Use of Alkyl Azides

A-Sulfonylamidines can be prepared by three-component coupling [31] of alkynes (R = alkyl, aryl or silyl), sulfonyl azide and amine, which is known as click chemistry. [32] The use of alkyl azides in place of sulfonyl azide without a copper catalyst results in the formation of 1,2,3-triazoles (Scheme 3.18). This reaction shows substrate tolerance to each component. Reaction with an optically active amino ester is performed without racemiza-tion. A-Boc-ynamide (R = NPhBoc) can act as the alkyne component in the synthesis of N-Boc-aminoamidines [33]. 

The use of alkyl azides (Alk-Ns) or aryl azides (Ar-Ns) can yield the corresponding substituted 1,5- or 2,5-tetrazolene, 1,4-tetrazoUnones and/or the corresponding mer-captotetrazoles. Moreover, substituted 1,2,3-triazoles are feasible and also aziridines provided that the azide was thermally or photochemically converted by separation of the nitrogen or by decomposition of the resulting dihydro-l,2,3-tiiazole. 

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