With sodium borohydride

Piette, D. Debergh, M. Baiwir, G. Llabres, Spectrochim. Acta, Part A 36, 769 (1980). 

The reduction of diorgano ditellurium compounds by sodium borohydride is applicable to both dialkyl, divinyl and diaryl ditellurium compounds (Table 2 p. 166). 

Sodium Butanetellurolate 7.4 g (20 mmol) of dibutyl ditcllurium are dissolved in a mixture of 50 m/ of methanol and 50 ml of tetrahydrofuran and placed in a nitrogen-flushed, three-necked, 250 ml flask fitted with a reflux condenser, stirrer, and dropping funnel. The mixture is heated to reflux on a water bath and a solution of 1.2 g (10.03 mmol) of sodium borohydride in 30 ml of 1 molar aqueous sodium hydroxide solution is added until the solution becomes colorless. 

Sodium Octanetellurolate 0.63 g (1.3 mmol) of dioctyl ditellurium are dissolved in a mixture of 20 ml of ethanol and 20 ml of benzene. The solution is placed in a nitrogen-flushed, 100 ml flask fitted with a magnetic stirrer and a nitrogen inlet. Solid sodium borohydride is added in small portions to the stirred solution until the red color disappears. 

The reduction of ditellurium compounds with sodium borohydride is suitable for the generation of sodium tellurolates derived from carbohydrates.  

The alkene function of 4-[(2-nitrophenyl)methylidene]pyrazol-3-ones 558a-c was 

Compounds 566d i exhibited significant anti-bacterial action against Escherichia coli K12.J5, Salmonella panama Nr.7.3 and Staphylococcus aureus 209P strains. 

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In this preparation, phenyi-2-nitropropene is reduced to phenyl-2-nitropropane with sodium borohydride in methanol, followed by hydrolysis of the nitro group with hydrogen peroxide and potassium carbonate, a variety of the Nef reaction. The preparation is a one-pot synthesis, without isolation of the intermediate. 

Reduction to alcohols (Section 15 2) Aide hydes are reduced to primary alcohols and ketones are reduced to secondary alcohols by a variety of reducing agents Catalytic hydrogenation over a metal catalyst and reduction with sodium borohydride or lithium aluminum hydride are general methods... 

The enzyme is a single enantiomer of a chiral molecule and binds the coenzyme and substrate m such a way that hydride is transferred exclusively to the face of the carbonyl group that leads to (5) (+) lactic acid Reduction of pyruvic acid m the absence of an enzyme however say with sodium borohydride also gives lactic acid but as a racemic mixture containing equal quantities of the R and S enantiomers... 

The structure of the bicychc monoterpene borneol is shown in Figure 26 7 Isoborneol a stereoisomer of borneol can be prepared in the labora tory by a two step sequence In the first step borneol is oxidized to camphor by treatment with chromic acid In the second step camphor is reduced with sodium borohydride to a mixture of 85% isoborneol and 15% borneol On the basis of these transformations deduce structural formulas for isoborneol and camphor... 

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... 

Lynestrenol is the des-3-oxo derivative of norethindrone (28). It has been prepared through a similar synthetic pathway as aHylestrenol (37) (52), ie, addition of potassium acetyUde, rather than aHyl magnesium bromide, affords lynestrenol (73). Lynestrenol is also available from norethindrone (28). Reduction of the 3-keto group is accompHshed by treating norethindrone (28) with sodium borohydride in the presence of trifluoro- or trichloroacetic acid... 

Unusual reducing properties can be obtained with borohydride derivatives formed in situ. A variety of reductions have been reported, including hydrogenolysis of carbonyls and alkylation of amines with sodium borohydride in carboxyHc acids such as acetic and trifluoroacetic (38), in which the acyloxyborohydride is the reducing agent. 

When an aqueous effluent stream containing organomercurials cannot be recycled, it may be treated with chlorine to convert the organomercury to inorganic mercury. The inorganic compounds thus formed are reduced to metallic mercury with sodium borohydride. The mercury metal is drained from the reactor, and the aqueous solution discarded. The process utilising sodium borohydride is known as the Ventron process (27). 

Higher nitroalkanes are prepared from lower primary nitroalkanes by a one-pot synthesis (69). Successive condensations with aldehydes and acylating agents are followed by reduction with sodium borohydride. Overall conversions in the 75—80% range are reported. 

