Borohydride, sodium reaction 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... 

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). 

Two years later, the same group reported a formal synthesis of ellipticine (228) using 6-benzyl-6H-pyrido[4,3-f>]carbazole-5,ll-quinone (6-benzylellipticine quinone) (1241) as intermediate (716). The optimized conditions, reaction of 1.2 equivalents of 3-bromo-4-lithiopyridine (1238) with M-benzylindole-2,3-dicarboxylic anhydride (852) at —96°C, led regioselectively to the 2-acylindole-3-carboxylic acid 1233 in 42% yield. Compound 1233 was converted to the corresponding amide 1239 by treatment with oxalyl chloride, followed by diethylamine. The ketone 1239 was reduced to the corresponding alcohol 1240 by reaction with sodium borohydride. Reaction of the alcohol 1240 with f-butyllithium led to the desired 6-benzylellipticine quinone (1241), along with a debrominated alcohol 1242, in 40% and 19% yield, respectively. 6-Benzylellipticine quinone (1241) was transformed to 6-benzylellipticine (1243) in 38% yield by treatment with methyllithium, then hydroiodic acid, followed... 

The benzotriazole moiety of iV-(a-aminoalkyl)benzotriazoles is readily replaced by hydride upon reduction with sodium borohydride, or with a carbanion by reaction with Grignard or lithium reagents. These are two most important reactions of benzotriazole derivatives from which versatile routes have been developed for the synthesis of primary, secondary, and tertiary amines. 

When o bonds act as nucleophiles, the electrons also have to go to one end of the c bond as they form a new bond to the electrophile. We can return to an earlier example, the reaction of sodium borohydride (NaBH4) with a carbonyl compound, and complete the mechanism. In this example, one of the atoms (the hydrogen atom) moves away from the rest of the BH4 anion and becomes bonded to the carbonyl compound. 

Sodium borohydride is one of the weakest hydride donors available. The feet that it can be used in water is evidence of this as more powerful hydride donors such as lithium aluminium hydride, LiAlI-fe, react violently with water. Sodium borohydride reacts with both aldehydes and ketones, though the reaction with ketones is slower for example, benzaldehyde is reduced about 400 times faster than acetophenone in isopropanol. 

Oxoselenazoline-4(7 )-carboxylic acid 89 and 2(iJ,6)-methylselenazolidine-4(/J)-carboxylic acid 90 were prepared from selenocysteine. Selenocysteine is prepared by reduction of selenocystine using sodium borohydride. Reaction of selenocysteine with l,T-carbonyldiimidazole affords 2-oxoselenazoline-4(R)-carboxylic acid 89 and reaction with acetaldehyde gives 2(R,6)-methylselenazolidine-4(R)-carboxylic acid 90 (Scheme 21) <2001BML2911>. 

Prelab Exercise Calculate the volume of hydrogen gas generated when 3 mL of 1 M sodium borohydride reacts with concentrated hydrochloric acid. Write a balanced equation for the reaction of sodium borohydride with platinum chloride. Calculate the volume of hydrogen that can be liberated by reacting 1 g of zinc with acid. 

In two separate routes the aminoepoxides were obtained by highly stereoselective methods. Chlorination of iV -benzoylquinotoxine (5) with iV -chlorodiisopropylamine in 100% phosphoric acid in the dark gave an amorphous mixture of the epimeric a-chloroketones 85 and 86 (Scheme 8) [10). Reduction with sodium borohydride or with lithium tri-i-butoxyaluminum hydride afforded stereoselectively a mixture of the threo chlorohydrins 87 and 88. Treatment of 87 and 88 with aqueous potassium hydroxide at 20°C gave smoothly a mixture of the erythro iV-benzoylepoxides 89 and 90. The benzoyl groups were removed reductively with diisobutylaluminum hydride to give the aminoepoxides 81 and 82 which were cyclized in refluxing toluene-methanol (100 1). This reaction yielded 9-ep -quinine (12) and 9-epi-quinidine (13) in a ratio of 2 1. The overall yield of 12 and 13 from 87 and 88 was 50%. Only traces of the erythro products quinine and quinidine were observed. 

Diselenanes (27) are available through the reactions of 1,3-propanediselenols with aldehydes and ketones in the presence of a Lewis acid such as zinc(II) chloride (Equation (3)) <85T4793, 93TL8517>. The diselenols are normally synthesized from the corresponding diselenocyanates by reduction with, for example, sodium borohydride, or with sodium in liquid ammonia <71BSB639>. 

BIS(lert-BUTYL)CHROMATE (1189-85-1) A strong oxidizer. Violent reaction with reducing agents, alcohols, combustible materials, ethers, fluorine, hydrazine, powdered metals including aluminum, magnesium, zirconium, potassium iodide, sodium tetraborate, sodium tetraborate decahydrate, sodium borohydride. Incompatible with water, steam. 

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