithium tetra-(2-methyl-8-hydroxy-quinolinato) boron (LiB(qm)4, 240) (Scheme 3.73) quantitatively prepared by reaction of lithium borohydride (LiBH4) with four equivalents of 2-methyl-8-hydroxy-quinoline in ethanol at room temperature [266]. LiB(qm)4 is a pure blue emitter with a maximum peak emission at 470 nm with FWHM of 75 nm. Devices of... 

Borane prepared by adding aluminum chloride to a solution of sodium borohydride in diethylene glycol dimethyl ether (diglyme) reduced aliphatic and aromatic esters to alcohols in quantitative yields in 3 hours at 25° using a 100% excess, or in 1 hour at 75° using a 25% excess of lithium borohydride over 2 mol of the hydride per mol of the ester [738] Procedure 20, p. 209). 

The proposal of the ester linkage was later withdrawn when it was found that the decomposition products of lithium borohydride (presumably dimethoxyborane) in acidic anhydrous methanol can reduce free carboxyl groups (37). 

Note. (1) Reaction of lithium borohydride with water may be rapid and violent do not expose to high humidity and avoid contact with eyes, skin and clothing (contact with cellulosic material may cause combustion). It should be handled with the same caution as is afforded to lithium aluminium hydride (Section 4.2.49, p. 445). 

Preparation, The reagent is prepared by the reaction of lithium borohydride with boron trichloride (5-10% excess) in diethyl ether at 0°. The reagent can be stored for several weeks at 0-5°. 

Preparation. The reagent is prepared in ether solution by the reaction of lithium borohydride with boron trichloride. 

Fig. 9. Use of lithium borohydride to study COOH-terminal amino acids.

The enthalpy of formation of lithium borohydride crystal was calculated to be -45.522 kcal mol data ... 

The reagent is prepared by reaction of lithium borohydride with liquid hydrogen cyanide in ether and isolated as the dioxane complex. It is remarkably stable to... 

To a 0 °C solution of lithium borohydride (1.32 g, 60.54 mmol) in THF (30 mL) was added trimethylsilyl chloride (15.40 mL, 121.1 mmol). The ice-water bath was removed, and the mixture was stirred at room temperature for 15 min. The mixture was cooled to 0 °C and (5)-phenylalanine (5.00 g, 30.27 mmol) was added. The ice-water bath was removed, and the reaction mixture was stirred for 16 h. The mixture was cooled again to 0 °C and methanol (45 mL) was added dropwise followed by a sodium hydroxide solution (2.5 M, 25 mL). The organic solvents were evaporated in vacuo and the residue was extracted with CHCI3 (5 x 50 mL). The combined extracts were dried (Na2SO4), filtered, and evaporated in vacuo to leave 4.55 g (99%) of (5)-phenylalaninol as a white crystalline solid. 

A solution of the lactone (3.40 g, 13.18 mmol) in dry THF (10 mL) was added drop-wise to a solution of lithium borohydride (2 M in THF, 16 mL, 32 mmol) in THF (80 mL) at 0 °C. The mixture was stirred overnight allowing room temperature to be reached. The reaction was poured into a cold mixture of saturated ammonium chloride (300 mL) and diethyl ether (300 mL), the phases were separated, and the aqueous layer extracted with ether. The combined organic extracts were washed with water and brine, dried (magnesium sulfate), and concentrated. The residue was purified by chromatography [150 g silica gel, hexanes/EtOAc (3 1 to 3 2)] to afford 3.391 g (98%) of the diol as a colorless oil. 

M-Octylbromide and p-bromotoluene are completely inert toward 9-BBN. Although the reaction of epoxides with 9-BBN is quite sluggish and requires 3-8 days for completion, the introduction of a catalytic (7.5 mol%) of lithium borohydride converts 1,2-butylene oxide to 98% of 2-butanol (Eq. 25.6). 

W. R. Purdum and E. M. Kaiser. Tris(A-methylanilino)borane. Inorg. Synth., 1977, 17, 162. A. G. Smith and C. J. W. Brooks. Gas chromatography chemical ionization mass spectrometry of prostaglandin F cyclic boronate derivatives. Biomed. Mass Spectrometry, 1977, 4, 258. A. Uzarewicz and E. Segiet-Kujawa. Action of borane on (-l-)-2a,10-epoxypinane in the presence of lithium borohydride, Roczniki Chem., 1977, 51,2147. 

---