Case, a computer model of the structure elucidation process

Abstract

CASE (computer-assisted structure elucidation) is an outgrowth of an effort to develop a computer model of structure elucidation. The current capability of CASE in assembling molecules compatible with the structural information entered and in providing interactive user access to the file of assembled molecules is discussed. Of central importance to the effective application of the system to real-world structure problems are the design of the communication link that accepts structural-constraints information and the efficiency of molecule assembly. The chemist—computer interface is designed to accommodate the great and ever-increasing diversity of available structural information. Molecule assembly proceeds by stepwise bond making. Efficient program execution requires the evaluation of each node in the tree against the structural constraints imposed. However, program response time can be improved by heuristic implementation of constraints during molecule assembly and prospective pruning of unproductive branches from the search space as early as possible. CASE must perceive the significance, not only of the individual constraints themselves, but of their interaction as well. A newly added program to edit, analyze, and peruse the constructed list of molecules provides invaluable guidance in the design of the new experiments required to limit further the number of valid candidates. Such fine tuning of the CASE program enhances its utility and ensures that no plausible structures escape consideration.