The synthetic utility of tert-butyl azidoacetate (7) on the Hemetsberger-Knittel reaction is described. The following two findings are disclosed by using tert-butyl azidoacetate (7): i) in the first step for the synthesis of ethyl indole-2-carboxylate 4, the aldol reaction of less reactive aldehydes 1a, b was improved greatly; ii) tert-butyl indole-2-carboxylate 10 becomes readily available from aldehydes.
[Kim, Dong H.; Guinosso, Charles J.; Buzby, George C.; Herbst, David R.; McCaully, Ronald J.; et al. Journal of Medicinal Chemistry, 1983 , vol. 26, # 3 p. 394 - 403]
