We tested the following enamines in reaction with N3-C(OEt)=NMs. The reactions were performed in CH2Cl2 at room temperature. Very fast reactions were observed and the first cycloadduct (quite likely a triazoline) could not be detected.
The crude reaction mixtures were chromatographed and the products were characterised by spectral data. The product of ring contraction 6 was transformed into cyclopentanecarboxylic acid by hydrolysis.