Synthesis of 5-substituted-3-[(2′S,3′S)-3′-hydroxy-2′-hydroxymethyltetrahydrofuran-3′-yl]-1,2,4-oxadiazoles and their epimers

5-Phenyl-3-[(2′R,3′S)-3′-hydroxy-2′-dimethoxymethyltetrahydrofuran-3′-yl]-1,2,4-oxadiazole 10a and its epimer 11a, 5-methyl-3-[(2′R,3′S)-3′-hydroxy-2′-dimethoxymethyltetrahydrofuran-3′-yl]-1,2,4-oxadiazole 10b and its epimer 11b were synthesized from cyanohydrin benzoates 8a, 9a and cyanohydrin acetates 8b, 9b, respectively, by treatment with hydroxylamine in methanol via intramolecular transacylation and subsequent cyclization of the corresponding amidoximes. Hydrolysis and reduction of the dimethoxymethyl groups in the above compounds gave the desired compounds 12a, 13a, 12b and 13b.     

Asymmetric Synthesis of (S)-Dimethyl-4,4′-dimethoxy-5,6,5′,6′-dimethenedioxybiphenyl-2,2′-dicarboxylate

Schizandra chinesis(wuweizi)has long been used in Chinese herbal medicine.Schisandrin C,as a constituent of Schizandra chinesis,shows various pharmacologicalactivities1.The similar compound,dimethyl-4,4′-dimethoxy-5,6,5′,6′-dimethenedi-oxy-biphenyl-2,2′-dicarboxylate(α-DDB),discovered by Xie2,3et al.in the investing-ation of schisandrin C,and some derivatives have also exhibited anti-HIV and anti-HBVactivity4.Further study of this kind of biphenyls has attracted considerable attenti…     

Synthesis of betulonic acid S,S′-bis(carboxymethyl) dithioketal

Russian Chemical Bulletin - Betulonic acid S,S′-bis(carboxymethyl) dithioketal was obtained by condensation of betulonic and thioglycolic acids.     

Organocopper-mediated two-component S N2′-substitution cascade towards N-fused heterocycles

Organocuprates efficiently undergo reaction with heterocyclic propargyl mesylates at low temperature to produce N-fused heterocycles. The copper reagent plays a “double duty” in this cascade transformation, which proceeds through an S _N2′-substitution followed by a consequent cycloisomerization step.     

棒丝氨酸的全合成研究 Ⅰ.从D-葡萄糖合成3-[(3′R,5′S)-7′-氧代-1′-氮杂-4′-氧杂双环[3.2.0]-庚-3′-基]-3-O-苄基-(2S,3S)-丝氨酸及其(3′R,5′R)-差向异构体

以D-葡萄糖为原料经侧链氨基酸合成,与β-内酰胺缩合,嗯唑烷环合和除保护基等反应合成了棒丝氨酸的O-苄基衍生物,3-[(3′R,5′S)-7′-氧代-1-氮杂-4-氧杂双环[3.2.0]-庚-3′-基]-3-O-苄基-(2S,3S)-丝氨酸(17)及其(3′R,5′R)差向异构体(18)。     

Stereoselective total synthesis of (+)-(6R,2′S)-cryptocaryalactone and (−)-(6S,2′S)-epi cryptocaryalactone via asymmetric acetate aldol reaction

The total synthesis of (+)-(6R,2′S)-cryptocaryalactone and (?)-(6S,2′S)-epi cryptocaryalactone is reported based on asymmetric acetate aldol reaction. Still–Gennari reaction, Evans acetal intramolecular oxa-Michael reaction and lactonisation are the key steps in the target synthesis.     

An efficient and stereoselective synthesis of (2S,1′S,2′S)-2-(carboxycyclopropyl) glycine (LCCG-I): conformationally constrained l-glutamate analogues

Conformationally restricted metabotropic glutamate receptor agonist (2S,1′S,2′S)-2-(Carboxycyclopropyl) glycine (LCCG-I) 1 have been efficiently synthesized in a stereoselective manner. A convenient five step synthesis of 1 from readily available (−)-dimenthyl (1S,2S)-cyclopropane-1,2-dicarboxylate 5 in 49% overall yield is described.     

Synthesis and Structure Determination of (2S, 2′S)-3-Phenyl-2-(pyrrolidin-2′-yl)- propionic Acid

Abstract

Aβ²,β³-homoproline derivative, (2S, 2′S)-3-phenyl-2-(pyrrolidin-2′-yl)propionic acid, was synthesized starting from l-proline. After preparation of the (4S, 4aS)-4-benzyl-4a,5,6,7-tetrahydro-pyrrolo-[1,2-c]pyrimidine-1,3-dione under a mild condition, the absolute configuration of target compound was assigned using 2D H-H COSY and H-H NOESY technologies.     

