Cyclization And Radical Reaction Based On N,N-Dimethylenaminones

As one of the essential member of the enaminone family,the reactions of N,N-dimethylenaminone compounds,particularly involving the cyclization reactions and free radical reactions have special meaning for organic synthesis.Though it was widely accepted that they could apply to the construction of heterocyclic backbones,synthesis of natural products,and research of new drugs,the transition and noble metals can lead to high costs and transitional metal residues and other issues and in the meantime the free radical reactions based on N,N-dimethylenaminone were rare.Therefore,utilizing transition-free metals to promote the cyclization reaction of N,N-dimethylenaminone compounds plays a key role in constructing heterocyclic compounds.Based on the N,N-dimethylenaminone,chemoselective synthesis of quinolone,spirooxindoles and 3-furaldehyde skeletons compounds in this article via the cyclization reaction.and via the radical reaction synthesis of??ketophosphonates which protocol for C_sp3-P bond formation by oxidative C_sp2-C_sp2 bond cleavage in one step.And the two main aspects of this paper are shown:1.Cyclization reactions based on N,N-dimethylenthanoneSynthesis of quinolines:on the base of N,N-dimethylenthanone and o-aminoacetophenone,promoted by the p-TSA polysubstituted quinolines and N-aryl-enaminones was synthetized via[4+2]cyclization reaction which temperature and amount of catalyst synergistic control?scheme 1?.Scheme 1 chemoselective synthesis of N-aryl-enaminones and 3-aroyl quinolinesA novel synthetic strategy for the construction of quinoline-4-carboxylates has been developed via two types of elimination-esterification cascade cyclization reaction,namelyBi?OTf?₃-catalyzedN-aryl-enaminone-basedandTMSCl-promoted N,N-dimethylenaminone-based reaction with isatins.Compared with the known cascade cyclizations of enaminones and isatins,two transformations represent an advancement in enaminone chemistry with a site-selective and straightforward approach toward 3,4-disubstituted quinoline-4-carboxylates?scheme 2?.Scheme 2 two types of elimination-esterification cascade cyclization reactionSynthesis of spirooxindoles:TMSCl–promoted cascade cyclization of isatins,N,N-dimethylenaminones and amines access to spirooxindoles.Remarkably,bis-enaminone was the key intermediate of the unexpected fourmolecular cascade cyclization?Scheme 3?.Scheme 3 four-molecular cascade cyclization for the synthesis of spirooxindolesSynthesis of 4-spiro-1,4-DHP derivatives via one-pot three-component reaction of isatins,N,N-dimethylenaminones with ammonium acetate in Et OH/Water solution promoted by acetic acid.this[1+2+1+2]cyclisation procedure has advantages as it is more environmentally friendly,has easier operational simplicity,and requires milder reaction conditions?Scheme 4?.Scheme 4 Synthesis of 4-spiro-1,4-DHP derivativesSynthesis of 3-furfural compounds:A simple and efficient synthesis of3-furfural derivatives based on N,N-dimethylenthanone via the[3+2]cyclization reaction.Copper-promotion one-pot single-molecule and two-components reaction of N,N-dimethylenthanone,This method has advantages of good atomic economy and wide tolerance of the substrate?Scheme 5?.Scheme 5 Synthesis of 3-Furodehydes via[3+2]cyclization2.Free radical reaction based on N,N-dimethylenaminoneMn?OAc?₃-promoted oxidative phosphonylation of N,N-dimethylenaminones with H-phosphonates,involving a chemo-and regioselective C_sp2-C_sp2 bond cleavage and C_sp3-P bond formation in one step,provided successfully functionalized?-ketophosphonates under mild reaction conditions.Oxidative C_sp3-H/P-H cross-coupling reactions via C_sp3-C?C=O?bond cleavage.This novel method proceeds in good to excellent yields,shows operational simplicity,broad substrate scope?Scheme 6?.Scheme 6 synthesis of ?-ketophosphonates via radical reactions...