Formation of Aza-ortho-quinone Methides Under Room Temperature Conditions: Cs2CO3 Effect
| Autor: | Ashley A. Jaworski, Paul Ha-Yeon Cheong, M. Todd Hovey, Hannah V. Baker, Karl A. Scheidt, Ryne C. Johnston, Daniel M. Walden, Matthew P. Meyer |
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| Rok vydání: | 2017 |
| Předmět: |
chemistry.chemical_classification
Exothermic reaction Base (chemistry) 010405 organic chemistry Chemistry Organic Chemistry Enantioselective synthesis Salt (chemistry) 010402 general chemistry 01 natural sciences 0104 chemical sciences Quinone Catalysis Computational chemistry Organic chemistry Solubility |
| Zdroj: | The Journal of Organic Chemistry. 82:7183-7189 |
| ISSN: | 1520-6904 0022-3263 |
| Popis: | Since the first report of a facile, room temperature process to access aza-ortho-quinone methides (aoQMs) by Corey in 1999, this chemistry has remained dormant until our report of an enantioselective catalytic example in 2014. We report a theoretical and experimental study of the key to success behind these successful examples to enable broader exploitation of this useful intermediate. We have discovered that transformations involving the aoQM are remarkably facile with barriers 30 kcal/mol), precluding their formation under mild conditions. The use of Cs2CO3 as base is critical. It provides a thermodynamically and kinetically favorable means to form aoQMs, independent of the salt solubility and base strength. The exothermic formation of salt byproducts provides a driving force (average ΔG = −30.8 kcal/mol) compensating for the majority of the inherent unfavorable thermodynamics of aoQM formation. |
| Databáze: | OpenAIRE |
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