Enantioselective synthesis of (2S,2′R)-erythro-methylphenidate

A new approach towards the enantioselective synthesis of (2S,2′R)-erythro-methylphenidate (1) is described. The key step in the synthesis utilizes Evans' 4-substituted-2-oxazolidinone chiral auxiliary to control the diastereofacial selectivity in the hydrogenation of enamine intermediate 6, yielding the hydrogenated product 7 with excellent diastereoselectivity. Methanolysis of 7 afforded 1 with excellent enantiopurity.     

hKv4.3基因5′非翻译区序列S160功能分析

hKv4.3基因是形成瞬时外向钾电流Ito的主要分子基础,它在心脏和神经细胞中大量表达,但在其它组织中则未见大量表达.为了研究hKv4.3表达在基因水平的调节,将hKv4.3基因的5′非翻译区的一段序列( 2~ 160,称之为S160)克隆到报告质粒中,进行瞬时表达.发现S160对hKv4.3基因的启动子和SV40的启动子都有强烈的抑制作用,没有方向特异性,但却有位置特异性.经删除突变分析,在S160片段中发现了一个抑制元件S(GAGGGGTTAA),它位于hKv4.3基因中转录起始位点下游20~30bp处.在此基础上,用RT-PCR方法对mRNA进行定量分析,初步确认这个抑制元件对蛋白表达的抑制过程是在翻译水平上.     

2-{(4a′S,6a′S,10a′R,10b′R)-Octahydrospiro[1,3-dioxolane-2,2′-pyrano[2,3-c]chromen]-6a′(1′H)-yloxy}ethanol in the Synthesis of (2S)- and (2R)-Dodecane-1,2-diols

Russian Journal of Organic Chemistry - Michael adduct of levoglucosenone and cyclohexanone, 1,6-anhydro-3,4-dideoxy-4-C-(2-oxocyclohexan-1-yl)-β-D-erythrohexo-2-ulose, was treated with...     

Synthesis and applications of (R)- and (S)-7,7′-dimethoxy-2,2′-bis(diphenylphosphino)-1,1′-binaphthalene

The synthesis of (R)- and (S)-7,7′-dimethoxy-2,2′-bis(diphenylphosphino)-1,1′-binaphthalene 5a and 5b is described. The phosphorus atoms in (S)-(−)-5b are shown to be slightly more basic than the phosphorus atoms in (S)-BINAP by comparing the magnitude of the ¹J (³¹P–⁷⁷Se) coupling constant in their respective diselenide derivatives. (S)-(−)-5b behaved similarly to (S)-BINAP in asymmetric Heck reactions.     

Synthesis of 2′(S), 3′(R),5′-trihydroxypentyladenine

A synthesis of 2′(S), 3′(R),5-trihydroxypentyladenine (1) from D-ribonic acid γ-lactone (2) is described.     

Poly[cadmium(II)-μ-4,4′-oxydianiline-N:N′-di-μ-thiocyanato-N:S]

The title polymeric complex, [Cd(SCN)₂(C₁₂H₁₂N₂O)], exhibits a three-dimensional framework in which each Cd^II atom is bridged by two η-1,3-(SCN)⁻ groups, forming a double-stranded chain. The unique Cd^II atom lies on an inversion centre and the coordination sphere is completed by two terminal N atoms from two different 4,4′-oxy­dianiline (4,4′-Oda) ligands, furnishing a CdS₂N₄ octahedral geometry. Adjacent polymeric double-stranded chains are linked via the 4,4′-Oda ligands, which lie across twofold rotation axes.     

Synthesis of (1′S*,2R*,3R*)- and (1′S*,2R*,3S*)-N-arylsulfonyl-2-(1′-halogenethyl)-3-methylindolines and their selective toxicity against SH-SY5Y cell line

N-tosyl-2- and N-tosyl-4-halogen-substituted derivatives of 2-(1-methylbut-2-en-1-yl)aniline were synthesized and their molecular iodine-mediated cyclization was investigated. The cyclization upon interaction of N-tosyl-6-methyl-2-(1-methylbut-2-en-1-yl)aniline with molecular iodine in methyl tert-butyl ether or acetonitrile was studied, as well as the interaction of this sulfonamide with N-bromosucinimide in dichloromethane. Synthesized (2R*,3R*)- and (2R*,3S*)-N-arylsulfonyl-2-(1-halogenoethyl)-3-methylindoline derivatives showed cytotoxic activity against HEK293 cells, SH-SY5Y, Jurkat, and HepG2 cell lines. The compounds (2R*,3S*)-N-arylsulfonyl-7-bromo-2-(1-halogenoethyl)-3-methylindoline cis- 4a , stereoisomeric (2R*,3R*)-trans- 4h and (2R*,3S*)-N-tosyl-7-chloro-2-(1-halogenoethyl)-3-methylindoline cis- 4h demonstrated selective toxicity against SH-SY5Y cell line (IC₅₀ ≈ 3 ÷ 5 μM), and did not affect HEK293, Jurkat, and HepG2 cells.     

Optical Rotatory Feature of (R or S)-1,1′-Binaphthalene-2,2′-diol (BINOL) in Various Solvents

IntroductionElieletal.1,2 haveeverreportedthatsolventtypeandconcentrationwouldaffecttheequilibriumofcis 3 hydrox ythiane S oxideconformationwhichwascausedbyintermolec ularandintramolecularhydrogenbondformedwiththeinter actionbetweenthesolute solventandthesolute soluteinthesolutionandhaveimportantinfluenceonitsspecificrotation .Uptonowitisnotveryclear,however,whetherhydrogenbondingaffectsspecificrotation (inmagnitudeandoccasion allyinsign)directlyorwhetheritdoessoindirectly (byaf fectingconform…