Sodium borohydride effect

Reduction of halides and sulfonates.2 Sodium borohydride effects this reaction under phase-transfer conditions (aqueous C6H5CH3 or CH2C12). The more lipophilic salts hexadecyltributylphosphonium bromide or tetraoctylammonium bromide are the most effective catalysts. 

Reduction of the imine with sodium borohydride leads to an intermediate amino-ester that cyclizes spontaneously to the <5-lactam function. Solvolysis of the acetyl group with methoxide followed by acylation of the hydroxyl group thus liberated with trimethoxybenzoyl chloride leads to 38. Bischler-Napieralski cyclodehydration (phosphorus oxychloride) effects closure of the remaining ring. Reduction of the imine thus formed with sodium borohydride gives 39. This, it should be noted, leads to the... 

Manx- different reducing agents are effective, but the most common choice in the laboratory is sodium cyanoborohydride, NaBH3CN. Sodium cyanoboro-hydride is similar in reactivity to sodium borohydride (NaBH4) but is more stable in weak acid solution. 

Decarboxylation of 16 using the previously described NMP, lithium chloride method provided the dione 32. Selective reduction of the least hindered carbonyl was readily effected using sodium borohydride providing 33. Hydroxymethylenation followed by O-alkylation of the butenolide unit by standard procedures provided the A-B-D-ring analog 34a,b (racemic mixture of epimers). 

Sodium hydrogen telluride, (NaTeH), prepared in situ from the reaction of tellurium powder with an aqueous ethanol solution of sodium borohydride, is an effective reducing reagent for many functionalities, such as azide, sulfoxide, disulfide, activated C=C bonds, nitroxide, and so forth. Water is a convenient solvent for these transformations.28 A variety of functional groups including aldehydes, ketones, olefins, nitroxides, and azides are also reduced by sodium hypophosphite buffer solution.29... 

Oxidation of oxyberberine (58) with lead tetraacetate effected 13-acetoxyl-ation to give 13-acetoxyoxyberberine (116), which was further oxidized to the 14-alkoxy-8,13-dioxo compounds 117 and 118 (Scheme 25). Reduction of 116 with lithium aluminum hydride followed by sodium borohydride afforded ( )-ophiocarpine (92) (78). 

Nitromethylation of aldehydes has been carried out in a one pot procedure consisting of the Henry reaction, acetylation, and reduction with sodium borohydride, which provides a good method for the preparation of l-nitroalkanes.16b 79 It has been improved by several modifications. The initial condensation reaction is accelerated by use of KF and 18-crown-6 in isopropanol. Acetylation is effected with acetic anhydride at 25 °C and 4-dimethylaminopyridine (DMAP) as a catalyst. These mild conditions are compatible with various functional groups which are often... 

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