Diversity-Oriented Reconstruction Of Primitive Diketopiperazine-Fused Tetrahydro-Beta-Carboline Ring Systems Via Pictet-Spengler/Ugi-4cr/Deprotection-Cyclization Reactions

An expedient construction of tetrahydro-beta-carbolinediketopiperazine ring systems, which are present in various indole alkaloids, is documented. The synthetic strategy proceeds through a Pictet-Spengler reaction followed by an Ugi-4CR and deprotection-cyclization reactions. This is the first report of a Pre-Ugi multicomponent reaction modification using 2,3,4,9-tetrahydro-1H-pyrido[3,4-b]indole-1-carboxylic acid as the acidic partner. This novel approach provides highly diverse reconstructions of novel tetrahydro-beta-carbolinediketopiperazine derivatives, which can also be used as privileged structures in medicinal chemistry.