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Study on the Catalytic Behavior of Bifunctional Hydrogen‐Bonding Catalysts Guided by Free Energy Relationship Analysis of Steric Parameters
Author(s) -
Yang Chen,
Wang Jie,
Liu Yang,
Ni Xiang,
Li Xin,
Cheng JinPei
Publication year - 2017
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.201605666
Subject(s) - bifunctional , steric effects , catalysis , chemistry , hydrogen bond , thiourea , cyclohexane , cinchona , organocatalysis , diamine , organic chemistry , combinatorial chemistry , computational chemistry , enantioselective synthesis , molecule
Free energy relationship (FER) studies to correlate steric parameters with the enantiocatalytic performance of bifunctional tertiary‐amine hydrogen‐bonding catalysts, including ( S , S )‐cyclohexane‐1,2‐diamine‐derived thioureas, Cinchona alkaloid derived thioureas, and ( S , S )‐cyclohexane‐1,2‐diamine‐derived squaramides, in Michael reactions revealed that the reactions are much favored by catalysts with less bulky N‐substituents. The observed FERs are independent of the chiral scaffold and hydrogen‐bond donor, and deepen the understanding of current bifunctional hydrogen‐bonding catalysts. Moreover, DFT calculations were performed to interpret the observed high reactivities of thioureas with less bulky substituents. In particular, the computations demonstrated the advantage of a benzyl thiourea catalyst, in which an extra CH ⋅⋅⋅ π interaction between catalyst and substrate is the key factor.