Synthesis of 1-aryl-1,2,3,4-tetrahydro-9H-pyrido[3,4-b]indoles (1,2,3,4-tetrahydro-beta-carbolines) under high pressures

The reactions of aromatic aldehydes with tryptamine (1) in solvents of diff erent polarity were studied. The yields of carbolines in the chosen media d ecrease with ail increase in the donating properties of the aryl substituen t, but they markedly increase at a high pressure (5 kbar), especially for c ompounds with electron-donating aryl groups. The phase transition of dioxan e at 5 kbar also sharply increases the yields of the target products.