Previously, 1 was prepared from the corresponding chlorolb or bromo1* compounds, which were in turn made by using the gaseous hydrogen halides. The commonly used preparation2g of 2 begins with the A1C13-catalyzed reaction of acetyl chloride with gaseous ethylene. The resulting chloro ketone was treated with sodium iodide and fiially ketalized in 56% overall yield. Another alternative2h begins with ketalization (neopentanediol) of ethyl ...
