A concise and efficient route for the synthesis of indole derivatives having propellane structure at position 3
by simple regioselective one-pot reaction of ninhydrin, malononitrile, tryptamine, and β-dicarbonyl compounds was developed.
This protocol provides an alternative method for application in combinatorial and parallel synthesis in drug discovery.
The value of this method lies in its simplicity, regioselectivity, and good yields. The structures of new synthesized
compounds were corroborated spectroscopically (IR, 1H- and 13C-NMR, and EI-MS). A plausible mechanism for this type
of reaction is proposed (Scheme 2).