Synthesis of 1-[6-Fluoro-(2S)-3H,4H-dihydro-2H-2-chromenyl]-(1R)-1,2- ethanediol and 1-[6-Fluoro-(2R)-3H,4H-dihydro-2H-2-chromenyl]- (1R)-1,2-ethanediol

Benzopyran compounds possess diverse pharmacological properties such as β-blockade, anticonvulsant and antimicrobial.[1,2] Our interest has been focused on the synthesis of 1-[6-Fluoro-2S]-3H,4H-dihydro-2H-2-chromenyl]-(1R)-1,2-ethanediol (6) and 1-[6-fluoro-(2R)-3H,4H-dihydro-2H-2-chromenyl]-(1R)-1,2-ethanediol (7) which are particularly convenient precursor to (S,R,R,R)-NE (8). 8 containing four asymmetrical carbon atoms was reported to be the most active isomer.[3] Chandrasekhar[4] has reported on the synthesis of 8. The key step to synthesize this compound is to obtain the chiral chromanone 6 and 7. 6 was accomplished in 8 steps by the Clasien rearrangement and a one-pot Sharpless asymmetric epoxidation, but the compound 7 was accomplished in 10 steps. Johannes[5] used Zr-catalytic kinetic resolution of allylic ethers and Mo-catalyzed chromene formation to synthesize 8 in 14 steps. However both of the methods request many synthetic steps and expensive reagents.     

Asymmetric Conjugate Addition of Alcohols to (R)-(-)-5-[(1R,2S,5R)-Menthyloxy]-2-(5H)-Furanone

(R)-(-y5-[(IR,2S,5R)-menthyloxy](1)isausefulchiralsynthonreadilypreparedonatWo-stepprocedure-l']FindingsoffuranoneringsexistingascomponentSofsomenaturalproductSI'laswellastheiractivereactivityl']havestimu1atedeXtensiveresearchofitSasymmetricreactionswhichincludeDiels-Alderreactions,l']l,3-dipo1arcycloadditions,['1Michaelauditionsl5]andconjugateedditionsofaminesl']andmercaPtans.g4:,::7f:7':theseadductsledtovariousmultifunctionalhomochiralbuildingblockssuchas2-alkyl-l,4-butanediols,I'l2-aI…     

Cu-OMS-2-catalyzed decarboxylation–acetoxylation of (3R,4R)-4-acid-3-[(R)-1-((t-butyl-dimethylsilyl)oxy)-ethyl]-1-methoxyphenyl-2-azetidinone with NaBrO3/NaOAc

(3R,4R)-4-Acetoxy-3-[(R)-1((t-butyldimethylsilyl)oxy)-ethyl]-1-methoxyphenyl-2-azetidinone (an important precursor for the synthesis of carbapenem antibiotics) was synthesized under mild and green conditions catalyzed by Cu-OMS-2. Normal to excellent isolated yields were obtained under given conditions.     

Synthesis of pure methyl [(2S,3R,αR)-1-(3-bromo-4-methoxyphenyl)-3-(α-acetoxy)ethyl-4-oxoazetidin-2-carboxylate] and its enantiomer

Synthesis of key intermediates leading to 2-iso-oxacephems was carried out starting from l- and d-threonine. As predicted in our previous paper (Tetrahedron Lett. 1995, 36, 8303–8306) all diastereomers of 2-iso-oxacephems can be prepared from the appropriate enantiomers of the amino acid threonine. The absolute configuration of the 2,3- and α-carbon atoms in the β-lactam structure was determined by X-ray crystallographic studies.     

3-((1R,3aS,3aS,10aR)-十氢-(1H,4H)-吡啶并[1,6]萘啶-1-基)丙-1-胺的合成

以廉价易得的苦参碱为起始原料,经过开环、酯化反应、水解等步骤,得到4-((3aS,3aS,10aR)-2-(叔丁氧基羰基)十氢-(1H,4H)-吡啶并[1,6]萘啶-1-基)丁酸(5)。5再经过Curtius重排反应,得到叔丁基(1R,3aS,3aS,10aR)-1-(3-(((苄氧基)羰基)氨基)丙基)八氢-(1H,4H)-吡啶并[1,6]萘啶-2(3H)-羧酸叔丁酯(6)。然后,6脱去Cbz基团得到(1R,3aS,3aS,10aR)-1-(3-氨基丙基)八氢-(1H,4H)-吡啶并[1,6]二氮杂萘-2(3H)-羧酸叔丁酯(7),最后,7脱去Boc基团成功得到苦参碱衍生物的重要中间体3-((1R,3aS,3aS,10aR)-十氢-(1H,4H)-吡啶并[1,6]萘啶-1-基)丙-1-胺(8),总收率28%。目标化合物和中间体的结构经¹H NMR, ¹³C NMR和HR-MS确证。      

