A Streamlined Regenerative Glycosylation Reaction: Direct, Acid‐Free Activation of Thioglycosides
作者:Samira Escopy、Yashapal Singh、Keith J. Stine、Alexei V. Demchenko
DOI:10.1002/chem.202003479
日期:2021.1.4
(HOFox) is able to mediate glycosylations via intermediacy of OFox imidates. Thioglycoside precursors were first converted into the corresponding glycosyl bromides that were then converted into the OFox imidates in the presence of Ag2O followed by the activation with catalytic Lewis acid in a regenerative fashion. Reported herein is a direct conversion of thioglycosides via the regenerative approach
S-Thiazolinyl (STaz) Glycosides as Versatile Building Blocks for Convergent Selective, Chemoselective, and Orthogonal Oligosaccharide Synthesis
作者:Papapida Pornsuriyasak、Alexei V. Demchenko
DOI:10.1002/chem.200600262
日期:2006.8.25
In the aim of developing new procedures for efficient oligosaccharide assembly, a range of S-thiazolinyl (STaz) glycosides have been synthesized. These novel derivatives were evaluated against a variety of reaction conditions and were shown to be capable of being chemoselectively activated in the armed-disarmed fashion. Moreover, the S-thiazolinyl moiety exhibited a remarkable propensity for selective
Heterocyclic analogues of l -citrulline as inhibitors of the isoforms of nitric oxide synthase (NOS) and identification of N δ -(4,5-dihydrothiazol-2-yl)ornithine as a potent inhibitor
作者:Saraj Ulhaq、Edwin C Chinje、Matthew A Naylor、Mohammed Jaffar、Ian J Stratford、Michael D Threadgill
DOI:10.1016/s0968-0896(99)00136-4
日期:1999.9
synthesised. In two of these, the S-substituent was 'tied back' sterically by cyclisation to the nitrogen remote from the amino-acid unit. N(delta)-(4,5-Dihydrothiazol-2-yl)ornithine was identified as an inhibitor of rat inducible and constitutive isoforms of NOS and of a constitutive NOS derivedfrom a human tumour xenograft. Analogous N(delta)-(thiazol-2-yl)ornithines were less active, whereas the corresponding
L-硫代瓜氨酸是已知的几种一氧化氮合酶 (NOS) 同种型的强效抑制剂。为了比以前报道的更深入地探索该分子的构效关系 (SAR),合成了三种取代异硫脲硫的类似物。在其中两个中,通过环化到远离氨基酸单元的氮,S-取代基被空间“束缚”。N(delta)-(4,5-Dihydrothiazol-2-yl)ornithine 被确定为大鼠诱导型和组成型 NOS 和源自人类肿瘤异种移植物的组成型 NOS 的抑制剂。类似的 N(delta)-(thiazol-2-yl)ornithines 活性较低,而相应的 N(delta)-(oxazol-2-yl)ornithine 和 N(delta)-(pyrimidin-2-yl)ornithine 完全失效抑制 NOS。已开发出一种新的有效制备关键合成中间体 N(α)-Boc-硫代瓜氨酸叔丁酯的方法。用 2-氨基-5-(杂环硫基)戊酸(由 2-(Boc-
Hydrogen-Bond-Mediated Aglycone Delivery (HAD): A Highly Stereoselective Synthesis of 1,2-<i>cis</i>α-<scp>D</scp>-Glucosides from Common Glycosyl Donors in the Presence of Bromine
作者:Jagodige P. Yasomanee、Alexei V. Demchenko
DOI:10.1002/chem.201406589
日期:2015.4.20
H‐bond mediated aglyconedelivery (HAD) method recently introduced by our laboratory. At first it was noticed that high α‐stereoselectivity is only obtained with S‐ethyl glycosyldonors and only in the presence of dimethyl(methylthio)sulfonium trifluoromethanesulfonate (DMTST), in high dilution, and low temperature. Combining the mechanistic studies of the HAD reaction and bromine‐promoted glycosylations
Radical–nucleophilic substitution (S<sub>RN</sub>1) reactions. Part 2. Preparation and reactions of α-nitrosulphides
作者:W. Russell Bowman、Devajvoti Rakshit、Michael D. Valmas
DOI:10.1039/p19840002327
日期:——
to the anion of 2-nitropropane, SN2 attack of the anion of 2-nitropropane on symmetrical disulphides, and SRN1reaction of 2-substituted-2-nitropropanes with thiolate anions. The α-nitrosulphides undergo SRN1 substitution with the anion of 2-nitropropane, and SRN1 substitution or redox reactions with thiolate anions. The electron spin resonance (e.s.r.) spectrum of the radical-anion of 1-methyl-1-nitroethyl