Palladium-catalysed Asymmetric Annulations Of Vinylethylene Carbonates

In recent years,heterocyclic compounds have gradually become a research focus of scientists around the world due to their significant biological activity.In the palladium catalyzed decarboxylation asymmetric allylation,the control of stereoselectivity with chiral ligands is a crucial step.Reported herein is the divergent syntheses of [4,4] and [4,5] spiro-heterocycles under Lewis-acid-assisted palladium catalysis.In particular,When the Pd/BINAP and Lewis acid synergistic catalysis system,a series of [4.4] pyrrolidine spiro ring skeleton compounds can be stereoselective constructed efficiently and concisely.Obtain medium to good yields and excellent stereoselectivity control(dr >20:1,up to >99% ee).For the Pd/BINAP and Lewis base synergistic catalytic system,it provides an effective method for constructing [4.5]pyrrolidine spirocyclic skeleton compounds,which can achieve medium to good yields.This method uses a simple procedure and commercially available catalysts,and delivers both classes of spiro-heterocycles,bearing three contiguous stereocenters,in high yield and uniformly excellent stereoselectivity and diastereoselectivity.This research group investigated the palladium-catalyzed [3+2] cyclization of allyl cyclic carbonate with 5-alkenyl thiazolone with highly chemo-and diastereoselective.The previously inert aza-thioester moiety on the thiazolone substrates is reacted selectively with the zwitterionic π-allylpalladium species.A variety of amide monothioacetals(AMTA)with two quaternary stereocenters are facilely synthesized,but failed to achieve chiral synthesis.Then that metal rhodium is use for catalyzing the diazo compound to form the metal carbene to insert the C-S bond of the amide monothioacetals with high diastereoselectivity,and further adde a spirocyclic quaternary carbon center.The synthetic method has that advantage of short reaction time,high reaction activity,mild condition,simple post-treatment,and excellent yield.