Ruthenium- and Copper-Catalyzed Propargylic Substitution Reactions of Propargylic Alcohol Derivatives with Hydrazones

Ruthenium- and copper-catalyzed propargylic substitution reactions of propargylic alcohol derivatives with N-monosubstituted hydrazones as ambident nucleophiles are achieved in which N-monosubstituted hydrazones exhibit impressive different reactivities depending on different catalytic systems, behaving as carbon-centered nucleophiles to give the corresponding propargylic alkylated products in ruthenium catalysis, or as nitrogen-centered nucleophiles to afford the corresponding propargylic aminated products in copper catalysis. DFT calculations were carried out to investigate the detailed reaction pathways of these two systems. Further transformation of propargylic substituted products affords the corresponding multisubstituted pyrazoles as cyclization products in good to high yields.

Automated summary

In this study, propargylic substitution reactions using ruthenium and copper catalysis with N-monosubstituted hydrazones as ambident nucleophiles were investigated. It was found that N-monosubstituted hydrazones exhibited different reactivities depending on the catalytic system, resulting in either propargylic alkylated or aminated products. DFT calculations were used to study the reaction pathways and further transformation of the products yielded multisubstituted pyrazoles in good to high yields.