Sequential one-pot five-component synthesis of tetrazole-based spirotetrahydro-β-carbolines

Abstract

A one-pot five-component two-step sequential synthesis of tetrazole-based tetrahydrospiro[indene-2,1′-pyrido[3,4-b]indole]-1,3-diones in moderate to good yields is described. The reaction consists of four-component condensation of aromatic aldehydes with tryptamine, trimethylsilyl azide (TMSN3) and isocyanides, followed by addition of ninhydrin. These reactions presumably proceeded through Ugi-azide/Pictet–Spengler processes, respectively.