Microwave-assisted synthesis of tetrahydroindoles

An efficient synthesis of tetrahydroindoles with different substituents in position 1 is described. Microwave-assisted aminolysis of 4-oxo-4,5,6,7-tetrahydrobenzofuran with different primary amines gives the corresponding tetrahydroindoles in few minutes. All attempts to use microwave dielectric heating to reduce the time required for preparation of 4-oxo-4,5,6,7-tetrahydrobenzofuran, starting from 1,3-cyclohexandione were on the other hand unsuccessful, demonstrating that in some cases, long time conventional heating may be superior to microwaves.