Borane-Dimethyl sulfide-Sodium borohydride

Triethylaluminum, 204 Triisobutylaluminum, 205 Trimethylaluminum, 22, 205 Vilsmeier reagent-Lithium tri-r-butoxy-aluminum hydride, 342 Boron Compounds Alkyldimesitylboranes, 8 Allenylboronic acid, 36 9-Borabicyclo[3.3.1]nonane, 92 Borane-Dimethylamine, 42 Borane-Dimethyl sulfide-Sodium borohydride, 25... 

This procedure describes the preparation of 3-nitropropanai, 1, employing the rarely encountered 1,4-addition of ambident nitrite ion with its "softer N-atom,2 and further transformations of 1, as reported earlier.3 A similar preparation of 3-nitrobutanal from crotonaldehyde (3-butenal) is known,4 as well as analogous additions to a, 3-enones.2 The reduction of 1 to the alcohol 2, originally carried out with borane-dimethyl sulfide (BMS),3 is now more conveniently and economically done with sodium borohydride. The acetalization of 1 to yield the dimethyl acetal 3 is based on our earlier report.3... 

Any of these BH3 compounds adds readily to most alkenes at room temperature or lower temperatures. The reactions usually are carried out in ether solvents, although hydrocarbon solvents can be used with the borane-dimethyl sulfide complex. When diborane is the reagent, it can be generated either in situ or externally through the reaction of boron trifluoride with sodium borohydride ... 

SYNTHESIS A well-stirred solution of 1.77 g 2,5-dimethoxy-B-nitro-4-(n-propylthio)styrene (see under 2C-T-7 for its preparation) in 20 mL anhydrous THF was placed in an He atmosphere and treated with 1.5 mL of 10 M borane-dimethyl sulfide complex. This was followed by the addition of 0.2 g sodium borohydride, and the stirring was continued at room temperature for a week. The volatiles were removed under vacuum, and the residue was treated with 20 mL dilute HC1 and... 

In contrast to lithium aluminum hydride, sodium borohydride does not reduce amides. Another possible reagent would be DIB AH. However, in the present case four equivalents of borane-dimethyl sulfide complex was used as a 2M solution in THE The amine was obtained in 94% yield after workup with ethanol. 

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. 

Thiosaccharin is reduced by the borane-dimethyl sulfide complex to 2,3-dihydro-1,2-benz-isothiazole 1,1-dioxide <90JCR(S)106>. Sodium borohydride reduces 3-substituted 1,2-benzisothiazole... 

Organoboranes are obtained by addition of borane or alkyl boranes to alkenes (or alkynes). Borane itself can be prepared by reaction of boron trifluoride ether-ate with sodium borohydride. Borane exists as a dimer, but solutions containing an electron donor, such as an ether, amine or sulfide, allow adduct formation. The complexes BHa-THF and the borane-dimethyl sulfide complex BH3 SMc2 are commercially available and provide a convenient source of borane. The dimethyl sulfide complex is more stable than BHa-THF and has the additional advantage that it is soluble in a variety of organic solvents, such as diethyl ether and hexane. 

Herbert C. Brown, H. C. Choi, Y. M. Narasimhan, S., Addition compounds of alkah metal hydrides. 22. convenient procedures for the preparation of lithium borohydride from sodium borohydride and borane-dimethyl sulfide in simple ether solvents, Inorg. Chem. 1982, 21, 3657—3661. 

Diborane can be generated in situ from sodium borohydride and boron trifluoride. Solutions in tetrahydrofuran are commercially available. An alternative commercially available reagent is the borane-dimethyl sulfide complex ... 

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]. 

Reduction of 5,5-dimethyl-2-pyrrolidone with 3 mol of lithium aluminum hydride by refluxing for 8 hours in tetrahydrofuran gave 2,2-dimethylpyrrol-idine in 67-79% yields [1123]. Reduction of e-caprolactam was accomplished by heating with sodium bis(2-methoxyethoxy)aluminum hydride [544], by successive treatment with triethyloxonium fiuoroborate and sodium borohydride [1121], and by refluxing with borane-d ras. )a.y sulfide complex [1064]. 

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. 

Borane, which is used as a complex with tetrahydrofuran [992] or dimethyl sulfide [611, 992] or generated in situ from lithium borohydride with boron trifluoride etherate [646] or sodium borohydride with aluminum chloride [184], reacts with 3 mol of an alkene to form a tertiary borane. The oxidation with alkaline hydrogen peroxide [183, 992, 1201] or with trimethylamine oxide [991, 992] yields an alcohol (equations 598 and 599). 

Malate esters are easily reduced in a highly selective fashion using either diborane [40,41] or borane—methyl sulfide complex [42— 45] in the presence of a catalytic amount of sodium borohydride (5 mol%) to give diol esters 45. Yields of 45a and 45b generally range from 80-97%, while 45c is formed in 60% yield [46]. Dimethyl (5)-malate is reduced with 99 1 selectivity as regards C-1 to C-4 ester reduction, while diethyl ( S)-malate shows even greater selectivity (200 1). 

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