Subsequently,
D encounters a stepwise b-H elimination and metalehydrogen
exchange to form dihydropyrazole F. Assisted by the
oxidant, dehydrogenation occurs spontaneously and leads to the final product5a. Inthis reaction, the activation of imine and the existenceof
oxidant are essential. Zn(OTf)2 could lower the activation energy and promoted the electron flow possiblewhile DTBP could assist the
dehydrogenation to occur and push the reaction forward..