A plausible route including two steps for this nitrile one-pot synthesis is illustrated in Scheme 1. Initially, the attack of hydroxylamine hydrochloride to aldehyde gives an intermediate oxime M1c, which then undergoes triphosgeneassisted dehydration to give the desired nitrile product P1c. In this process, there is no doubt about the reaction mechanism of the first step. To investigate the acting property of triphosgene for these oximes, and confirm that the reaction mechanism of the conversion of oxime to nitrile, as described in Scheme 2, 1c-22 was selected as a representative, 1 H NMR titration experiments and GC analyses were carried out. H NMR spectra recorded after adding triphosgene to a solution of benzaldehyde oxime in CD3CN (Figure ), which showed that the hydroxyl proton (Hd) signal at 8.9 ppm disappeared and the formyl proton (Hc) signal at 8.3 ppm of benzaldehyde oxime shrunk gradually after the addition of triphosgene, and aldehydic proton signals sharply appeared at 10.1 ppm (Ha), while the proton signal of benzonitrile arose at 7.7 ppm (Hb'). In addition, based on the GC analysis of that final reaction solution, the same result as 1 HNMR including benzaldehyde and benzonitrile was obtained and shown in Figure . As for acetophenone oxime, the hydroxyl proton (He) signal at 8.85 ppm disappeared as well as the Ar-H (7.65 ppm) and -CH3 (2.25 ppm) signals were shifted (Hb'' to Hb'and Hb; Hd to Hc and He). indicating the conversion of oxime to amide and ketone and shown in Figure . As a result, acetanilide and acetophenone were formed, and the GC data also verified this conclusion (Figure ).