The hydrolysis of 2-methylbut-3-yn-2-yl carbamate gave 4,4-dimethyl-5-methylidene-1,3-dioxo-lan-2-one, whereas 2-methylbut-3-yn-2-ol was converted under similar conditions to 3-hydroxy-3-methylbutan-2-one. 2-[2-Amino(hydrazinyl)-6H-1,3,4-thiadiazin-5-yl]propan-2-yl carbamates were synthesized by reacting 4-bromo-2-methyl-3-oxobutan-2-yl carbamate with thiosemicarbazide and carbonothioic dihydrazide, respectively.