Thermal Behavior of Tetrazoles and Triazoles under Flash Vacuum Pyrolysis Conditions

PAOLA LUCERO; ELIZABETH L. MOYANO; ZSUZANNE RIEDL; GYORGY HAJOS; GLORIA I. YRANZO

LOS COCOS-CORDOBA

Conferencia; 9th Latin American Conference on Physical Organic Chemistry; 2007

Flash Vacuum Pyrolysis (FVP) is an appropriate technique for the preparation of many organic compounds, isolation of reactive species, and for mechanistic study of thermal reactions. In this work we studied the thermal behavior of (2E)-3-[2-(4-chlorophenyl-2H-tetrazol-5-yl]acrylaldehyde (1), (2E)-3-[2-(4-methoxyphenyl-2H-tetrazol-5-yl]acrylaldehyde (2), (2E)-3-(1-(4-chlorophenyl-1H-1,2,3-triazol-4-yl)acrylaldehyde (3) y de (2E)-3-(1-(4-methoxyphenyl-1H-1,2,3-triazol-4-yl)acrylaldehyde (4) under FVP conditions finding interesting differences in their reactivity. In the FVP of tetrazoles 1 and 2 the only reaction found was nitrogen extrusion at 280 ºC affording the corresponding indazoles 5 and 6 as major products in good yields. On the other hand, when we performed the pyrolysis of triazoles 3 and 4 it was found  nitrogen extrusion reaction at 380 ºC and the major products detected were the corresponding indoles 7 and 8 as well as furan-benzenamines 9 and 10. (Scheme 1). These reactions are proposed to take place through a similar carbene intermediates which have two different cyclisation reactions depending on the presence of one or two nitrogen atoms. These reactions are proposed to take place through a similar carbene intermediates which have two different cyclisation reactions depending on the presence of one or two nitrogen atoms. These reactions are proposed to take place through a similar carbene intermediates which have two different cyclisation reactions depending on the presence of one or two nitrogen atoms.