Synthesis of ferrocenyl cycloheptadienones

Açıkgöz, Canet
Synthesis of seven-membered ring systems such as cycloheptadienones has attracted a great deal of attention in organic chemistry since they are present in a variety of biologically important molecules. Incorporation of the essential structures of such compounds with a ferrocene moiety instead of an aryl group could provide subtances with enhanced antitumor activities since some ferrocene derivatives have already proved to be active against a number of tumors. To develop a ferrocenyl-substituted seven-membered ring forming reaction, we have investigated the reaction of cyclopropylcarbene-molybdenum complex with ferrocenyl-substituted alkynes. As ferrocenyl-substituted alkyne, ferrocenylpropyne (25B), (2-ferrocenylethynyl)trimethylsilane (25C), 1-ferrocenyl-3-phenylprop-1-yne (25D), 1-ferrocenyl-2-phenylethyne (25E), diferrocenylethyne (25F), ferrocenyl(formyl)acetylene (25G) were synthesized starting from ethynylferrocene (25A). The reaction between cyclopropylcarbene-molybdenum complex and ferrocenyl alkynes produced ferrocenyl-substituted cycloheptadienones 26, hydrolysis product of cycloheptadienones, 27, ?-hydroxycycloheptadienones 28 and cyclobutenones 29, depending on the substitution pattern of the alkyne moiety. Interestingly, ?-hydroxycycloheptadienone product 28B was isolated from these types of reactions for the first time. Terminal alkynes, trimethyl- and formyl-substituted alkynes did not produce any expected product, possibly depending on the steric and electronic effects, and/or the polymerization of the alkyne. Proposed mechanism for the formation of cycloheptadienones involves metallacyclobutene formation, electrocyclic ring opening, electrocyclic ring closure, CO insertion, reductive elimination.


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Citation Formats
C. Açıkgöz, “Synthesis of ferrocenyl cycloheptadienones,” M.S. - Master of Science, Middle East Technical University, 2005.