“…Since compounds 3 a,b represent the first and only examples of 4,5-dihydro-1,2,3,4-oxatriazoles, the results reported in 2002 were cited and reviewed repeatedly. [2] The well-known [3] transformation of 4 a and 4 b into 5 a,b and 5 c, respectively, seems to be similar to the formation of 3 a,b from 2 a,b. However, the question arises whether the carbonyl group of an aldehyde and an azido unit are thermodynamically more favorable than a nonaromatic 4,5-dihydro-1,2,3,4-oxatriazole that includes a weak O À N single bond.…”