The relationships among the various streptovaricins were shown by the following reactions streptovaricin E (8) converts to streptovaricin C (6) upon treatment with sodium borohydride streptovaricins A (4), G (9), and K (11) yield the same triacetate derivative upon acetylation streptovaricins B (5), C (6), and J (10) yield the same tri- and tetraacetate derivatives upon acetylation streptovaricin G (9) converts to streptovaricin (12) upon treatment with base (4). The open-chain streptovaricin U (13) has also been isolated from the streptovaricin complex (5). 

Isoquinoline also forms Reissert compounds when treated with benzoyl chloride and alkyl cyanide (28), especially under phase-transfer conditions (29). The W-phenylsulfonyl Reissert has been converted to 1-cyanoisoquinoline with sodium borohydride under mild conditions (154). When the AJ-benzoyl-l-alkyl derivative is used, reductive fission occurs and the 1-alkyLisoquinoline is obtained. 

Morpholiaoglucopyranosides have beea syathesized from sucrose by selective lead tetraacetate oxidatioa of the fmctofuranosyl ring to a dialdehyde (6). This product was subjected to reductive amination with sodium borohydride and a primary amine such as benzylamine to produce the /V-henzy1morpho1ino derivative (7) (99). 

Another viable method for the synthesis of L-foUc acid (1) starts from 6-formylpterin (23). The diester of L-glutamic acid (24) is condensed with 6-formylpterin (23). Reduction of the Schiff base with sodium borohydride is followed by hydrolysis to yield L-foUc acid (37). 

Pyridoxal Derivatives. Various aldehydes of pyridoxal (Table 3) react with hemoglobin at sites that can be somewhat controlled by the state of oxygenation (36,59). It is thereby possible to achieve derivatives having a wide range of functional properties. The reaction, shown for PLP in Figure 3, involves first the formation of a Schiff s base between the amino groups of hemoglobin and the aldehyde(s) of the pyridoxal compound, followed by reduction of the Schiff s base with sodium borohydride, to yield a covalendy-linked pyridoxyl derivative in the form of a secondary amine. 

Synthesis. The parent compound, bora2iae [6569-51-3] is best prepared by a two-step process involving formation of B-trichlorobora2iQe followed by reduction with sodium borohydride. These reactions have been studied ia some detail (96). 

Carbonyl-containing and unsaturated materials are removed by treatment with sodium borohydride (227,228) and boric acid (229). Other methods used to remove carbonyl impurities include treatment with hydroxyl amine hydrochloride, potassium permanganate, or A/-hydroxyben2enesulfonamide (229). 

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). 

Cationic rings are readily reduced by complex hydrides under relatively mild conditions. Thus isoxazolium salts with sodium borohydride give the 2,5-dihydro derivatives (217) in ethanol, but yield the 2,3-dihydro compound (218) in MeCN/H20 (74CPB70). Pyrazolyl anions are reduced by borohydride to pyrazolines and pyrazolidines. Thiazolyl ions are reduced to 1,2-dihydrothiazoles by lithium aluminum hydride and to tetrahydrothiazoles by sodium borohydride. The tetrahydro compound is probably formed via (219), which results from proton addition to the dihydro derivative (220) containing an enamine function. 1,3-Dithiolylium salts easily add hydride ion from sodium borohydride (Scheme 20) (80AHC(27)151). 

A complex of 9-BBN with MMA can be formed and compounded with sodium borohydride [92], Derivatives from the combination of 9-BBN with fatty acid or fatty alcohol give an initiator with improved stability [93], Stability appears to improve with increasing molecular weight, so oligomeric and polymeric analogs... 

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). 

A. Reductions with Sodium Borohydride Without Protecting Groups... 

Refluxing 3a-hydroxy-5)5-pregnane-ll,20-dione in methanol overnight with sodium borohydride gives the 3a,llj5,20jS-triol in 85% yield with mp 233-235°, [ ][) 38.9° (dioxane). 

When 3a,17a-dihydroxy-5jS-pregnane-ll,20-dione is allowed to react at room temperature overnight with sodium borohydride in aqueous methanol, no crystals form and only 5j5-pregnane-3a,l ljS,17a,20j5-tetrol is isolated in good yield. If the reaction is halted at the end of 3 h y the addition of water and extraction with chloroform, it is possible xo obtain a 55% yield of 3a,17a,20jS-trihydroxy-5j5-pregnan-ll-one, mp 218-220°,after recrystallization of the chloroform residue from aqueous methanol. The analytical sample, crystallized once more, has mp 219.0-220.6° [a][, 36° (acetone), reported mp 220° [aJu 38°. 

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