| Autor: |
Amy Boylan, Thien S. Nguyen, Brian J. Lundy, Jian-Yuan Li, Ravikrishna Vallakati, Sasha Sundstrom, Jeremy A. May |
| Jazyk: |
angličtina |
| Rok vydání: |
2021 |
| Předmět: |
|
| Zdroj: |
Molecules, Vol 26, Iss 6, p 1615 (2021) |
| Druh dokumentu: |
article |
| ISSN: |
1420-3049 |
| DOI: |
10.3390/molecules26061615 |
| Popis: |
Two key factors bear on reaction rates for the conjugate addition of alkenyl boronic acids to heteroaryl-appended enones: the proximity of inductively electron-withdrawing heteroatoms to the site of bond formation and the resonance contribution of available heteroatom lone pairs to stabilize the developing positive charge at the enone β-position. For the former, the closer the heteroatom is to the enone β-carbon, the faster the reaction. For the latter, greater resonance stabilization of the benzylic cationic charge accelerates the reaction. Thus, reaction rates are increased by the closer proximity of inductive electron-withdrawing elements, but if resonance effects are involved, then increased rates are observed with electron-donating ability. Evidence for these trends in isomeric substrates is presented, and the application of these insights has allowed for reaction conditions that provide improved reactivity with previously problematic substrates. |
| Databáze: |
Directory of Open Access Journals |
| Externí odkaz: |
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