Synthesis of substituted cyclobutenediones from 3-ethenyl-4-methoxy-cyclobutene-1,2-dione

Article abstract of DOI:10.1016/S0040-4039(00)92025-2

The synthesis of 3-ethenyl-4-methoxycyclobutene-1,2-dione from dimethyl-squarate is described. This compound was observed to undergo facile 1,6-addition of both carbon and non-carbon nucleophiles to the 3-alkenyl group. Thus, it serves as a versatile starting material for the synthesis of a variety of substituted cyclobutenediones which are convenient starting materials to a variety of other ring systems.