Synthesis of 5-Substituted-3-[ (2＇R,4＇R)-4＇-Hydroxy-2＇-hydroxymethyl tetrahydrofuran-4＇-yl ]-1,2,4-oxadiazoles and Their Epimers

The syntheses of 5-substituted-3-[(2＇ R＇ 4＇ R)-4v -hydroxy-2＇-hydroxymethyltetrahydrofuran-4＇-yl]-1, 2,4-oxadiazoles and their epimers were accomplished with the aid of the construction of 1, 2, 4-oxadiazoles by condensation of O-acylated cyanohydrins with hydroxylamine via intramolecular transacylation and subsequent cyclization.     

Stereoselective synthesis and absolute configuration of (1′R,3R,4R)-4-acetoxy-3-(2′,2′,2′-trifluoro-1′-hydroxyethyl)azetidin-2-one

The title compound 3, an intermediate in the synthesis of fluorocarbapenems, is obtained with high stereocontrol by the condensation of (R)-(+)-ethyl 4,4,4-trifluoro-3-hydroxybutanoate with N-trimethylsilyl cinnamylidenimine. X-Ray diffraction analysis of the condensation product and chemical correlations allowed the unambiguous determination of the absolute configuration.     

Synthesis of 4′-[3-methyl-5-thioxo-1H-1,2,4-triazol-4(5H)-yl]-2′,5′-diphenyl-2′,4′-dihydro spiro[indolin-3,3′[1,2,4]triazol]-2-one derivatives

In this paper 1,3-dipolar cycloaddition reaction has been studied. An efficient synthesis of 4′-[3-methyl-5-thioxo-1H-1,2,4-triazol-4(5H)-yl]-2′,5′-diphenyl-2′,4′-dihydro spiro(indolin-3,3′[1,2,4]triazol)-2-one derivatives using triethylamine in MeCN at room temperature is reported. The structures of the obtained compounds were confirmed by means of elemental analysis, MS and spectral (IR, ¹H, and ¹³C NMR) methods.     

Synthesis of 5-Substituted-3-[(2’R,4’R)-4’-Hydroxy-2’-hydroxymethyltetrahydrofuran-4’-yl]-1,2,4-oxadiazoles and Their Epimers

The syntheses of 5-substituted-3-[( 2' R, 4' R)-4 ' -hydroxy-2 ' -hydroxymethyltetra-hydrofuran-4' -yl]D-1 ,2, 4-oxadiazoles and their epimers were accomplished with the aid of th construction of 1,2, 4-oxadiazoles by condensation of O-acylated cyanohydrins with hydroxylamine via intramolecular transacylation and subsequent cyclization.     

One Pot Synthesis of Some New Spiro[3H-Indol-3,5′(4′H)-[1,2,4] Oxadiazol]-2-Ones and Bis[Spiro[3H-Indol-3,5′(4′H)-[1,2,4] Oxadiazol]-2-Ones]

A facile preparation of the title compound by 1,3-dipolar cycloaddition reaction of benzonitrile oxides with isatin imines or isatin diimines, in excellent yield, are reported.     

3-取代-(1H)-嘧啶[1, 2-a]喹啉-1-酮和2-取代嘧啶[1, 2a]苯骈 咪唑-4-(10H)- 酮的简便合成法

本文利用2-氨基喹啉和2-氨基苯骈咪唑作为亲核试剂,与5-(双甲硫基亚甲基)丙二酸亚异丙酯(1)、5-(甲硫基亚烃基)丙二酸亚异丙酯(3)反应,开发出3-取代-(1H)-嘧啶-[1,2-a]喹啉-1-酮(5)和2-取代嘧啶[1,2-a]苯骈咪唑-4-(10H)-酮(6)通用的简便合成法。     

Syntheses,Structure and Biological Activities of 2-(1H-Benzo [1,2,3]triazole-1-yl)-1-(3-methyl-4-bromobiphenyl)-2-(1H-1,2,4-triazole-1-yl)ethanone

Introduction1,2,4-Triazole derivatives represent an interesting class of heterocyclic compounds[1]and have become the most rapidly expanding group of antifungal compounds with the advantages of toxicity, high oral bioavailabi-lity, and broad spectrum of a…     

