We recently reported that molybdenum pentacarbonyl will cyclize 1-alkyn-4-01s to the isomeric 2, 3-dihydrofurans. 2.3 Although the generation of Mo (C0) s from trimethylamine N- oxide and molybdenum hexacarbonyl produces a modestly catalytic reagent for this cycloisomerization, we have found that EtSN: Mo (C0) s is best prepared by photolysis Of Mo (CO) 6 in a mixture of diethyl ether and triethylamine (Rayonet lamp, 350 nm, pyrex filter, ...
