REACTION OF SOME DIKETONES WITH 5-AMINOLEVULINIC ACID IN ACID-SOLUTION

Some 2,4-diketones react with 5-aminolevulinic acid in acid solution to form pyrroles. There are two modes of cyclisation, one leading to the Knorr and the other to the Fischer-Fink product. By a consideration of the products obtained from pentane-, hexane-, 3-methylpentane-, 3-isopropylpentane-, 3,3-dimethylpentane-, 1,1,1-trifluoropentane-1,1,1,5,5,5-hexafluoro- pentane-2,4-dione and ethyl acetoacetate some generalisations concerning the formation of Knorr and Fischer-Fink products have been made. The reactions of 5-methyl-5-aminolevulinic acid with pentane- and 3-methylpentane-2,4-dione have also been examined, The relevance of these studies to the cyclic dimerisation of 5-aminolevulinic acid is discussed briefly.