The reactions of alkoxyacetylenes have been extensively investigated in recent years, mainly by Arens and co-~ orkers.~ It was found that one mole of methoxy-or ethoxyacetylene reacts rapidly at room temperature with two moles of a variety of carboxylic and other acids to produce the corresponding anhydrides in good yield. 4 This reaction has been assumed to occur by the intermediate formation of 1-alkoxyvinyl esters (I) and 1-alkoxyethylidene ...