Theoretical Study on Photoisomerization of 2-Methylfuran to 3-Methylfuran

1 INTRODUCTION 2-Methylfuran belongs to the basic heteroaromatic compounds relevant to many fields of modern che- mistry, ranging from the study of natural products and biologically active substances to the develop- ment of building blocks for organic synthesis and conducting polymers1]. Since the photochemistry ofR-furan was gradually recognized in 1960s2～7], lots of interest has been aroused. Herein we only study one branch of photoche- mistry of R-furan: the isomerization of 2-methy…

Theoretical Study on Photoisomerization of 2-Methylfuran to 3-Methylfuran

In the present work, the photoisomerization of 2-methylfuran to 3-methylfuran is investigated with the complete active space SCF (CASSCF) molecular orbital method. Geometries of minima and transition states on the excited and ground states are fully optimized at the CAS level with a 6-31G* basis set. A multireference MP2 algorithm that has been implemented in Gaussian is used to correct the energetics for dynamic correlation. The topology and reaction funnels of the singlet, triplet (S0, T1, T2) and potential energy surfaces have been characterized along the reaction coordinates corresponding to the mechanism. The reaction proceeds via two diradical intermediates, one inter- mediate product and four transition states. The two diradical S1/T2 and T1/S0 energy surface crossing points are located along the reaction path and a T1/T2 conical intersection is also located. From this point the reaction soon returns to T1 surface. It is the most reasonable that the intersystem crossing from T1 to S0 takes place.