1,3-Cyclobutandionderivate aus Keten

1,3-Cyclobutanedione derivatives from ketene The dimerisation of ketene leads mainly to the methylidene-β-lactone ‘Diketene’ 2c . It is shown, that also a small amount of the symmetrical dimer, 1,3-cyclobutadione 1c is produced, which under the reaction conditions is acetylated to 3-acetoxycyclo-butenone (5) .