Theoretical studies of proton transfer reactions in 1-methylindene

The base-catalysed 1,3-proton transfer reactions in 1-methylindene have been studied theoretically in polar (water) and unpolar (cyclohexane) solvents, respectively, for two different choices of bases, namely ammonia and trimethylamine (TMA), using the SM2, SM3 and SM4 models of Cramer and Truhlar. The calculations confirm earlier predictions that the proton moves relatively freely over the indene ring once it is abstracted from its original location by the base, while correcting some methodological shortcomings of the earlier studies. A discussion is given of the kinetic consequences of the structures and relative energies of the relevant transition states and intermediates for the different cases.