Enhanced recognition and encoding of stereoconfiguration by InChI tools

Enhanced recognition and encoding of stereoconfiguration by InChI tools

Description
InChI and InChIKey already are very useful for identification and search of substances in various sources of chemical information. While InChI tools resolve most aspects of constitutional isomerism, especially for organic substances, some types of stereoisomerism and representations of stereoconfiguration are not recognized. The most significant examples include atropisomerism and very common representation of carbohydrates in Haworth and chair forms. Unsupported stereoisomerism types results in the inability to distinguish specific isomers and the incorrect treatment of some representations results in incomplete or even wrong InChI identifiers.

Another distinct problem is the unsupported MOLFile V3000 enhanced stereo information that is currently used to represent mixtures of stereoisomers for industrial chemicals. Such structures are currently incorrectly interpreted by InChI tools as representing single stereoisomers.

Other problems that the project intends to address include nontetrahedral stereoconfigurations often encountered in coordination compounds but existing for organic compounds as well and unrecognized configurations for several specific cases including pyramidal arrangements and cumulenes with more than three cumulated bonds. The development of the principles for recognition and encoding of configurations for coordination structures will take into account the results of InChI for organometallics project 2009-040-2-800.