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Historically, the synthesis of diazoacetic acid ester by Curtius in 1883 1 and its reaction with unsaturated carboxylic esters reported by his younger colleague, Buchner, in 1888 may constitute the embryonic events in the discovery of 1, 3-dipolar cycloadditions. 2 Important contributions in subsequent years by Buchner, 2 Beckmann, 3 Werner, Buss, 4 and others for the generation of 1, 3-dipoles are also noteworthy. This field, however, lay dormant until 1963, when Huisgen, recognizing the generality of these reactions, created the conceptual framework for the 1, 3-dipolar cycloadditions (Huisgen reaction) and provided the much-needed mechanistic rationalization for the process. 5 He invoked the intermediacy of dipoles in some well-known reactions. Later, Sustmann classified the dipolar cycloaddition reactions into three types based on the orbital interactions. 6 With a better understanding of the mechanistic events …