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4001500 
Journal Article 
Theoretical studies of the asymmetric binary-acid-catalyzed tert-aminocyclization reaction: origins of the C(sp 3)-H activation and stereoselectivity 
Zhang, L; Chen, L; Lv, J; Cheng, JP; Luo, S 
2012 
Yes 
Chemistry - An Asian Journal
ISSN: 1861-4728
EISSN: 1861-471X 
7 
11 
2569-2576 
English 
22965688 
A mechanistic study of the tert-aminocyclization reaction was performed by using DFT calculations and labeling experiments. The results showed that the reaction proceeded through a rate-limiting-, stereospecific-, and suprafacial 1,5-H-transfer pathway, followed by a barrier-less C-C bond formation. The mode of stereocontrol for facial selection could be ruled out owing to the high activation energy of C-N bond rotation. The intrinsic feature of this Lewis acid activation was found to be the activation of the LUMO, as well as an intermediate-stabilization effect. The catalytically active species was believed to be a 1:1 complex of phosphoric acid and MgCl(2), which was stabilized by a H⋅⋅⋅Cl hydrogen bond. The chiral catalytic complex selectively recognizes and activates one of the two helical conformations of substrate A, required for 1,5-suprafacial H-transfer, which dictates the stereoselectivity of the forming products.