Quaternary ammonium salts with a 1,1-dimethylbut-2-yne-1,4-diyl common group react with aqueous alkali with intermediate formation of 1,2- rather than 1,4-cleavage products. When both nitrogen atoms bear allylic groups, rearrangement-cleavage-substitution occurs to give methyl isopropyl ketones. Salts with two 3-methylbut-2-en-1-yl groups cleave isoprene.
Quaternary ammonium salts with a 1,1-dimethylbut-2-yne-1,4-diyl common group react with aqueous alkali with intermediate formation of 1,2- rather than 1,4-cleavage products. When both nitrogen atoms bear allylic groups, rearrangement-cleavage-substitution occurs to give methyl isopropyl ketones. Salts with two 3-methylbut-2-en-1-yl groups cleave isoprene.