< Synthesis Design

To search for available starting materials, similarity searches, substructure searches, and some classical retrieval methods such as full structure search, name search, empirical formula search, etc. have been integrated into the system. All searches can be applied to a number of catalogs of available fine chemicals (e.g. Fluka). In addition, compound libraries such as in-house catalogs can easily be integrated.
Similarity searches are essential methods in WODCA to be used to generate a relationship between the synthesis target or precursors and available starting materials. Similarity searches in WODCA are performed on the basis of similarity criteria that are either based on the presence of substructures or on generalized reactions.
Each criterion contains a rule for the transformation of the query structure (target, precursor). The transformed query is then compared with all transformed molecules in the database (the transformed molecules in the database had been computed and stored during the implementation of the catalog). If both the transformed query and the transformed catalog compound are identical, then the database structure is suggested as suitable starting material to the user. The principle of similarity searches is illustrated by the criterion ‘maximum oxidation state’ in the following figure:
principle of similarity searches The comparison for identity of chemical structures is performed on the basis of a hashcode algorithm [1]. Hashcodes are unique integer numbers which can be calculated for each chemical structure within the WODCA system.


[1] Ihlenfeldt, W. D.; Gasteiger, J. "Hashcodes for the identification and classification of molecular structure elements" J. Comput. Chem. 1994, 15, 793-813.