Hexadecarboxylative Synthesis of Hexaazatriphenylene.

摘要

Thermal decarboxylation of hexaazatriphenylene hexacarboxylic acid in diphenyl ether (230 C for 20h) with added copper powder affords the parent heterocycle, hexaazatriphenylene, in 44% yield after filtration through an alumina plug. We now report that HAT may be prepared via the hexadecarboxylation of HAT (COOH)6 a compound whose synthesis we have reported via a three-step sequence. Thermal decarboxylations of heterocyclic alpha carboxylic acids have long been reported as preparatively useful in for example, the pyrazine series: the mono-, di-, tri-, and tetracarboxylic acid derivatives of 1,4-pyrazine all afford pyrazine itself under appropriate conditions. The decarboxylation of hexaacid 1 occurs best in diphenyl ether with added copper powder. The resulting solid sample is identical to HAT prepared as previously described in every respect, and is of analytical purity. This route, which is four steps from commercially available precursors,does not involve the intermediacy of potentially explosive precursors and may be preferable to that reported recently in some situations. Reprints. (AW)