Synthesis and Structure Analysis of 1-(2-Chlorobenzoyl)-3,6-Diphenyl-1,4-Dihydro-1,2,4,5-Tetrazine

Abstract

1-(2-Chlorobenzoyl)-3,6-diphenyl-1,4-dihydro-1,2,4,5-tetrazine was prepared from 2-chlorobenzoyl chloride and 3,6diphenyl-1,2(or 1,4)-dihydro-1,2,4,5-tetrazine, and its structure was determined by X-ray diffraction. This reaction yields the 1,4-dihydro derivative rather than the 1,2-dihydro derivative. The central six-member ring of the title compound exhibits a boat conformation and therefore, is not homoaromatic.

Synthesis and Structure Analysis of 1-propionyl-3,6-diphenyl-1,4-dihydro-1,2,4,5-tetrazine

“…1,2,4,5-Tetrazine derivatives have been widely used in medicinal chemistry and organic synthetic chemistry. [1][2][3][4][5][6][7] Dihydro-1,2,4,5-tetrazine has four isomers, namely 1,2-, 1,4-, 1,6-and 3,6-dihydro-1,2,4,5-tetrazine. Homoaromatic structures have been demonstrated by X-ray diffraction in the 1,6-dihydro structures.…”

“…8 But there is still some doubt as to whether 1,4dihydro structures have homoaromaticity. For instance, X-ray diffraction was reported to show that several 1,4-dihydro-1,2,4,5-tetrazine derivatives have an obvious boat conformation without a homoaromatic structure, [4][5][6][7] and 3,6-bis(4-chlorobenzyl)-1,4-dihydro-1,2,4,5-tetrazine have an obvious chair conformation without a homoaromatic structure 9 . But 1,3,4,6tetramethyl-1,4-dihydro-1,2,4,5-tetrazine was analysed by X-ray diffraction and Bemis et al 10 deemed that this potentially antiaromatic or homoaromatic ring system had a flattened boat conformation with both N-methyls in equatorial positions.…”