Anhydrides , imides, N-ethylimides, N-hydroxyimides and N-aminoimides of 1,4,5,6-tetramethylbicyclo[5.2.1.0 2,6 ]hept-5-ene-2,3-dicarboxylic acid, 1,4,5,6,7-pentamethyl-bicyclo[5.2.1.0 2,6 ]hept-5ene-2,3-dicarboxylic acid and 7-ethyl-1,4,5,6-tetramethyl-bicyclo[5.2.1.0 2,6 ]hept-5-ene-2,3-dicarboxylic acid were obtained. Antimicrobial activity of the newly obtained derivatives was tested against selected Gram-positive and Gram-negative bacteria and fungi of the Candida species. The structures of obtained compounds and their antimicrobial activity were compared. Structure of 1b, 2b and 1e were determined by an X-ray analysis.
RESULTS AND DISCUSSIONAnhydrides, imides and N-ethylimides were synthesized in Diels-Alder reaction. Starting compounds were 1,2,3,4-tetramethyl-1,3-cyclopentadiene, 1,2,3,4,5-pentamethyl-cyclopentadiene and 1,2,3,4-tetramethyl-5-ethyl-1,3-cyclopentadiene, which were heated with furan-2,5dione, pyrrole-2,5-dione and 1-ethyl-pyrrole-2,5-dione, respectively. N-amino or N-hydroxyl derivatives were obtained from 1,7,8,9-tetramethyl-, 1,7,8,9,10-pentamethyland 10-ethyl-1,7,8,9-tetramethyl-4-oxa-tricyclo[5.2.1.0 2,6 ]dec-8-ene-3,5-dione with hydrazine hydrate (80%) or hydroxylamine (water solution).The general synthetic pathway and structure of the investigated compounds is given in Scheme I and Table 1.