Abstract
It has been possible to use the computer-assisted synthesis design system such as AIPHOS and EROS in order to create new synthetic routes of target compounds. However, these systems produce several synthetic routes without giving information which route should be applied first in experiments. It is common knowledge that transition states are keys for how to estimate easiness of chemical reactions and computational chemistry delivers that answer. However, organic chemists have to take great effort to use molecular orbital calculations and to obtain transition state geometry. A system, which makes it possible to treat transition states even by organic chemists, should be very useful. In the present study, we intended to develop a new program which offers organic chemists to search transition states easily and to analyze chemical reactions in detail. The system includes three standard methods, which are the minimum energy path, the saddle and the contour methods. The program was also installed the substitution method, which adds a cyclic or an acyclic substituent to transition state structures previously obtained. It was confirmed that this method is very useful to find transition states of chemical reactions.
