Reduction by NaBH

The FOZ 310, derived from the corresponding hydrocarbon bearing a C=C link, is unusually stable (m.p. 159-161 °C) and resistant to reduction by NaBH/. Its structure was elucidated by XRD analysis, showing the same Oe envelope conformation of 288,... 

Activation of carboxylic acid. This reagent derivatizes carboxylic acids into carboxyphosphonium salts which are susceptible to reduction by NaBH to give alcohols (11 examples, 80-99%). 

Meldrum s acid the acyl group originating from the a-amino acid residue is conveniently removed (via 1,2-reduction, dehydration, and 1,4-reduction) by NaBH -HOAc without affecting the adjacent stereocenter. The products are readily converted to y-amino acids. 

B-indolylethyl bromide and debenzylated to the tertiary base (180) Cyclization by Trost s method and reduction by NaBH finally gave... 

Figure 1. Thin layer chromatograms of diesel particle extracts viewed under UV light with a fluorescent background (Left) or after reduction by NaBH /CuCl2 reagent (Right). The same samples are shown on both plates, beginning from the left a reference compound mixture of 1-nitropyrene and the three dinitro-pyrenes which ascend in the order indicated and particle extracts 1, 2, and 3 (250pg each). Samples were applied to the silica gel plates in the preabsorbant region on the bottom 3 cm of the plate.

A particularly useful reaction has been the selective 1,2-reduction of a, P-unsaturated carbonyl compounds to aHyUc alcohols, accompHshed by NaBH ia the presence of lanthanide haUdes, especially cerium chloride. Initially appHed to ketones (33), it has been broadened to aldehydes (34) and acid chlorides (35). NaBH by itself gives mixtures of the saturated and unsaturated alcohols. 

To investigate this further, we probed the state of Pt before CdS incorporation into the film. After Pt incorporation and reduction with NaBH, the Pt(4f) BE was 71.1 eV, Indicating that Pt2+ complexes were completely reduced to Pt°. Pt in films without CdS can be oxidized by boiling in nitric acid as indicated by the films becoming clear. Thus, the oxidized Pt species present in fresh CdS/Pt/Nafion films is formed at some point during the CdS incorporation process. Thus, while not excluding the process proposed by Aspnes and Heller W, we consider the reduction of partially oxidized Pt as responsible, in part, for the observed induction period (10). 

Reduced galacturonic acid and oligogalacturonides (GalU-oI, diGalU-ol, triGalU-ol and pentaGalU-ol) were prepared by NaBH, reduction of the corresponding alduronic acids. For NMR experiments the compounds were lyophilized three times from D2O. 

Methyl 5-vinylsalicylate was prepared as shown in Scheme II (3). Friedel-Crafts acetylation of methyl salicylate gave the 5-acetyl derivative in 80% yield. Blocking of the phenol followed by NaBH reduction then provided methyl 5-(1-hydroxyethyl)acetyl-salicylate in an overall yield of 70%. The hydroxyethyl compound was dehydrated over KHSO at 225°C/0.2 mm, and the... 

Anthracene is noncarcinogenic and is structurally incapable of forming a bay region diol epoxide. Anthracene 1,2-dihydrodiol is most conveniently synthesized from 2-anthranol by oxidation with phenylseleninic anhydride to anthracene 1,2-dione (55) followed by reduction with NaBH in ethanol (22) or LiAlH (55). Anthracene 1,2-dihydrodiol has also been synthesized via the Prdvost reaction route... 

Selective reduction of ketones.1 Ketones are reduced selectively in the presence of ot,(3-enones by NaBH, in 50% methanol in CH2C12 at -78°. In favorable cases the same selectivity can be achieved at 20° by use of only 5% methanol in CH2C12 and acetic acid as catalyst, but the rate of such reductions is slow. 

Denitration of ally lie nitro groups " Allylic nitro compounds when com-plexed with Pd(0) are reductively removed by a variety of hydride donors. The regioselectivity of denitration to give 1- or 2-alkenes can be controlled by the choice of ligand and by the hydride donor. Thus reduction by formates gives 1-alkenes, and use of NaBH4 or NaBH,CN favors formation of 2-alkenes. 

Two ciT-dihydroxylation reactions of alkenes formed steps in the synthesis of the antiviral drug (-)-oseltamvir ( tamiflu ) were carried out with RuO /aq. Na(IO )/ EtOAc-CH3CN/4°C [169]. Terminal alkene groups in nucleosides were oxidised to alcohols by RuClj/aq. Na(lO )/EtOAc-CH3CN/0°C thus 3,5-di-0-benzyl-l,2-di-O-isopropylidene-3-C-vinyl-a-D-ribofuranose (1) gave the diol (2) which, on cleavage with Na(lO ) and reduction with NaBH yielded 3,5-di-0-benzyl-l,2-di-O-isopropylidene-3-C-hydroxy-methyl-a-D-ribofuranose (3) (Fig. 3.4) [170]. 

Ref 3 [prepn by NaBH reduction of 2-(2-ni-trovinyljpyridine] states that the material is unstable in air., likewise an HCI salt(mp 106-8°), but that a Picrafe sait(mp 129-30° dec) does analyze properly Refs DBeil, not found 2)F.E.Cislak ... 

There are specific catalysts that permit reduction only of C==C.) (c) CHO is selectively reduced by NaBH. ... 

Vitamin B12 also catalyzes the reduction of a nitro group by NaBH+, but less efficiently. 

Prepared by treatment of W-Boc-aspartic acid p-methyl ester with /V-hydroxysuccinimide in the presence of N,N-dicyclohexylcarbodiimide,21 reduction with NaBH, in aqueous THF, and conversion into the iodide using PPh3, l2, and imidazole.22... 

Thus, (-)-frontalin 19 (Scheme 4), pheromone of Dentroctonus Frontalis bark beetle, was obtained from the methyl ketone 12 through the intermediacy of the adduct 20, that was obtained as the sole transformation product by reaction with 4-methyl-pent-4-enylmagnesium bromide in THF. The latter material, once O-benzy-lated, with acid hydrolysis yielded 22, and was then converted into 23 by periodate oxidation, followed by NaBH reduction. 

Pyridoxal-5-phosphate (PLP), an analog of 3PGA or phosphorylated sugars that can be covalently bound to the enzyme by reduction with NaBH ... 

Similarly, the bicyclic ketone 2 (a rcarrangcmcnl product of germinc) is reduced by NaBHj exclusively to the cH oalcohol, and by NaBH(OAc), to the e.vfj-alcohol in 85% yield. The stereoselectivity in the case of 1 is attributed to the presence of a nearby hydroxyl group at C., which exchanges with one of the acetoxy groups of NaBH(OAc),. The selectivity in the reduction of 2 is attributed to a similar complexation of the Cj-hydroxyl group. 

Nucleotide binding sites in proteins can be identified by treating the protein-nucleotide complex with periodate, which cleaves ribonucleotides into highly reactive dialdehydes these are able to couple in a Schiff condensation reaction with the c-amino group of any neighbouring lysine residues (Easterbrook-Smith et al. 1976) (Figure 5-7). This coupling is reversible, but it can be made permanent by reduction with NaBH.. ... 

Ester reduction. A method for the conversion of dicarboxylic acids to CD-hydroxycarboxylic acids involves formation and reduction (with NaBH ) of dilactones in which the two carbonyl residues are linked by tm OCH2O chain. Arylpyruvic esters can be reduced to either the a-hydroxy esters or 1,2-diols. ... 

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