Dehydrogenated Diels-Alder Reaction Of Isobutenyl Derivatives With 2,3 Dichloro-5,6 Dicyano-1,4 Bentonine

The Diels-Alder reaction is an organic chemical reaction between conjugated diene and substituted alkene, commonly termed the dienophile, to form a substituted cyclohexene system. As an important method to construct C-C bonds in organic synthesis, two new C-C bonds and four new stereocenters may be generated in a single step. Studies on the DA reaction have a long history, many remarkable endeavors have been made to develop various DA reactions. The cycloaddition products are widely used in agricultural chemicals, medicine and so on. However, one limitation of the reaction is that the diene component is usually unavailable and needs to be prepared. As a consequence, a dehydrogenative Diels-Alder (DHDA) reaction strategy has been emerged. This contains two variations:one is that a DA reaction takes place followed by a dehydrogenation; the other is that a dehydrogenative reaction takes place prior to a DA reaction. The latter one is more challenging and potential useful, because a C-H bond oxidation reaction is involved to prepare a diene in situ, and the newly generated stereocenters of the DA reaction product are remained. As this is an efficient method to realize DA reactions, it is high desirable to discover new variants of this type reaction. However, in recent reported DHDA reactions, metal catalysts and harsh reaction conditions are usually utilized.In this, the asymmetric catalytic DA and DHDA reactions have been reviewed. And an efficient, metal-free DHDA reaction of prenyl derivatives with DDQ is presented.