Borohydrides reactions with

Sodium borohydride, reaction with ketones and aldehydes,... 

Mechanisms of sodium borohydride reactions with primary, secondary, and tertiary amides have been investigated both at the B3LYP/6-31+- -G(d,p)//B3LYP/6-31G(d,p) and B3LYP/6-31++G(d,p)//HF/6-31G(d,p) levels of theory. The predicted structures of the key intermediates were then confirmed by experiment.317 For chemoselective reductions of a-substituted and aromatic esters with sodium borohydride, agreement between experimental results and theoretical computations at the B3LYP/6-31+-1-G(d,p)//HF/6-31G(d,p) levels of theory have been reported.318... 

Sodium. Slow reaction with anhydrous acid explosive reaction with aqueous acid.28 Sodium Borohydride. Reaction with concentrated sulfuric acid to yield diborane may... 

Fluoroalkjiations are frequentiy performed indirectly using tandem reactions. Arenes react with sodium borohydride in trifluoroacetic acid to afford otherwise difficult to obtain l,l,l-trifluoro-2,2-diarylethanes. Presumably sodium borohydride reacts initially with the trifluoroacetic acid to produce the trifluoroacetaldehyde or its equivalent, which rapidly undergoes Friedel-Crafts-type condensation to give an intermediate carbinol. The carbinol further alkylates ben2ene under the reaction conditions giving the observed product. The reaction with stericaHy crowded arenes such as mesitylene and durene... 

Catalytic reduction of folic acid to 5,6,7,8-tetrahydrofolic acid (225) proceeds fast in trifluoroacetic acid (66HCA875), but a modified method using chemical reductants leads with sodium dithionite to 7,8-dihydrofolic acid (224). Further treatment with sodium borohydride gives (225) which has been converted into 5-formyl-(6i ,S)-5,6,7,8-tetrahydro-L-folic acid (leucovorin) (226) by reaction with methyl formate (equation 70) (80HCA2554). 

Timko and Cram were the first to prepare true crown ethers containing the furanyl subcyclic unit ° . Destructive distillation of sucrose yielded 2-hydroxymethyl-5-formyl-furan 7 in 41% yield. This could be reduced to the corresponding diol in 91% yield by treatment with sodium borohydride. Reaction of the diol with tetraethylene glycol dito-sylate, and potassium t-butoxide in THE solution afforded the crown in 36% yield. The approach is illustrated below as Eq. (3.26). 

The azidohydrins obtained by azide ion opening of epoxides, except for those possessing a tertiary hydroxy group, can be readily converted to azido mesylates on treatment with pyridine/methanesulfonyl chloride. Reduction and subsequent aziridine formation results upon reaction with hydrazine/ Raney nickel, lithium aluminum hydride, or sodium borohydride/cobalt(II)... 

With Af-acyl or Af-sulfonyl hydrazines as nucleophiles, Zincke salts serve as sources of iminopyridinium ylides and ylide precursors.Reaction of the nicotinamide-derived Zincke salt 8 with ethyl hydrazino urethane 42 provided salt 43, while the tosyl hydrazine gave ylide 44 (Scheme 8.4.14). ° Benzoyl hydrazines have also been used in reactions with Zincke salts under similar conditions.Af-amino-1,2,3,6-tetrahydropyridine derivatives such as 47 (Scheme 8.4.15), which showed antiinflammatory activity, are also accessible via this route, with borohydride reduction of the initially formed ylide 46. ... 

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