Study On The Synthesis Of New Heterocyclic Compounds Involving Zwitterion Induced From DMAD

Due to the atom economy, convergent character, high yields and diversity, multi-component reactions (MCRs) have become a powerful method for the synthesis of small-molecule libraries. This approach offers significant advantages over classical stepwise approaches, so MCRs are widely used in discovery of medicine, agricultural chemistry and synthesis of natural products.Zwitterionic species often come from the addition of nucleophiles to activated alkynes like dimethyl acetylenedicarboxylate (DMAD). A variety of nucleophiles such as triphenyl phosphine (PPh3), pyridine, tertiary amine, dimethyl sulfoxide etc.has been known to generate zwitterionic species by this pathway.In this paper, one-pot multi-component synthetic method combined with zwitterionic species was uesd for generating the target heterocyclic compounds.In the first chapter, dimethyl 2-benzoylfumarate, which was an important intermediate, was synthesized from arylaldehydes with dimethyl acetylene- dicarboxylate (DMAD), catalyzed by pyridine. Then it reacted with phenylhydrazine in situ. In this way, six dimethyl 3-(aryl)-1-phenyl-4,5-dihydro-1H-pyrazole-4,5- dicarboxylates 1a-1f were synthesized through one-pot four-component reaction.In the second chapter, eleven dimethyl 2-(aryl)-2,13b-dihydro-[1,3]oxazino [3,2-f]phenanthridine-3,4-dicarboxylate derivatives 2a-2i′was synthesized by the zwitterion generated by the addition of nucleophiles phenanthridine to activated alkynes dimethyl acetylenedicarboxylate (DMAD) with substituted benzaldehyde through one-pot three-component reaction. Different solvents and the reaction temperature for this MCR were investigated. Using CH2Cl2 as solvent at room temperature were deemed to the optimum reaction condition.In the third chapter, two single-crystals (1b, 2c) were cultured and the structure of the compounds were ultimately characterized byΧ-ray single-crystal diffraction analysis.The structures of all the synthesized compounds were characterized by IR, 1H NMR, 13C NMR, MS or HRMS. Two single-crystals were cultured and the structure of the unknown compounds could be confirmed conveniently byΧ-ray single-crystal diffraction analysis.