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- Title
Study of Ground State Interactions of Enantiopure Chiral Quaternary Ammonium Salts and Amides, Nitroalkanes, Nitroalkenes, Esters, Heterocycles, Ketones and Fluoroamides.
- Authors
Bencivenni, Grazia; Salazar Illera, Diana; Moccia, Maria; Houk, K. N.; Izzo, Joseph A.; Novacek, Johanna; Grieco, Paolo; Vetticatt, Mathew J.; Waser, Mario; Adamo, Mauro F. A.
- Abstract
Chiral phase‐transfer catalysis provides high level of enantiocontrol, however no experimental data showed the interaction of catalysts and substrates. 1H NMR titration was carried out on Cinchona and Maruoka ammonium bromides vs. nitro, carbonyl, heterocycles, and N−F containing compounds. It was found that neutral organic species and quaternary ammonium salts interacted via an ensemble of catalyst +N−C−H and (sp2)C−H, specific for each substrate studied. The correspondent BArF salts interacted with carbonyls via a diverse set of +N−C−H and (sp2)C−H compared to bromides. This data suggests that BArF ammonium salts may display a different enantioselectivity profile. Although not providing quantitative data for the affinity constants, the data reported proofs that chiral ammonium salts coordinate with substrates, prior to transition state, through specific C−H positions in their structures, providing a new rational to rationalize the origin of enantioselectivity in their catalyses.
- Subjects
AMMONIUM salts; QUATERNARY ammonium salts; PHASE-transfer catalysis; AMIDES; NITROALKANES; KETONES; NITROALKENES
- Publication
Chemistry - A European Journal, 2021, Vol 27, Issue 44, p11352
- ISSN
0947-6539
- Publication type
Article
- DOI
10.1002/chem.202100908