Synthesis and antitubercular activity of 7-(R)- and 7-(S)-methyl-2-nitro-6-(S)-(4-(trifluoromethoxy)benzyloxy)6,7-dihydro-5H-imidazo[2,1-b][1,3]oxazines, analogues of PA-824

被引：65

作者：

Li, Xiaojin ^{[1
]}

Manjunatha, Ujjini H. ^{[1
]}

Goodwin, Michael B. ^{[1
]}

Knox, John E. ^{[2
]}

Lipinski, Christopher A. ^{[3
]}

Keller, Thomas H. ^{[2
]}

Barry, Clifton E., III ^{[1
]}

Dowd, Cynthia S. ^{[1
]}

机构：

[1] NIAID, TB Res Sect, NIH, Bethesda, MD 20892 USA

[2] Novartis Inst Trop Dis, Singapore 138670, Singapore

[3] Melior Discovery, Waterford, CT 06385 USA

来源：

BIOORGANIC & MEDICINAL CHEMISTRY LETTERS | 2008年 / 18卷 / 07期

关键词：

Mycobacterium tuberculosis; PA-824; solubility; water solubility;

D O I：

10.1016/j.bmcl.2008.03.011

中图分类号：

R914 [药物化学];

学科分类号：

100701 ;

摘要：

Nitroimidazoles such as PA-824 and OPC-67683 are currently in clinical development as members of a promising new class of therapeutics for tuberculosis. While the antitubercular activity of these compounds is high, they both suffer from poor water solubility thus complicating development. We determined the single crystal X-ray structure of PA-824 and found a close packing of the nitroimidazoles facilitated by a pseudoaxial conformation of the p-trifluoromethoxybenzyl ether. To attempt to disrupt this tight packing by destabilizing the axial preference of this side chain, we prepared the two diastereomers of the 7-methyl-nitroimidazo-oxazine. Determination of the crystal structure of the 7-(R)-methyl derivative (5, cis) revealed that the benzylic side chain remained pseudoaxial while the 7-(R)-methyl derivative (6, trans) adopted the desired pseudoequatorial conformation. Both derivatives displayed similar activities against Mycobacterium tuberculosis, but neither showed improved aqueous solubility, suggesting that inherent lattice stability is not likely to be a major factor in limiting solubility. Conformational analysis revealed that all three compounds have similar energetically accessible conformations in solution. Additionally, these results suggest that the nitroreductase that initially recognizes PA-824 is somewhat insensitive to substitutions at the 7-position. (C) 2008 Elsevier Ltd. All rights reserved.

引用

页码：2256 / 2262

页数：7