Synthesis of 1-methyl-4-alkyl-1,3-diacetylenes. Prototropic rearrangement in 1-alkyl-1,3-diacetylenes

Treatment of 2-methyl-2-hydroxy-6-alkyl-3,5-diacetylenes with powdered NaOH was used for the synthesis of terminal 1-alkyl-1,3-butadiynes that can be isolated (54–97%) or used in situ. In an attempt to increase the yields of some of the obtained products, different experimental conditions were studied and we found that by using CTAB as a catalyst, a prototropic rearrangement was promoted to afford the 1-methyl-4-alkyl-1,3-diacetylenes in the 62–94% yield range.