Ru/organo Relay Catalytic Tandem Reactions And Ptc Catalyzed Asymmetric[4+1]Cycloaddition Reaction

As one of the hot topics in the area of asymmetric catalysis,asymmetric metal and organo combined catalysis could take the advantages of both the catalysts,making lots of transformations that either of the individual catalysts can not realize alone possible.Combined catalysis generally includes:cooperative catalysis,relay catalysis and sequential catalysis.Cooperative catalysis and relay catalysis basically require the compatibility of different catalysts.Sequential catalysis describes a one-pot reaction containing two or more incompatible catalytic cycles,the catalysts or substrates need to be added in order so that the reaction could proceed smoothly.3-amino-3-alkyloxindoles have received increasing attention due to their frequent occurrence in bioactive compounds and natural products.We designed a Ru(II)/organo relay catalytic system to enable the three component reaction of 3-diazooxindoles,amines and nitroalkene leading to chiral 3-amino-3-alkyloxindoles.Moreover,on the basis of this metal/organo relay catalytic three-component reaction,a key intermediate for the synthesis of(-)-psychotrimine was accomplished in six steps with 25%overall yield,enhancind the efficiency of the synthesis of(-)-psychotrimine significantly.Optically active 3,3'-bisindole exists in different indole alkaloids,which have recevied more and more interests of chemists.Hence,we developed an asymmetric three-component reaction of indoles,3-diazooxindoles and diethyl azodicarboxylate by virtue of Ru(II)/organo relay catalysis,affording a series of chiral 3,3'-bisindole derivatives.We suggested a mechanism comprised of a metal-catalyzed C-H functionalization and asymmetric Michael addition process.Ortho-quinone methides(o-QMs)have been proven to be the active chemical structure of many important bioactive molecules like vitamins and antibiotics to produce therapeutic benefits in vivo.Phase-transfer catalysis is a practical strategy for organic synthesis,which features simple experimental operations,mild reaction conditions.We have developed an asymmetric phase-transfer catalyst catalyzed[4+1]cycloaddition of ortho-quinone methides and bromomalonate.A variety of dihydrobenzofurans can be obtained in high yields and excellent enantioselectivities.Importantly,the dihydrobenzofuran ring system is an important motif present in many nature products and pharmaceuticals.