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The H‐Bond activation mechanism and enantioselectivity in stepwise conjugate amine addition promoted by hydroxyl‐thiourea catalyst
Author(s) -
Lu Nan,
Chen Dezhan,
Mi Shizhen,
Zhang Guiqiu,
Zhang Honghong
Publication year - 2011
Publication title -
international journal of quantum chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.484
H-Index - 105
eISSN - 1097-461X
pISSN - 0020-7608
DOI - 10.1002/qua.22513
Subject(s) - chemistry , oniom , thiourea , catalysis , enantioselective synthesis , density functional theory , medicinal chemistry , pyrazole , amine gas treating , computational chemistry , organic chemistry
The H‐bond activation mechanism and enantioselectivity of hydroxyl‐thiourea catalyst in conjugate amine addition of O ‐benzyl hydroxylamine to pyrazole crotonate is investigated using density functional theory (DFT) calculations. Two competing activation models are explored in detail. CN bond formation is stepwise in both of the two models. The enantioselective (S)‐channel is more favorable than (R)‐channel via the calculated barriers. The enantioselectivity originated from si face preferable than re face can be attributed to the H‐bonded network provided by thiourea and hydroxyl groups in rate‐determining step. The enantiomeric excess (ee) values predicted through ONIOM calculations are in line with the experiment. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2011