β-Carbolines as intermediates in indirect heteroarylation of tryptamines exemplified by the synthesis of 2-pyrazolyltryptamines

A cyclization–recyclization pathway for indirect 2-heteroarylation of tryptamines has been suggested by the example of introducing the pyrazolyl moiety. The process involves the intermediate cyclization of tryptamines into push–pull type β-carboline semi-products. The relative stability of the tautomeric forms of 2-pyrazolyltryptamines has been estimated using the DFT method.