排序方式: 共有121条查询结果,搜索用时 15 毫秒
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Dr. James I. Murray Nils J. Flodén Adriano Bauer Nico D. Fessner Daniel L. Dunklemann Dr. Opetoritse Bob-Egbe Prof. Henry S. Rzepa Prof. Thomas Bürgi Dr. Jeffery Richardson Prof. Alan C. Spivey 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(21):5854-5858
The first catalytic kinetic resolution by N-sulfonylation is described. 2-Substituted indolines are resolved (s=2.6–19) using an atropisomeric 4-dimethylaminopyridine-N-oxide (4-DMAP-N-oxide) organocatalyst. Use of 2-isopropyl-4-nitrophenylsulfonyl chloride is critical to the stereodiscrimination and enables facile deprotection of the sulfonamide products with thioglycolic acid. A qualitative model that accounts for the stereodiscrimination is proposed. 相似文献
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Dr. Yingguo Liu Pankaj Kumar Majhi Runjiang Song Dr. Chengli Mou Dr. Lin Hao Prof. Huifang Chai Prof. Zhichao Jin Prof. Yonggui Robin Chi 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(10):3887-3891
A catalytic dynamic kinetic resolution and asymmetric acylation reaction of hydroxyphthalides is developed. The reaction involves formation of a carbene catalyst derived chiral acyl azolium intermediate that effectively differentiates the two enantiomers of racemic hydroxyphthalides. The method allows quick access to enantiomerically enriched phthalidyl esters with proven applications in medicine. It also enables asymmetric modification of natural products and other functional molecules that contain acetal/ketal groups, such as corollosporine and fimbricalyxlactone C. 相似文献
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Hiroto Uno Dr. Nagender Punna Etsuko Tokunaga Dr. Motoo Shiro Prof. Norio Shibata 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(21):8264-8271
The two enantiomers of trifluoromethyl-benzo[c][1,5]oxazonines, (R)- 4 and (S)- 4 , can be selectively accessed with high enantiopurity by the Pd-catalyzed ring-expansion reaction of trifluoromethyl-benzo[d][1,3]oxazinones ( 1 ) with vinyl ethylene carbonates ( 3 ) using one antipode of a chiral ligand. Initially, the reaction proceeds by a double decarboxylative ring-expansion with kinetic resolution of 1 in the presence of a Pd-catalyst/chiral ligand to provide (R)- 4 with high enantiopurity. At the same time, the nonreactive antipode of 1 , (S)- 1 , which was recovered with an impeccable s factor of up to 713 and an ideal chemical yield, was transferred into the antipode of the products, (S)- 4 , with high enantiopurity by a second run of the Pd-catalyzed double decarboxylation reaction, but this time without any chiral auxiliary. Thus, both antipodes of the chiral trifluoromethyl heterocycles 4 can be obtained in excellent enantiopurity using only a single antipode of the chiral catalyst. 相似文献
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Sajesh P. Thomas Arnaud Grosjean Gavin R. Flematti Amir Karton Alexandre N. Sobolev Alison J. Edwards Ross O. Piltz Bo B. Iversen George A. Koutsantonis Mark A. Spackman 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(30):10361-10365
The observation of an unusual crystal habit in the common diuretic drug hydrochlorothiazide (HCT), and identification of its subtle conformational chirality, has stimulated a detailed investigation of its crystalline forms. Enantiomeric conformers of HCT resolve into an unusual structure of conjoined enantiomorphic twin crystals comprising enantiopure domains of opposite chirality. The purity of the domains and the chiral molecular conformation are confirmed by spatially revolved synchrotron micro‐XRD experiments and neutron diffraction, respectively. Macroscopic inversion twin symmetry observed between the crystal wings suggests a pseudoracemic structure that is not a solid solution or a layered crystal structure, but an unusual structural variant of conglomerates and racemic twins. Computed interaction energies for molecular pairs in the racemic and enantiopure polymorphs of HCT, and the observation of large opposing unit‐cell dipole moments for the enantiopure domains in these twin crystals, suggest a plausible crystal nucleation mechanism for this unusual crystal habit. 相似文献