Atypisches Verhalten von Thiophenderivaten gegeniiber Reduktions- bzw. Thionierungs-Versuchen

To prepare required thiolactarns. initial experiments were done with the lactarns 1 - 3 and Lawessol reagent. However in preliminary trials. treatment of the compounds failed to give the desired molecules. Modification of the reaction conditions. paticularly with regard to the solvent and the reaction temperature. did not permit the preparation of the corresponding thiolactams. The keto function in position 6 was thought to be responsible for this atypical behaviour. Therefore. as the following step. the acetyl group in compounds 1 - 3 should be reduced to the corresponding ethyl derivatives. This reaction did not give the needed bicycles. Reduction of compounds 4 - 6 with triethylsilanel trifluoroacetic acid brought up compounds 7 - 9.