Information theory description of synthetic strategies. A new similarity index

Search for complexity generating chemical transformations by combining connectivity analysis and cascade transformation patterns

Retrosynthetic analysis involved in a backward search for strategic disconnections is still the most powerful strategy, recently advanced by topology-based complexity estimation, for discovering the shortest sequences of transformations and chemical synthesis planning. Therein, we propose an alternative strategy that combines backward and forward search embodied within a mathematical model of generating chemical transformations. The backward reasoning involves a new concept of the strategic bond tree for alternative multibond disconnections of a target molecule. In the forward direction, each combination of the resulted structural fragments is examined for reconstruction of the target structure by means of biomimetic transformation patterns that describe one-pot multibond forming reactions. The algorithm has been implemented into the CSB system, and its performance is illustrated by examples of published complex molecule syntheses for comparison and analysis. This paper describes the strategy for discovering the shortest synthetic pathways based on the multibond forming cascade transformations for application in synthesis design and generating synthetically accessible product libraries.