Tetrabutylammonium borohydride preparation

Complex aluminum and boron hydrides can contain other cations. The following compounds are prepared by metathetical reactions of lithium aluminum hydride or sodium borohydride with the appropriate salts of other metals sodium aluminum hydride [55], magnesium aluminum hydride [59], lithium borohydride [90], potassium borohydride [9i], calcium borohydride [92] and tetrabutylammonium borohydride [95]. 

Transformation of ketones to alcohols has been accomplished by many hydrides and complex hydrides by lithium aluminum hydride [55], by magnesium aluminum hydride [89], by lithium tris tert-butoxy)aluminum hydride [575], by dichloroalane prepared from lithium aluminum hydride and aluminum chloride [816], by lithium borohydride [750], by lithium triethylboro-hydride [100], by sodium borohydride [751,817], by sodium trimethoxyborohy-dride [99], by tetrabutylammonium borohydride [771] and cyanoborohydride [757], by chiral diisopinocampheylborane (yields 72-78%, optical purity 13-37%) [575], by dibutyl- and diphenylstannane [114], tributylstanrume [756] and others Procedure 21, p. 209). 

The allyl glycoside of a-D-Abe-(l ->3)-a-D-Man 115 was prepared by a different approach.200 The ethyl 1-thio-D-abequopyranoside donor 113 was obtained from methyl (3-D-galactopyranoside derivative 110 according to Scheme 33. The cyclic sulfate intermediate 111 was the precursor for the stereoselective reduction with tetrabutylammonium borohydride to 112 which was further derivatized to the thioglycosyl donor 113. Donor 113 was reacted with acceptor 114 to give 115 after deprotection. 

Radical anions can be prepared from phenazines using zinc(II)/potassium hydroxide in dimethyl sulfoxide as the electron source. Phenazine has a relatively high reduction potential and reacts spontaneously with tetrabutylammonium borohydride in benzene or tetrahydrofuran to give the corresponding radical anion. ... 

The reducing power of tetralkylammonium borohydrides in dichloromethane is similar to that observed in water or alcohol. A convenient preparation of tetrabutyl-ammonium borohydride has recently been reported [11] and the utility of the reagent has been surveyed [12]. In dichloromethane solution, tetrabutylammonium borohydride readily reduces aldehydes, ketones and acid chlorides while reacting only very slowly with esters (see Table 12.2). 

Deoxy-l-fluoro-L-glycerol (18) has been prepared by, among other methods, the treatment of 3,4-0-benzylidene-2,5-0-methylene-l,6-di-O-p-tolylsulfonyl-D-mannitol107 (17) with tetrabutylammonium fluoride in acetonitrile, followed by removal of the benzylidene group, periodate oxidation, reduction with borohydride, and hydrolysis. 1,6-Dideoxy-l,6-difluorogalactitol108 was obtained by treatment of 2,3 4,5-di-0-isopropylidene-l,6-di-0-(methylsulfonyl)galactitol with tetra-... 

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