In previous papers we have reported that liquid-phase reactions of anhydrous hydrogen bromide28 and hydrogen chloride 2,495 with a series of monoalkylacetylenes resulted partly in 2+ 2 cycloadditions to afford products having four-membered ring structures. By contrast, in the reaction of excess hydrogen chloride with the dialkylacetylene 2-butyne under similar conditions, only 2, 2-dichlorobutane was reported as a product. 6 In ...
