Chirality of the trisubstituted nitrogen center - XRD, dynamic NMR, and DFT investigation of 1,2-dihydrobenzo[e][1,2,4]triazine derivatives

被引:4
|
作者
Kaszynski, Piotr [1 ,2 ,3 ]
Klys, Arkadiusz [2 ]
Domagala, Slawomir [4 ]
Wozniak, Krzysztof [4 ]
机构
[1] Polish Acad Sci, Ctr Mol & Macromol Studies, Sienkiewicza 112, PL-90363 Lodz, Poland
[2] Univ Lodz, Dept Chem, Tamka 12, PL-91403 Lodz, Poland
[3] Middle Tennessee State Univ, Dept Chem, Murfreesboro, TN 37132 USA
[4] Univ Warsaw, Dept Chem, Pasteura 5, PL-02089 Warsaw, Poland
关键词
Chirality; Dynamic NMR; Heterocyclic chemistry; Single crystal XRD; DFT calculations; CONFORMATIONAL RATE-PROCESSES; ASYMMETRIC NITROGEN; CONFIGURATIONAL STABILITY; MOLECULAR-STRUCTURE; HINDERED INVERSION; GEMINAL SYSTEMS; N BOND; HYDRAZINES; RESOLUTION; BARRIERS;
D O I
10.1016/j.tet.2017.05.032
中图分类号
O62 [有机化学];
学科分类号
070303 ; 081704 ;
摘要
Molecular structures of two 1-aryl-2-benzyloxycarbonyl-1,2-dihydrobenzo[e][1,2,4]triazines 1 were established by single crystal XRD and compared to those of 4-benzyloxycarbonyl (2) and 4-benzyl (4) analogues. The structures revealed a highly pyramidalized asymmetric N(1) center stabilized by steric interactions in 1, but not in 2 and 3. Activation parameters for enantiomer interconversion were obtained by DNMR methods in C6D5Cl: Delta H-double dagger = 18.1(1) kcal mol(-1), Delta S-double dagger= -0.6(1) cal mol(-1) K-1 for Ar = Ph (1a) and Delta H-double dagger = 18.6(4) kcal mol(-1), Delta S-double dagger = 5.2(6) cal mol(-1) K-1 for Ar = 2-anisyl (1b). DFT computational investigation of the origin of the interconversion barrier on model compounds revealed steric destabilization of the inversion TS. (C) 2017 Elsevier Ltd. All rights reserved.
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页码:3823 / 3830
页数:8
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