Sodium borohydride, reaction with compounds

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... 

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. 

The reaction of 4-formyl-3,5-dimethylisothiazole (175) (R = CHO) with sodium borohydride and organometallic compounds (R MgX or R sAl) gives the alcohols (175) (R = CH20H) and (175) (R = CHR OH), respectively. The Wittig reaction on the aldehyde yields the alkenes (175) (R = CH=CHR ) <88JHC235>. 2-Alkyl-5-aroylisothiazolin-3-ones are debenzoylated with sodium hydroxide (see Section 3.05.9.2.1) <87H(25)569>. On heating 2-alkyl-5-aroylisothiazolin-3-ones with phenylhydrazine in ethanol the 3-phenylhydrazono-3-aroylpropionamides are formed (see Section... 

Bcnzo[b]selenoph is and thdr Benzo-fused Derivatives.— The oxo-derivative (511) is a key intermediate in the synthesis of benzo[b]selenophens. Through reduction with sodium borohydride the parent compound is obtained, while reaction with methyl magnesium iodide yields the 3-methyl derivative. Under Vilsmeier formylation conditions, (511) was transformed into 3-chloro-2-formylbenzo[b]selenophen, a useful compound for the fusion of further rings. Compound (511) can also be condensed with aromatic aldehydes to compounds (512), some of them with antibacterial... 

Reduction. Quinoline may be reduced rather selectively, depending on the reaction conditions. Raney nickel at 70—100°C and 6—7 MPa (60—70 atm) results in a 70% yield of 1,2,3,4-tetrahydroquinoline (32). Temperatures of 210—270°C produce only a slightly lower yield of decahydroquinoline [2051-28-7]. Catalytic reduction with platinum oxide in strongly acidic solution at ambient temperature and moderate pressure also gives a 70% yield of 5,6,7,8-tetrahydroquinoline [10500-57-9] (33). Further reduction of this material with sodium—ethanol produces 90% of /ra/ j -decahydroquinoline [767-92-0] (34). Reductions of the quinoline heterocycHc ring accompanied by alkylation have been reported (35). Yields vary widely sodium borohydride—acetic acid gives 17% of l,2,3,4-tetrahydro-l-(trifluoromethyl)quinoline [57928-03-7] and 79% of 1,2,3,4-tetrahydro-l-isopropylquinoline [21863-25-2]. This latter compound is obtained in the presence of acetone the use of cyanoborohydride reduces the pyridine ring without alkylation. 

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). 

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