M. Ishikura et al., Cycloaddition reaction of 2-allenylindoles with diethyl acetylenedicarboxylate under thermal and high pressure conditions, J HETERO CH, 38(3), 2001, pp. 675-678
The cycloaddition reaction of 2-allenylindoles 2 with diethyl acetylenedica
rboxylate 6 was undertaken under both thermal and high pressure reaction co
nditions, leading to carbazole derivatives 5.