| Transition-metal-catalyzed cross-coupling reactions have been established as anindispensable tool for the construction of carbon-carbon and carbon-heteroatom duringmodern synthetic organic chemistry. In almost50years, the great developments have beenmade in the reaction mechanism and utilizations of a Palladium-catalyzed cross-couplingreaction. Meanwhile, metal-carbene chemistry plays a significant role in organometallicchemistry and organic synthesis. Nevertheless, during a long period of time, these reactionshave evolved respectively, with essentially no integration or overlap.The first Palladium-catalyzed cross-coupling reaction between diazo compounds andbenzyl halides was reported in2001, and the key process of a catalytic cross-couplinginvolving a Pd-carbene migratory insertion has triggered renewed interest. N-tosylhydrazones,which can be readily prepared from carbonyl compounds, are useful synthetic intermediateswhich have been applied in organic chemistry for nearly60years, and it have been turned outto be useful for the in situ generation of diazo compounds via Bamford-Stevens reaction. Withthe recent discovery of a palladium-catalyzed cross-coupling involving N-tosylhydrazones, ithas become a new method to construct new carbon-carbon and carbon-heteroatom.Based on our group’s recent research achievements in a palladium-catalyzed oxidation ofunsaturated hydrocarbons using molecular oxygen and a cross-coupling involvingN-tosylhydrazones, a facile and highly regioselective palladium-catalyzed aerobic oxidativecoupling of N-tosylhydrazones providing efficient access to2,3-disubstituted-1,3-butadieneshas been developed. This process features readily available starting materials and mildreaction conditions. Further transformations of the obtained dibranched conjugated1,3-dienes,via Diels-Alder reactions and indene synthesis, are also demonstrated, which reveal their greatpotential for synthetic utility. |
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