Diazomethane reaction with amines

The reactions with nucleophiles include a wide variety such as amines, sulfides (133,135), diazomethane (111), and others. Of particular interest were the reactions of such intermediate iminium salts with 2,3-dimethyl-butadiene to give cyclic products as shown in the reaction of N-bromo-methylpiperidine and N-bromo- and N-chloromethyldiethylamine (134). 

The reaction of diazo compounds with amines is similar to 10-15. The acidity of amines is not great enough for the reaction to proceed without a catalyst, but BF3, which converts the amine to the F3B-NHR2 complex, enables the reaction to take place. Cuprous cyanide can also be used as a catalyst. The most common substrate is diazomethane, in which case this is a method for the methylation of amines. Ammonia has been used as the amine but, as in the case of 10-44, mixtures of primary, secondary, and tertiary amines are obtained. Primary aliphatic amines give mixtures of secondary and tertiary amines. Secondary amines give successful alkylation. Primary aromatic amines also give the reaction, but diaryl or arylalkyl-amines react very poorly. 

The formation of isocyanates has also been observed in reactions outlined in equations (21)-(23). It has been shown that the reactions of equation (21) most probably proceed via coordination of the amine function followed by rearrangement with elimination of HX. The reaction with PPh3 is interesting because of the initial formation of a nitrene species via N—O bond cleavage. Formation of a nitrene intermediate as a crucial step in the formation of the NCO ligand has also been proposed for the reaction with diazomethane. 

Reactions of cyclopropanones with nucleophiles frequently lead to ring enlargement reactions since the formation of four-membered rings from the reactive intermediates is accompanied by a considerable reduction in strain energy. Thus, 2 reacts with diazomethane to form cyclobutanone96>, with hydrazoic acid to form (3-lactam 76,89) and, under special conditions, with amines and hydroxyl amine derivatives to form N-sub-stituted (3-lactams 87> (Scheme 24). 

Palladium-catalyzed methylene transfer from diazomethane has proved effective for the cyclopropanation of 1-alkenylboronic acid esters allylic alcohols and amines 1-oxy-l,3-butadienes and allenes " Readily accessible iron complex (CO)2FeCH2S Me2 BF4 35 undergoes direct reaction with a range of alkenes to give cyclopropanes (equation 67) The salt is sensitive to steric effects and the reaction proceeds... 

Bis(trifluoromethyl)diazomethane is a reactive, electrophilic compound. It forms adducts with nucleophiles such as amines and phosphines5 and adds to olefins, acetylenes,5 and thiocar-bonyl compounds6 to form heterocycles. It has been used as a source of bis(trifluoromethyl) carbene in reactions with benzene,5 saturated hydrocarbons,7 carbon disulfide,8 and transition metal compounds,8 and it undergoes a unique radical chain reaction with saturated hydrocarbons to form adducts that are hydrazoncs and azines.7... 

Five-membered O-heterocycIic derivatives of the type dihydrobenzofuran (352 in Fig. 137) are formed by reaction with diazomethane or analogous reagents. It is to be stressed, in partieular, that the deamination of a Mannich base may be favored by the formation of amine N-oxide, instead of the corresponding quaternary ammonium salt, as is usually required. 

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