Amides manganese dioxide

Conversion of the nitrile to the amide has been achieved by both chemical and biological means. Several patents have described the use of modified Raney nickel catalysts ia this appHcation (25,26). Also, alkaH metal perborates have demonstrated their utiHty (27). Typically, the hydrolysis is conducted ia the presence of sodium hydroxide (28—31). Owiag to the fact that the rate of hydrolysis of the nitrile to the amide is fast as compared to the hydrolysis of the amide to the acid, good yields of the amide are obtained. Other catalysts such as magnesium oxide (32), ammonia (28,29,33), and manganese dioxide (34) have also been employed. 

Nickel peroxide is a solid, insoluble oxidant prepared by reaction of nickel (II) salts with hypochlorite or ozone in aqueous alkaline solution. This reagent when used in nonpolar medium is similar to, but more reactive than, activated manganese dioxide in selectively oxidizing allylic or acetylenic alcohols. It also reacts rapidly with amines, phenols, hydrazones and sulfides so that selective oxidation of allylic alcohols in the presence of these functionalities may not be possible. In basic media the oxidizing power of nickel peroxide is increased and saturated primary alcohols can be oxidized directly to carboxylic acids. In the presence of ammonia at —20°, primary allylic alcohols give amides while at elevated temperatures nitriles are formed. At elevated temperatures efficient cleavage of a-glycols, a-ketols... 

As is true for other classes of aromatic nucleophilic substitution, the halogen displacement can frequently be catalyzed by copper or copper(I) salts. Using sodium hydride as the base and copper(I) iodide as catalyst, a series of o-bromophenylethylamine derivatives, including both amides and carbamates, have been cyclized. Oxidation to the indole can be effected with manganese dioxide (81JCS(P1)290). 

Protopine has been isolated from Bocconia frutescens,110 Fumaria judaica,111 F. schleicheri,112 and Papaver bracteatum,146 cryptopine from F. schleicheri,112 and allocryptopine from B. frutescens110 and Zanthoxylum nitidum.141 The protopine ring-system has been prepared from tetrahydrobenzindenoazepines (75) by photo-oxidation to the amides (76) followed by reduction with lithium aluminium hydride and re-oxidation with manganese dioxide.148-150 The tetrahydrobenzindenoazepines have been prepared from A-chloroacetyl-/ -phenylethylamines (73) by cyclization to the lactam (74) followed by reaction with a benzyl bromide and phosphorus oxychloride. -Protopine (77 R R2 — CH2)148 and fagarine II (77 R1 = R2 = Me)149 have been synthesized in this way. 

Manganese dioxide conveits tertiary amines into amides. For exatiqrle, N,N-dimethylaniline gives N-methyl-N-phenylformamide in 78% yield and N-phenylpyrrolidine yields N-phenylformamide in 48% yield. 4 Dimethylaminocyclohexane on oxidation leads to cyclohexanone in 8S% yield. There is also... 

Carboxylic amides. Gilman has extended the procedure of Corey et at. (2, 261) for oxidation of allylic alcohols to carboxylic esters to the preparation of carboxylic amides. Thus oxidation of aromatic and a,/ -unsaturated aldehydes with Mn02 in the presence of sodium cyanide and an amine gives the corresponding carboxylic amides in high yield. In the absence of sodium cyanide, high yields of nitriles are formed from aldehydes, ammonia, and manganese dioxide. 

Such demethylation takes place often without interception of the form-amide. Dicyclohexylmethylamine, on treatment with potassium ferricya-nide in potassium hydroxide at room temperature overnight, is converted into dicyclohexylamine in 87% yield [926]. Other oxidants suitable for the demethylation of tertiary amines are mercuric acetate in 5% aqueous acetic acid at 100 °C [403], manganese dioxide in cyclohexane at 20 °C [812], and even oxygen, which, under irradiation at 20 °C in the presence of rose bengal in aqueous rm-butyl alcohol, converts codeine into norcodeine in 75% yield [46]. 

With the help of metal catalysis amidation takes place at room temperature under apparently neutral conditions. Manganese dioxide in large quantities, or, even better, manganese dioxide on silica gel, is well suited to this conversion. Even compounds with functional groups labile to manganese dioxide, for example benzylic groups, are suited for the hydration. With pentacarlwnylmanganese bromide, nitrile hydration takes place under PTC conditions. ... 

The oxidation of aldehydes in the presence of amines occurs at low temperatures with nickel perox-ide. Similarly, the oxidation of aromatic aldehydes with manganese dioxide or ruthenium chloride in the presence of sodium cyanide and an amine leads to the corresponding amides. 

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