Cyanogen azide, cycloaddition reactions

The reaction of cyanogen azide with enamines of cyclic ketones to yield a cyanoamidine with one less member in the carbocyclic ring represents a potentially valuable method of ring contraction under mild conditions (199a). The reaction probably proceeds first by 1,3 cycloaddition of the azide to the enamine followed by rearrangement and elimination of a molecule of nitrogen. 

Similarly, the regiospecific 1,3-dipolar cycloaddition reaction of 1-methyl-1,2-dihydropyridines 41 with cyanogen azide (50a) and selected organic azides 50c and 50g afforded 2-methyl-2,7-diazabicyclo[4.1.0]hept-4-enes 57, which can be elaborated to 1-methyl-l,2,5,6-tetrahydropyridylidene-2-cyanamide (58) and 1-methyl-2-piperidylidenes 59a-d (85CJC2362). 

Azidotetrazole can be prepared by several methods. The simplest method is the direct cycloaddition reaction between alkaline azides and cyanogen halogen. An alkaline salt of 5-azidotetrazole forms according to the following reaction [81,82] ... 

A). The reactions of hexamethyl(Dewar)benzene with these azides occur without structural rearrangement, in contrast to the rearrangements during its reactions with cyanogen azide for example. The difference has been ascribed to the difference in mechanism the unrearranged products are from a concerted cycloaddition and the rearranged products are formed in an addition which involves an initial electrophilic attack. 

Apparently the simplest S-fluorotetrazole 18 and its derivatives can be synthesized by the reaction of 2+3 dipolar cycloaddition of azides to cyanogen fluoride or by some other method. Yet we failed to find the mention of such synthesis in available publications. The possibility of this reaction and its mechanism were assessed theoretically [37]. Publications are known where compound 18 is used as a component of the energy-rich compositions [38],... 

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