5231-86-7

1-Methoxy-2-hydroxycyclobutene-3,4-dione 2-Hydroxy-1-methoxycyclobutene-3,4-dione 3-Hydroxy-4-methoxy-3-cyclobutene-1,2-dione 3-Cyclobutene-1,2-dione, 3-hydroxy-4-methoxy-