Sodium cyanoborohydride/titanium

The reductive ring opening of 330a with sodium cyanoborohydride/titanium tetrachloride in acetonitrile occurs with no ester reduction whatsoever to provide 421 in 83% yield. Subsequent conversion to the tosylate followed by reduction with lithium borohydride/lithium triethylborohydride affords in 61% yield the crystalline diol 422. Lithium aluminum hydride or sodium borohydride reduction of the tosylate of 421 fails to produce clean reductions to 422. Epoxide ring closure of 422 is achieved with two equivalents of sodium hydroxide in methanol to fiimish in 93% yield (2 S, 3i )-2-benzyloxy-3,4-epoxybutan-l-ol (423) [140] (Scheme 94). 

Tertiary amine TV-oxides are rapidly deoxygenated by carbon disulphide1112. Oximes are reduced to primary amines by titanium(III) chloride in the presence of sodium cyanoborohydride, NaBTpCN1. The combined action of sodium borohydride and a chiral... 

Hydrazones treated with alkalis decompose to nitrogen and hydrocarbons [845, 923] Woljf-Kizhner reduction) (p. 34), and p-toluenesulfonylhydra-zones are reduced to hydrocarbons by lithium aluminum hydride [812], sodium borohydride [785] or sodium cyanoborohydride [813]. Titanium trichloride hy-drogenolyzes the nitrogen-nitrogen bond in phenylhydrazones and forms amines and ketimines which are hydrolyzed to the parent ketones. Thus 2,4-dinitrophenylhydrazone of cycloheptanone afforded cycloheptanone in 90% yield [202]. 

During their synthesis of the Dactomelynes, Lee and co-workers employed sodium cyanoborohydride and titanium(IV) chloride95 to accomplish the regiose-lective cleavage of a benzylidene acetal [Scheme 3,57].%... 

Within the first pathway, reduction of the nitrile was facilitated by preliminary methylation with dimethylbromonium hexafluoroantimonate in liquid sulfur dioxide and subsequent methanolysis to the iminoether, which was treated with sodium cyanoborohydride (Scheme 20). The secondary amine 191 was chlorinated with sodium hypochlorite to the corresponding iV-chloroamine to enable titanium... 

LACTAMS Di-n-butyltin oxide. Hy-droxylamine-O-sulfonic acid. Iodine azide. Sodium cyanoborohydride. (3-LACTAMS Cyanuric chloride. Grignard reagents. Ion-exchange resins. Lithium phenylethynolate. Sodium dicarbonyl-cyclopentadienylferrate. Titanium(III) chloride. Titanium(IV) chloride. Tri-phenylphosphine-Carbon tetrachloride. Triphenylphosphine-Diethyl azodicar-boxylate. Triphenylphosphine-2,2 -Dipyridyl disulfide. 

Carbonyl compounds include isobut3raldehyde, phenyl isopropyl ketone, glyoxylic acid and pyruvic acid. Diaryl ketones do not react. Modifications of the method consist in the use of a borohydride exchange-resin, of sodium triacetoxyborohydride NaBH(OAc)3 or in treating a mixture of a ketone and an amine with an equivalent of titanium(IV) chloride and Hiinig s base (ethyldiisopropylamine) in dichloromethane, followed by a methanolic solution of sodium cyanoborohydride. The borane-pridine complex and hydrogen telluride are excellent replacanents for sodium cyanoborohydride. 

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