Sodium borohydride-boron trifluoride

Reduction to the corresponding ] -substituted pyrrolidine (23) (lakes place with sodium borohydride/boron trifluoride. Saponification completes the synthesis of the diuretic agent piret-.inide (24). ... 

Although the synthesis of multiple-pyrrolyl compounds can be achieved by SnAt reactions of perfluoroaromatics with pyrrolylsodium at ambient temperature <96JOC9012>, deleterious side reactions are often observed during attempted A-alkylations of the alkali salts of pyrrole. A protocol has therefore been developed for the preparation of N-arylmethylenepyrroles by reduction of the corresponding AT-acyl derivatives by treatment with sodium borohydride/boron trifluoride etherate in a sealed tube <96S457>. ... 

Sodium borohydride-Ace tic acid, 278 Sodium borohydride-Boron trifluoride etherate, 42... 

Chlorosulfonic acid Thionyl chloride Sodium borohydride Boron trifluoride etherate Maleic acid Carbon (Darco KB)... 

Carboxylic Adds and Derivatives.—Esters may be reduced to ethers in low yield by lithium aluminium hydride-aluminium chloride.This reaction would not normally be used for preparative purposes, being more effectively carried out with sodium borohydride-boron trifluoride, but could complicate the use of LiAlH4-AICI3 for other purposes such as the reductive cleavage of the spiroacetal system in sapogenins. 

The pyridazinc moiety of ethyl l-ethyl-6-fluoro-4-oxo-7-(4-tolylsulfanyl)-l,4-dihydropyri-do[2,3-c]pyridazine-3-carboxylate can be reduced by the sodium borohydride/boron trifluoride-diethyl ether complex to give ethyl l-ethyl-6-fluoro-7-(4-tolylsulfanyl)-l,4-dihydropyrido [2,3-c]pyridazine-3-carboxylate.9... 

Attempts to convert the sulfones back into PASHs have been successful with a number of agents such as various metals (zinc, tin, magnesium, aluminum, iron, and nickel) in acetic acid, palladium on carbon with hydrazine, stannous chloride, lithium triethylborohydride, diphenylsi-lane, sodium borohydride, boron trifluoride, dicyclohexylcarbodiimide, triethyl phosphite, dimethyl dichlorosUane with lithium aluminum hydride, diphenylsilane, and triphenyl phosphine with iodine. However, none of them cleanly effect this conversion. 

The reverse selectivity has been described with diborane/boron trifluoride, sodium borohydride/dibo-rane, 2 sodium borohydride/trichlorotrispyridine-rhodium, lithium 9,9-di-/i-butyl-9-borabicyclo-[3.3.1]nonanate (for structure, see Table 4), sodium cyanoborohydride/boron trifluoride, and... 

A 500-ml three-necked flask is fitted with a dropping funnel, a condenser, and a magnetic stirrer. The flask is charged with a mixture of 3.4 g (0.09 mole) of powdered sodium borohydride, 150 ml of THF, and 25.2 g (0.30 mole) of 4-methyI-I-pentene. A solution of 15.1 ml (17.0 g, 0.12 mole) of boron trifluoride etherate in 20 ml of THF is added over a period of 1 hour, the temperature being maintained at 25° (water bath). The flask is stirred an additional hour at 25° and the excess hydride is decomposed with water (10 ml). 

The sodium borohydride solution is added dropwise to the stirred boron trifluoride etherate-diglyme solution resulting in the formation of diborane. The gas is swept into the olefin-TH F solution (held at 20°) by maintaining a slow flow of dry nitrogen through the generator. 

A 500-ml flask is equipped with a thermometer, a magnetic stirrer, and a dropping funnel, and all openings are protected by drying tubes. The system is flushed with nitrogen and a solution of 2.84 g (0.075 mole) of sodium borohydride in 150 ml of diglyme is introduced followed by 28.3 g (0.30 mole) of norbornene. The flask is immersed in an ice-water bath and the hydroboration is achieved by the dropwise addition of 27.4 ml (0.10 mole) of boron trifluoride diglymate. The solution is stirred... 

H.12 The reaction of boron trifluoride, BF,(g), with sodium borohydride, NaBH4(s), leads to the formation of sodium tetrafluoroborate, NaBF4(s), and diborane gas, B2Hfc(g). The diborane reacts with the oxygen in air, forming boron oxide, B20 j(s), and water. Write the two balanced equations leading to the formation of boron oxide. 

The boranes are an extensive series of binary compounds of boron and hydrogen, somewhat analogous to the hydrocarbons. The starting point for borane production is the reaction (in an organic solvent) of sodium borohydride with boron trifluoride ... 

An alternative diborane source was used by the checker. Diborane was generated by adding boron trifluoride-ethyl ether to sodium tetrahydroborate (sodium borohydride) in ether. The generator was charged to yield a maximum of 0.6 mol of... 

A boron analog - sodium borohydride - was prepared by reaction of sodium hydride with trimethyl borate [84 or with sodium fluoroborate and hydrogen [55], and gives, on treatment with boron trifluoride or aluminum chloride, borane (diborane) [86. Borane is a strong Lewis acid and forms complexes with many Lewis bases. Some of them, such as complexes with dimethyl sulfide, trimethyl amine and others, are sufficiently stable to have been made commercially available. Some others should be handled with precautions. A spontaneous explosion of a molar solution of borane in tetrahydrofuran stored at less than 15° out of direct sunlight has been reported [87]. 

For the reduction of aliphatic ketones to hydrocarbons several methods are available reduction with triethylsilane and boron trifluoride [772], Clemmensen reduction [160, 758] (p. 28), Wolff-Kizhner reduction [280, 281, 759] (p. 34), reduction of p-toluenesulfonylhydrazones with sodium borohydride [785], sodium cyanoborohydride [57i] or borane [786] (p. 134), desulfurization of dithioketals (jaeicaipioles) [799,823] (pp. 130,131) and electroreduction [824]. 

Sodium borohydride does not reduce the free carboxylic group, but borane prepared from sodium borohydride and boron trifluoride etherate in tetrahydrofuran converts aliphatic acids to alcohols at 0-25° in 89-100% yields... 

Reduction of aromatic carboxylic acids to alcohols can be achieved by hydrides and complex hydrides, e.g. lithium aluminum hydride 968], sodium aluminum hydride [55] and sodium bis 2-methoxyethoxy)aluminum hydride [544, 969, 970], and with borane (diborane) [976] prepared from sodium borohydride and boron trifluoride etherate [971, 977] or aluminum chloride [755, 975] in diglyme. Sodium borohydride alone does not reduce free carboxylic acids. Anthranilic acid was reduced to the corresponding alcohol by electroreduction in sulfuric acid at 20-30° in 69-78% yield [979],... 

Diborane is prepared by the reaction of sodium borohydride with iodine or boron trifluoride or trichloride in diglyme ... 

Volatile boron compounds, especially boranes, are usually more toxic than boric acid or soluble borates (Table 29.9) (NAS 1980). However, there is little commercial production of synthetic boranes, except for sodium borohydride — one of the least toxic boranes (Sprague 1972). Boron trifluoride is a gas used as a catalyst in several industrial systems, but on exposure to moisture in air, it reacts to form a stable dihydride (Rusch etal. 1986). Eor boric oxide dusts, occupational exposures to 4.1 mg/m (range 1.2 to 8.5) are associated with eye irritation dryness of mouth, nose and throat sore throat and cough (Garabrant et al. 1984). 

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