Synthesis of the ethyl oxalyl tetracarbonyl iron anion [(CO)4FeCOCO2Et]–, its methylation at the metal into (CO)4Fe(Me)(COCO2Et) and further carbon–carbon coupling into ethyl pyruvate
Abstract
The stable anion [(CO)4FeCOCO2Et]–(2)[obtained after reaction of EtOCOCOCl on Na2Fe(CO)4] is methylated at the metal by reaction with MeSO3CF3 at –50 °C to give (CO)4Fe(Me)(COCO2Et)(3) characterized in situ by 1H and 13C NMR; at –30 °C it decomposes according to two pathways: reductive elimination into MeCOCO2Et (4) and Fe3(CO)12 and rearrangement into (CO)4Fe(COMe)(CO2Et)(5) which decarbonylates at +5 °C before giving MeCO2Et (6) and Fe(CO)5.