Metal carbonyl salts CpW(CO) 3 Na, Re(CO) 5 Na, and CpFe(CO) 2 Na were used for intramolecular cyclization of 1-(3-bromo-1-propynyl)-2-(3-oxopropyl)benzene. Among these salts, CpW(CO) 3 Na was found to be the most effective in yielding a metalated fused η 1 -2,5-dihydro-3-furyl complex. To generalize this cyclization, a number of organic substrates containing propargyl bromide and tethered aldehyde or ketone were prepared. Cyclizations of these substrates by CpW(CO) 3 Na proceeded with moderate yields (50%-65%), producing fused tungsten-η 1 -2,5-dihydrofur-3-yl compounds of five-, six-, and seven-membered rings. Demetalations of these organometallic products by (NH 4 ) 2 Ce(NO 3 ) 6 in CH 3 OH/CH 2 Cl 2 under flowing CO provided fused 3-(methoxycarbonyl)-2,5dihydrofurans; the yields were 50-60% for most cases. Consecutive oxidations of the representative η 1 -2,5-dihydrofur-3-yl complex 15 to its fused η 1 -2-furyl and further to η 1 -butenolide derivative were accomplished in good yields. Demetalations of these two fused η 1 -heterocycles were successful for η 1 -butenolide but not for the η 1 -2-furyl derivative.