Halides, alkyl reaction with cyanamide

VOll Braun reaction. Reaction of tertiary amines with cyanogen bromide to form disubsti-tuted cyanamides and an alkyl halide. 

Alkylation with a vatiety of common alkyl halides oi sulfates gives stable dialkylcyanamides. However, the intermediate monoalkylated compounds usually cannot be isolated and cychc trimers or cotrimers with cyanamide ate obtained (13). The reaction can be carried out efficientiy in water or alcohol. Allyl chloride is an especially useful reagent, producing diallylcyanamide [538-08-9J (4). 

A convenient way of obtaining secondary amines without contamination by primary or tertiary amines involves treatment of alkyl halides with the sodium or calcium salt of cyanamide NH2—CN to give disubstituted cyanamides, which are then hydrolyzed and decarboxylated to secondary amines. Good yields are obtained when the reaction is carried out under phase-transfer conditions. The R group may be primary, secondary, allylic, or benzylic. 1, co-Dihalides give cyclic secondary amines. 

An efficient synthesis of 2-amino derivatives 256 is depicted in Scheme 70 2-halopyridines are first Ar-alkylated with various halides under microwave activation and next reacted with cyanamide under basic conditions <1999T2317>. A rapid parallel synthesis of derivatives bearing a benzoyl substituent at C-3 based on this reaction has been described <2002SL1544>. 

The preparation of diallyl cyanamide by the above method has only recently been described in the literature.1 However, other dialkyl cyanamides have been prepared by the following methods the action of chlorocyanogen or bromocyanogen on dialkyl amines 2 the reaction of dialkylchloroamines with potassium cyanide 3 the action of bromine on a mixture of dialkyl amines and potassium cyanide 4 the action of alkyl halides on disilver cyanamide5 and on disodium cyanamide.6 Dimethyl cyanamide has also been prepared by the action of dimethyl sulfate on lime nitrogen 7 and on cyanamide. 8... 

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