ABSTRACT SYNTHESIS OF FERROCENYL CYCLOPENTENONES TUMAY, T&uuml / lay Asli M.S., Department of Chemistry Supervisor: Assoc. Prof. Dr. Metin Zora August 2005, 80 pages Construction of highly functionalized five-membered rings via cycloaddition reaction of cyclopropylcarbene-chromium complex with alkynes has become a very active area of research in recent years by virtue of their presence in antitumour natural products. Also with the finding that ferrocene derivatives are active against various tumours, considerable interest has been devoted to the synthesis of new ferrocene derivatives since properly functionalized ferrocene derivatives could be potential antitumour substances. So, the incorporation of the essential structural features of cyclopentenones with a ferrocene moiety could provide compounds with enhanced antitumour activities. For this purpose, we have investigated the reaction between cyclopropylcarbene-chromium complex and ferrocenyl alkynes. The reaction of cyclopropylcarbene-chromium complex with ferrocenyl alkynes afforded &amp / #945 / -hydroxycyclopentenones in a one-pot process, whereas the same reaction with alkynes gave cyclopentenones as major products. Interestingly, water addition was observed instead of reduction according to the previously proposed mechanism. This is a different result than those in literature. The reaction was regioselective both with terminal ferrocenyl alkynes and internal unsymmetrical ferrocenyl alkynes. The products obtained were those where the sterically larger alkyne substituent, ferrocene, was &amp / #945 / to the carbonyl group.