Despite the wide variety of chemistry conducted as part of drug discovery and development and the undoubted ingenuity of the chemists conducting the research, the majority of reactions still fall into a relatively small number of categories.
With this in mind, chemists in the industry have previously sought[i],[ii] to offer guidance that both encourages chemists to use greener reagents by first intent and provides a simple, easy-to-use reference for greener alternatives to be considered when reactions are repeated and/or scaled up.
More recently, the ACS GCI Pharmaceutical Roundtable has brought together contributions from multiple pharmaceutical companies to provide a more comprehensive set of reagent guides that you can find at http://www.reagentguides.com/.
Guides are freely available for 11 transformations: oxidation to aldehyde and ketones, nitro reduction, N-alkylation, O-dealkylation, ester deprotection, epoxidation, Boc deprotection, amide reduction, bromination, reductive amination, and metals removal.
Additional guides on Buchwald-Hartwig amination, iodination and chlorination are currently only available to members of the Pharmaceutical Roundtable, but are scheduled to be rolled out to a wider audience soon. The Roundtable will be developing and releasing additional guides over time.
A tutorial on the guides is available here: https://youtu.be/w05iq4VcPts
The ideal reagent will have all three characteristics and appear in the middle (green area) of the Venn diagram, whereas some reagents have one of the traits but none of the others or a mix of two but not the third.
Placement within the Venn diagram can change with many variables, including solvent, catalyst, treatment of wastes, etc.
Good green chemistry requires the chemist to look across a range of factors before making the best choice. With the inclusion of information like atom efficiency, ecotoxicology/toxicology profiles, safety issues, waste products, sustainable feedstocks and more, we hope these guides give promotion to some reagents as compared to others. A holistic approach is encouraged, however. For example, if a ‘greener’ reagent gives a much lower yield or requires multiple steps, the overall benefit may be outweighed (i.e., it may give rise to a higher footprint in the wider context) compared to an initially less ‘green’ reagent.
The American Chemical Society Green Chemistry Institute’s Pharmaceutical Roundtable (“the Roundtable”) has created this Reagent Guide to inform and guide users toward greener reagents for various chemical transformations. The Roundtable has used reasonable efforts in collecting, preparing and providing quality information and material, but does not warrant or guarantee the accuracy, completeness, adequacy or currency of the information contained in the Reagent Guide. By downloading, viewing and utilizing information from the Reagent Guide, visitors assume full responsibility for their own actions and any damages or liabilities that may result from the utilization of information obtained from the Reagent Guide. Should you have any questions or comments about the Reagent Guide or this disclaimer, please send an e-mail to firstname.lastname@example.org.
K. Alfonsi, J. Colberg, P. J. Dunn,* T. Fevig, S. Jennings, T. A. Johnson, H. P. Kleine, C. Knight, M. A. Nagy, D. A. Perry*, M. Stefaniak. Green Chem. 2008, 10, 31–36.
J. P. Adams, C. M. Alder, I. Andrews, A. M. Bullion, M. Campbell-Crawford, M. G. Darcy, J. D. Hayler, R. K. Henderson, C. A. Oare, I. Pendrak, A. M. Redman, L. E. Shuster, H. F. Sneddon,* M. D. Walker. Green Chem. 2013, 15, 1542-1549.
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