An experimental and theoretical approach to synthesis of novel indolizine type heterocycles

Abstract

Indolizine derivatives are interesting due to their anti-inflammatory and antioxidant properties as well astheir known fluorescent properties. Theoretical studies supported by the experimental evidences can shedlight on the fundamental understanding of the versatility of the synthetic approaches. Herein, 1,3-dipolarcycloaddition reactions of three pyridinium ylides with seven dipolarophiles was studied theoretically atFMO level (PM3-RHF calculations) for the first time. The theoretical studies suggested a more probablereaction of pyridinium ylides with the dipolarophiles such as vinyl acetate and vinylene carbonate.However, the ylides have reacted only with dimethyl acetylenedicarboxylate and diethyl acetylenedicarboxylate, indicative of the effect of other reaction parameters (e.g. solvent, temperature etc.).Experimentally, only six indolizine heterocycles, two of which are not reported previously (18 and 19),were synthesized and theoretical predictions were further compared with experimental findings. Thestructural analysis of synthesized indolizine compounds was performed by 1H NMR, FTIR, GC-MS andelemental analysis.