Intramolecular 1,3-dipolar Cycloaddition For Access To P,N-containing Heteropolycyclic

We develop two' efficient 1,3-Dipolar cycloaddition of the electron-deficient olefins(vinylphosphonate) with azomethine ylides and azometh imine. Firstly, we have synthesized many novel compounds with double functional groups (ethyl (2-formylphenyl)vinylphosphonate).Although the vinylphosphonate, which are electron-deficient olefins, have not yet been used as the dipolarophiles in 1,3-DCRs with azomethine ylides or azometh imine. There are just a few examples where vinylidenebisphosphonate undergoes cycloaddition reactions as a dipolarophile in 1,3-DCRs. We have developed a highly stereoselective method to obtain phosphadihydrocoumarin-fused pyrrolizidine derivatives and phosphadihydrocoumarin-fused- pyrazolone derivatives by catalyst-free intramolecular 1,3-DCRs. The reaction mechanism was proposed based on the experimental facts.The synthesis of heterocycles is of great importance because of their various applications as pharmaceutical, agricultural, and engineering materials. The clearly proposed mechanism is in line with the experimental data which can strongly prove that azomethine ylide is obtained in dehydration style, thus supplying some insight into the underlying-mechanisms of these cycloadditions. This methodology shows many notable features. such as broad substrates scope,high efficiency,and good selectivity. The targeted molecular are fully characterized by NMR, HRMS and IR. This approach will not only provide an efficient method for the first construction of phosphadihydrocoumarin scaffold but will also enrich the research areas of intramolecular 1,3-dipolar cycloaddition.