Propargyl azides

Heated in methanol for an extended period of time, propargyl azide 1147 experiences a [3,3] sigmatropic shift to allenyl azide 1148 that undergoes rapid cyclization to triazafulvene 1149. Addition of a molecule of methanol converts reactive intermediate 1149 to triazole 1150 that is isolated in 68% yield. In concentrated solutions, two molecules of intermediate 1149 may undergo cycloaddition to form dimer 1151 as a side product (Scheme 189) <2005EJ03704>. 

There is still no successful approach to 1-azidoalkynes, although the corresponding phenyl derivative (23 Scheme 35) is thought to be a short-lived intermediate in the reaction of chlorophenylacetylene with azide ions." " In contrast to this, propargylic azide (24) and its higher homologs (25) can be obtained in the usual way." The formation of these compounds is sometimes accompanied by rearrangements, which also very often take place with azidoallene derivatives their chemistry was intensively studied recently by Priebe" and Banert. ... 

Propargyl azide, 5ee 3-Azidopropyne, 1114 t Propargyl bromide, see 3-Bromopropyne 1090 t Propargyl chloride, 5ee 3-Chloropropyne 1092 t Propenal, see Acrylaldehyde, 1145... 

Scheme 5.33 Generation of allenyl azides by [3,31-slgmatroplc rearrangement of propargyl azides and transformation of these short-lived intermediates into 1,2,3-triazoles and Diels-Alder products (NuH = nudeophllef ...

The knowledge of the surprising unimolecular reactions of propargyl azides shown in Schemes 5.32 and 5.33 offered the possibility to develop a one-pot procedure for the synthesis of 1,2,3-triazoles of type 270 (Scheme 5.35). When a small excess of the starting material 266 was treated with sodium azide, the resulting solution of azide 267 yielded the hnal product 270 after heating with an excess of the nucleophile... 

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