Chromium , pentacarbonyl dihydro

The following procedure can be extended to prepare l-oxacyclopent-2-ylidene chromium complexes substituted in the 3 or 5 position.4 Thus the reaction of the anion of pentacarbonyl(l-methoxypropylidene)chromium(0) with ethylene oxide gives pentacarbonyl [dihydro-3-methyl-2(3//)-furylidene] chromium(O) [pentacarbonyl(3-methyl-l-oxacyclopent-2-ylidene)chromium(P)], and the reaction of the anion of pentacarbonyl(l-methoxyethylidene)chromium(0) with propylene oxide gives pentacarbonyl(dihydro-5-methyl-2(3//)-furanylidene)-chromium(O) [pentacarbonyl(5-methyl-l-oxacyclopent-2-ylidene)chromium(0)]. 

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