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Study of Ground State Interactions of Enantiopure Chiral Quaternary Ammonium Salts and Amides, Nitroalkanes, Nitroalkenes, Esters, Heterocycles, Ketones and Fluoroamides
Author(s) -
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.
Publication year - 2021
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.202100908
Subject(s) - enantiopure drug , chemistry , ammonium , catalysis , salt (chemistry) , titration , cinchona , substrate (aquarium) , transition state , nitro , enantioselective synthesis , medicinal chemistry , organic chemistry , oceanography , geology , alkyl
Abstract Chiral phase‐transfer catalysis provides high level of enantiocontrol, however no experimental data showed the interaction of catalysts and substrates. 1 H 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 (sp 2 )C−H, specific for each substrate studied. The correspondent BArF salts interacted with carbonyls via a diverse set of + N−C−H and (sp 2 )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.