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Relationships Between Step and Cumulative PMI and E-factors: Implications on Estimating Material Efficiency With Respect to Charting Synthesis Optimization Strategies

submitted on 26.06.2018, 20:12 and posted on 27.06.2018, 14:11 by John Andraos
This report describes mathematical relationships between step and cumulative process mass intensities (PMIs) for synthesis plans, and analogous parameters applied to Efactors. It is shown that both step E-factors and step PMIs are not additive for synthesis plans. It is also shown that a recursive calculation of cumulative PMIs from step PMIs is
a rapid method of determining overall PMIs for synthesis plans, though cumulative PMIs are not sufficiently informative as step PMIs or step E-factors to identify bottlenecks in
synthesis plans. Illustrations on the use of these metrics to track the material efficiency of published synthesis plans for the pharmaceutical, apixaban, are given as a template
example. Advantages and disadvantages of each metric are discussed. A general algorithm to select the most promising candidate synthesis plans considered at the design
stage for a given molecular target that most likely satisfy “green” material efficiency criteria is also presented.


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No conflict of interest.