Structural Effects in the Reactions of Diazoalkanes with 2,3-Dichloro-5,6-dicyanobenzoquinone

Article abstract of DOI:10.1246/bcsj.59.3865

2,3-Dichloro-5,6-dicyanobenzoquinone(DDQ) reacted with diazoethane to give stereoisomeric bicyclic diones (3, isomer ratio=3.4) arising from dipolar addition to the C=C bond of DDQ.DDQ reacted with phenyldiazomethane to afford also stereoisomeric bicyclic diones (7) in the ratio of 5:1, together with stilbenes (8).On the other hand, DDQ gave the (ethenyloxy)benzene derivative (14) with 1-phenyldiazoethane.The formation of 8 and 14 was interpreted by considering the participation of 1:1 betaines resulting from addition to the C=C bond.The added methanol captures the betaines, thus giving rise to dimethyl acetals of benzaldehyde and acetophenone, along with 2,3-dichloro-5,6-dicyanohydroquinine.These reactivities of DDQ were discussed in comparison with those of chloranil.