FURTHER DEVELOPMENT OF A REACTION GENERATOR IN THE SOPHIA SYSTEM FOR ORGANIC-REACTION PREDICTION - KNOWLEDGE-GUIDED ADDITION OF SUITABLE ATOMS AND OR ATOMIC GROUPS TO PRODUCT SKELETON/

A reaction generator-in SOPHIA (system for organic reaction prediction by heuristic approach) generates all possible product structures by r econnections of free bonds obtained by cutting all bonds of a reaction site which is automatically perceived in the input reactantt structur e and additions of atoms and/or atomic groups (AAG) to the free bonds. The reaction generator has been extended to automatically recognize a nd add suitable AAG for suitable free bonds by utilizing knowledge bas e derived from a reaction database. Contents of the knowledge base are structural information of AAG and structural characteristics of sites and their environments to which the AAG are added during reactions in a reaction database. The reaction generator considers reaction condit ions to recognize suitable AAG for suitable free bonds by utilizing re action condition groups obtained by classification based on word combi nations of reaction condition descriptions in a reaction database. SOP HIA also has been extended to employ the reaction condition groups for interpretation of reaction conditions entered by the user and to cons ider the reaction conditions in reaction prediction procedures. This p aper describes the contents and structure of the knowledge base, the r eaction condition classification, and implementation of the reaction p rediction using these results.