Structures of bromo-substituted pyrone-4-carboxylic acids obtained by direct bromination

Ethyl esters of mono- and dibromocomanic acid were obtained by direct bromination, and the corresponding acids were obtained from the esters by acid hydrolysis. The structures of the compounds obtained and of the previously synthesized bromo-substituted comanic acid were established, and it was proved that the attack of bromine is directed to the 5-C and 3-C atoms; attack takes place first at the more nucleophilic 5-C center, after which the 3-C atom undergoes attack.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 901–903, July, 1978.