Pyridinium chlorochromate oxidation amines

Pyridinium chloride, N-(4-pyridyl)-hydrochloride quaternization, 2, 175 reactions with amines, 2, 241 Pyridinium chlorochromates as oxidizing agents, 2, 170 reactions, 2, 34 Pyridinium dichromate as oxidizing agent, 2, 170 Pyridinium l-dicyanomethylide... 

Entries 5 to 7 are examples of oxidation of boranes to the carbonyl level. In Entry 5, chromic acid was used to obtain a ketone. Entry 6 shows 5 mol % tetrapropylam-monium perruthenate with Af-methylmorpholine-lV-oxide as the stoichiometric oxidant converting the borane directly to a ketone. Aldehydes were obtained from terminal alkenes using this reagent combination. Pyridinium chlorochromate (Entry 7) can also be used to obtain aldehydes. Entries 8 and 9 illustrate methods for amination of alkenes via boranes. Entries 10 and 11 illustrate the preparation of halides. 

Oxidation of 8-hydroxymethyl-2-isopropyl-l 1 //-pyrido[2,l-b]quinazolin-11-one with pyridinium chlorochromate in methylene chloride gave the 8-carboxaldehyde, which was converted into its 8-aminomethyl derivatives by reacting with amines followed by reduction of the Schiff bases with sodium cyanoborohydride in acetic acid (87JOC2469). 

Nickel peroxide. Oxoperoxobis(N-phenylbenzohydroxamato) molyb-denum(VI). Palladium(II) acetate-Tri-phenylphosphine. Palladium /-butyl peroxide trifluoroacetate. Periodic acid. Permonophosphoric acid. Potassium dichromate. Potassium hydrogen persulfate. Pyridinium dichromate. Ruthenium tetroxide. Selenium dioxide. Sodium hypochlorite. Titanium(IlI) chlo-ride-Hydrogen peroxide. Potassium nitrodisulfonate. Potassium peroxodi-sulfate. Pyridinium chlorochromate. Pyridinium chlorochromate-Hydrogen peroxide. Sodium permanganate monohydrate. Tetra-n-Butylammonium periodate. Thailium(III) acetate. Trimethyl-amine N-oxide. Triphenylmethylphos-phonium permanganate. 

Finally, Han, Huang, and Peng reported a multicomponent cascade reaction for the synthesis of the spirooxindole pyranone scaffold [38]. The reaction started with the addition of aliphatic aldehydes 15 to nitrostyrenes 64 catalyzed by chiral secondary amine catalyst I. Next, the resulting adduct reacted with A-benzyl isatin (54b) by a Henry-hemiacetal formation cascade followed by pyridinium chlorochromate (PCC) oxidation to afford the corresponding spirooxindoles 70 in good yields and stereoselectivities (Scheme 10.24). 

In 2003, the first organocatalytic enantioselective inverse-electron-demand hetero-Diels-Alder reaction of p,Y-unsaturated-a-ketones 97 with aldehydes 98 promoted by a secondary amine catalyst (99) was accomplished by the j0rgensen group (41). After oxidation by pyridinium chlorochromate (PCC), various trans-lactones 100 were afforded with good yields and up to 94% ee (Scheme 38.27). The reaction is proposed to occur via an enamine intermediate generated from chiral secondary amine 99 and aldehydes 98 (transition state O). Notably, sUica gel is essential for regeneration of the chiral amine catalyst. 

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