Oxidative decyanation

The reaction is an important step in a method for the oxidative decyanation of nitriles containing an a hydrogen. The nitrile is first converted to the a-hydro-peroxy nitrile by treatment with base at — 78°C followed by O2. The hydroperoxy nitrile is then reduced to the cyanohydrin, which is cleaved (the reverse of 16-51) to the corresponding ketone. The method is not successful for the preparation of aldehydes (R =H). 

Nitriles (Table 11)" The oxidative decyanation of nitriles can be efficient and experimentally convenient. In particular, good yields of ketones are obtained from secondary nitriles the reaction is most efficient with the more acidic compounds. Primary nitriles are converted into the corresponding acids, probably via the aldehydes. In the presence of acetic anhydride the reaction stops at the aldehyde diacetate stage. 

Bisdecarboxylation of malonic acids 9-15 Oxidative decyanation of nitriles 9-16 Oxidation of activated or unactivated methylene groups 9-20 Oxidation of secondary alkyl halides and tosylates... 

Oxidative decyanation (6, 430). This reaction can be conducted under phase-transfer conditions with 50% NaOH in DMSO with catalytic amounts of benzyl-triethylammonium chloride (TEBA). The method fails with purely aliphatic nitriles. The highest yields (85-90%) are obtained with aromatic secondary nitriles. 

Polyene cyctization.1 The reaction of C6H5SOCH3 and BF3 with the diene 1 in CH3N02 initiates cyclization to the tricyclic ring system 2 via a sulfenium ion. This product was converted to the diterpene nimbidiol (3) by reductive desulfuration (lithium naphthalenide) and oxidative decyanation (SnCl2), and demethylation (BBrj). 

Halogenated heterocycles (2-, 3-, 4-bromopyridines, 2-chloro-3-bromoquinolines, 2-chloropyrimidine) react with anion 163a. The substitution products then undergo oxidative decyanation under phase-transfer catalytic conditions to afford phenyl hetaryl ketones in good yield (33-77%) (equation 109)202. 

Oxidative decyanation (6,430). Two laboratories have reported regiospedfic syntheses of anthracyclines based on conjugate addition of the enolate of a nitrile to an O, /3-unsaturated ester. For the synthesis of daunomycinone (7), the reaction involved addition of the enolate of 1 to 2 to give 3 in 94% yield. The ester group of 3 was hydrolyzed and the resulting acid was cyclized to 4. Oxygenation of the enolate of 4 by the procedure of Watt results in the quinone 5, which is oxidatively demethylated deketalization of the product led to 6, which had been converted previously into 7. 

In the oxidative decyanation of dialkylaminophenylacetonitriles under phase transfer conditions the generated a-carbanion is oxidized by a stream of oxygen (equation 21) Catalytically, a direct conversion occurs with the system consisting of Pd(OAc)2, benzyl bromide and potassium carbonate. ... 

Oxidative decyanation of phenyl-3-pyridazinylacetonitriles, by passing a brisk stream of oxygen into an aqueous sodium hydroxide/DMSO solution of the substrate containing tri-ethylbenzylammonium chloride, is a convenient method for the synthesis of phenyl 3-pyridazinyl ketones (Scheme 55). Modified reaction conditions allow the one pot conversion of a-(6-chloro-pyridazin-3-yl)phenylacetonitrile into ketones with concomitant hydrolysis or methoxylation of the chloro substituent the direct one pot preparation of 3,6-dibenzoylpyridazine from 3,6-dichloro-pyridazine is achieved in 48% yield <93JHC1685>. 

Cyanopyrazine reacts with cyclopropyllithium to give pyrazinyl cyclopropyl ketone <91JHC1147>. Benzoyl pyrazine is formed by oxidative decyanation of a-pyrazinyl-a-phenylacetonitrile under phase-transfer catalytic conditions <87JHC1061 >. (2-Hydroxy-2-phenylethyl)pyrazines undergo retro-ene reaction on pyrolysis to yield methylpyrazines and benzaldehyde quantitatively <87JOC397i>. 

Amides. Conversion of esters to amides in a solvent-free process uses microwave heating with solid t-BuOK. Oxidative decyanation of a-aminonitriles derived from aldehydes with r-BuOK in DMSO also afford amides. ... 

Oxidative decyanation. Selikson and Watt have converted secondary nitriles, for example (1), into ketones (4) by the following sequence. The anion (a) is generated with lithium diisopropylamide in THF at -78° and then oxygen is bubbled into the solution of (a). A lithium a-cyanohydroperoxide (b) is formed. Quenching with aqueous acid or acetyl chloride provides the isolable a-hydroperoxynitrile (2) or the corresponding acetate. Reduction of (2) leads... 

During an investigation of approaches to the total synthesis of anthracyclinone antibiotics, it has been found that carbanions derived from phenylacetonitrile add to ethyl cyclohex-2-en-l-carboxylate in a Michael fashion to give, after oxidative decyanation, the y-keto-ester (155) in good yield. 

The nitriles obtained by reaction of HPhCN ion with heteroaryl halides can lead to the corresponding ketones in excellent yields (77%) by oxidative decyanation under phase-transfer conditions (PTCs) ... 

Hydroxyl function protecting group (in particular for ribonucleotides). Reagent for oxid. decyanations. Silylation reagent for use in chromatog. Mp 91.5°. BP733 125°. 

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