Procedures for isolating acetylenedicarbaldehyde (ADCA) 1 in the pure state, or for obtaining this unstable compound in diluted aprotic solutions (CH2C12, CCl4, toluene) are detailed. They are based on the acidolysis of its mono-[diEt]-acetal 2a with an excess of formic acid, followed by dehydration of residual acid into carbon monoxide with P205 in CH2C12 diluted solution. Under neutral conditions, ADCA reacts with dienes as ...
