Tetrabutylammonium borohydrid

Tetrabutylammonium borohydride [33725-74-5] M 257.3, m 128-129 . Purified by recrystn from EtOAc followed by careful drying under vacuum at 50-60°. Samples purified in this way showed no signs of loss of active H after storage at room temperature for more than 1 year. Nevertheless samples should be stored at ca 6° in tightly stoppered bottles if kept for long periods. It is soluble in CH2CI2. [J Org Chem 41 690 1976 Tetrahedron Lett 3113 1972.]... 

In this context, tetrabutylammonium borohydride - a strong reducing agent... 

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). 

High yields (76-81%) of alcohols are also obtained by adding solutions of acyl chlorides in anhydrous dioxane or diethyl carbitol to a suspension of sodium borohydride in dioxane and brief heating of the mixtures on the steam bath [751], by stirring solutions of acyl chlorides in ether for 2-4 hours at room temperature with aluminum oxide (activity I) impregnated with a 50% aqueous solution of sodium borohydride (Alox) (yields 80-90%) [1014], by refluxing acyl chlorides with ether solutions of sodium trimethoxyborohydride [99], or by treatment of acyl chlorides in dichloromethane solutions with tetrabutylammonium borohydride at —78° [771]. A 94% yield of neopentyl alcohol was achieved by the reaction of trimethylacetyl chloride with tert-butylmagnesium chloride [324]. 

Baeckstrom and coworkers utilized the enhanced selectivity of singlet oxygen towards different types of double bonds, as the key step for the synthesis of trani-Sabinene . By using the method of simultaneous oxidation and reduction (Rose Bengal sensitized photooxidation in the presence of tetrabutylammonium borohydride) they managed to isolate compound 166 by a total conversion of 164 (Scheme 61). Compound 165 remained... 

The synthesis of 3-hydroxy-2-methyl esters and amides in a stereoselective manner is a challenge which needs to be met due to the prevalence of these moieties in natural products201. This has been accomplished by using sodium borohydride, catalyzed by manganese(II) chloride or by tetrabutylammonium borohydride (equation 52)202,203. 

PTC procedures using tetrabutylammonium borohydride have been described.47... 

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. 

Treatment of halides or sulfonates with hydride donors such as tetrabutylammonium borohydride,38 lithium aluminium hydride,39 lithium triethylborohydride46 or sodium borohydride generate deoxy sugar derivatives (Scheme 3.8c).41 When sodium borohydride is employed, a transition metal catalyst (PdCk or NiC-b) may be added. 

The reduction of tellurium and the alkylation of telluride was carried out in one step using tetrabutylammonium borohydride in refluxing toluene. Dibutyl tellurium was obtained in 95% yield. With tetraethyl-, tetrapropyl-, and tetrahexylammonium borohydride, no reaction occurred2. 

Treatment of enantiomerically pure sulfoximinooxiranes 249 with magnesium bromide in the presence of tetrabutylammonium borohydride gave the enantiomerically enriched bromohydrins 252 in good yields and with enantiomeric purities ranging from 70 to 91 %.116... 

The synthesis and chemistry of an 7] -selenophene osmium complex 50 has been studied <19990M1559>. Protonation and electrophilic substitution with acetaldehyde diethyl acetal occurred at C-2. Methylation of complex 50 with methyl triflate gave 51 which upon treatment with tetrabutylammonium borohydride (TBAB) led to the selenophene ring-opened complex 52 (Scheme 5). 

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. ... 

This last reaction is known as the homo-Diels-Alder reaction. A similar reaction has been reported with alkynes, using a mixture of a cobalt complex, Znl2 and tetrabutylammonium borohydride as catalysts. ... 

The reduction of secondary sulfonates with lithium aluminum hydride or sodium borohydride is usually a poor reaction for deoxygenating secondary alcohols [220,222], In most cases, the hydride attack will occur at sulfur and result in cleavage of the S-0 bond to afford the starting secondary alcohol as the main product. An exception from this rule is observed when tetrabutylammonium borohydride is used for reduction of secondary triflates in refluxing benzene [239]. Under these conditions clean displacement with hydride occurs to give the corresponding deoxy compounds in good yield (O Table 14). 

On the other hand, these values are dramatically modified if the presence of alkali-metal (sodium) counterions is taken into account, the ion-paired trianions becoming by far the most stable species (E = —4.5 eV). On this basis, it has been postulated that in the butoxide reduction of 65 and 67 formation of the potassium ion-paired trianions would be favored over that of the ion-paired monoanions, while reduction with tetrabutylammonium borohydride in THF or the electro-... 

Very interesting transformations of the polyketones into other polymeric materials have been reported. An optically active isotactic poly[l-oxo-2-mefhylpro-pane-l,3-diyl] was reacted with methylenation reagents to give poly[l-methylene-2-methylpropane-l,3-diyl] ]143] apparently without racemization. A similar material was reduced to the corresponding poly[l-hydroxo-2-methylpropane-l,3-diyl] with 40% 1-diastereoselectivity using tetrabutylammonium borohydride [144]. Furthermore, ethene copolymers or efhene-propene terpolymers were transformed into... 

Reductions Carbonyl compounds, including conjugated members, acid chlorides, azides, epoxides, and disulfides, are reduced. This salt (1) is a more selective reducing agent than tetrabutylammonium borohydride. 

Tetrabutylammonium borohydride [33725-74-5] M 257.3, m 128-129°. Purify it by reciystallisation from EtOAc followed by careful drying under vacuum at 50-60°. Samples purified in this way showed no signs... 

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