| The optimization of Fe(CO)5 promoted cyclocarbonylation of temporary silicon-tethered diynes is described. Various monomeric cyclopentadienones with hydroxyl substituents were produced in good yields as a result.; Conjugate additions of carbon nucleophiles to these cyclopentadienones and their corresponding protected derivatives were studied. Chelate Mg coordinated cyclopentadienone intermediates were proposed to explain the resulting regio- and stereochemistry. For the mono-protected cyclopentadienone substrates, a hydroxyl-delivery mechanism was proposed.; An unexpected cyclopropanation was observed during the conjugate additions of Grignard reagents to TBS protected hydroxyalkyl-substituted cyclopentadienones. It was prevented after replacing the TBS protecting group with methyl. |
