Study On Thermochemical And Photochemical Reactions Of 1,4-Dihydropyridines

1,4-dihydropyridine is widely used as a calcium channel inhibitor in the treatment of hypertension and cardiovascular diseases.It’s used as a substrates to participate in thermochemical and photochemical reactions for it’s active chemical properties by it’s 6πelectron system with two carbon-carbon double bonds.Especially,the photocyclization products show better biological pharmacological activities,such as anti-HIV and anti-tumor.The thermochemical reactions of 1,4-dihydropyridines mainly contain redox and aromatization.The photochemical reactions mainly invove cyclization,photooxidation and rearrangement.By reviewing the literature of thermochemical and photochemical reaction,the aromatization and redox reaction of1,4-dihydropyridine and the photocyclization have been reported.The studies of the thermocyclization and photocyclization of asymmetric 1,4-dihydropyridine has not been reported yet.Therefore,the study of thermocyclization and photocyclization of1,4-dihydropyridines will provide theoretical and experimental basis for its more applications in the future.（1）The study on the thermochemical reaction of 1,4-dihydropyridines.The ethyl1,4-diaryl-1,4-dihydropyridine-3-carboxylate was used as the substrate to study the thermochemical reaction of 1,4-dihydropyridines with 2,2,6,6-tetramethylpiperidine-1-oxyl（TEMPO）as radical initiator.The effects of the TEMPO on the reaction were investingated in details.The reaction products was separated and identified to be ethyl3-phenyl-1-aryl-1H-pyrrole-2-carboxylate.The mechanism was speculated by quantum chemical calculation.The result showed that the 1,4-dihydropyridines didn’t react the cyclization but the ring contraction affected by TEMPO.The products were confirmed by ¹H NMR,¹³C NMR,MS and X-ray diffraction.（2）The study on the photochemical reaction of 1,4-dihydropyridines.Racemic and R-configured 1,4-phenyl-1,4-dihydropyridine-3-formamide was used as the substrate to investigate the photocyclization.The effects of the wavelength of the light and the substrate structure（chiral effect and steric effect）on the photocyclization were studied.The separation and identification of he photochemical products interpreted the effects of the wavelength and the substrate structures on the reaction.The results showed that the chirality of the substrate have the effect on the products of the photoaddition.The chirality can promote the reaction to giving a single chiral product,but the spatial effect of the 3-substituents has no obvious effect on the reaction.Six novel photochemical products were obtained to be two3,9-diazatetraasteranes,two 3,6-diazatetraasteranes,one 6,12-diazaterakishomo-cubane and one tetrahydrocyclopentane.The products were confirmed by ¹H NMR,¹³C NMR,MS and X-ray diffraction.