PREPARATION AND STRUCTURE OF TETRAMETHYLAMMONIUM HYDROGEN TRIPEROXOTRIMOLYBDODISULFATE TRIHYDRATE, [N(CH3)4]3[H(SO4)2-(MoO2(O2))3]· 3H2O

Abstract

A novel peroxopolyoxomolybdate compound, [N(CH₃)₄]₃ [H(SO₄)₂ (MoO₂(O₂))₃] · 3H₂O, has been obtained from a strongly acidic aqueous solution of a molybdate-sulfate system as the monoclinic crystal of P2/n, a = 13.497(3), b = 15.231(4), c = 32.603(2) Å, β = 103.113(9)°, and V = 6577(2) ų. The final R-value was 0.0986 for 395 parameters using 7162 reflections. Each of the two crystallographically independent polyanions contains three molybdenum atoms with five O^2?, one O₂ ^2?, and two sulfate groups, one of which is a tripod ligand apical to the molybdenum plane, and the other is a bipod ligand equatorial to the Mo plane.     

合成(3R,4R)-3-[(1'R)-叔丁基二甲基硅氧乙基]-4-乙酰氧基-2-氮杂环丁酮的新方法

(3R,4R)-3-[(1'R)-叔丁基二甲基硅氧乙基]-4'-乙酰氧基-1-对甲氧基苯基-2-氮杂环丁酮依次经铋酸钠/浓硫酸体系氧化和亚硫酸氢钠还原,合成了培南类药物的重要中间体——(3R,4R)-3-[(1'R)-叔丁基二甲基硅氧乙基]-4-乙酰氧基-2-氮杂环丁酮(1),收率62%,纯度98%,其结构经1H NMR,IR和EI-MS表征。     

Crystal Structure and Spectra Characters of 2-Benzoly-3-(4-(1,2,4-triazole)-5-anilino-thiophene and 2-(4-Methyl-benzoly)-3-(4- chlrolphenyl)-3-(1,2,4-triazole)-5-anilino-thiophene

Triazole derivatives are widely studied, because they represent the largest group of modern fungicides and are widely used both in human and veterinary therapy and in agriculture. We synthesized the title compound in which the thiophene ring was substituted by a 1,2,4-triazole group, a phenacyl group, a phenylaminol group and a benzene ring.     

Syntheses,spectroscopy, and X-ray structures of 3-{(R)-(Ar)-ethylimino}-1,3-dihydro-indol-2-one (Ar = Ph,MeOC6H4, BrC6H4, 1-naphthyl) and [Rh(η4-cod){3-((R)-(Ar)-ethylimino)-3H-indol-2-olato}]

Condensation of 1H-indole-2,3-dione (isatin) with (R)-(Ar)-ethylamines gives enantiopure Schiff bases, 3-{(R)-(Ar)-ethylimino}-1,3-dihydro-indol-2-one (HL) {Ar?=?Ph (HL1), 2-MeOC₆H₄ (HL2), 4-MeOC₆H₄ (HL3), 4-BrC₆H₄ (HL4), and 1-naphthyl (HL5)}. The Schiff bases readily coordinate to [Rh(μ-O₂CMe)(η⁴-cod)]₂ (cod?=?1,5-cyclooctadiene) to give mononuclear [Rh(η⁴-cod){3-((R)-(Ar)-ethylimino)-3H-indol-2-olato}] {Ar?=?Ph (1), 4-MeOC₆H₄ (2), and 4-BrC₆H₄ (3)}, respectively. The Schiff bases and complexes have been fully characterized by IR, UV-Vis, ¹H-NMR, mass, and circular dichroism (CD) spectrometry. Polarimetry and CD measurements show the enantiopurity of the Schiff bases as well as the complexes. ¹H NMR measurements reveal slow conversion of the lactam to the enol form of the Schiff bases in solution. In the solid state the lactam form dominates as shown by crystal structures of HL1 and HL4. While gross structural features of both are similar, the molecules differ significantly in the relative orientations of the aryl and lactam rings. The difference is mostly rotation about the N2–C9 bond with different C8–N2–C9–C11 torsion angle of +89.77(12)° for HL1 and C2–N2–C9–C11 of +106.8(3)° for HL4.     

Spin Crossover 1 A 1⇔ 5 T 2 in Solid Fe(trz)3x(atrz)3-3x(NO3)2·H2O (trz = 1,2,4-triazole, atrz = 4-amino-1,2,4-triazole)

The reaction of Fe(NO ₃ ) ₂ , trz, and atrz in ethanol–water gave solid Fe(trz) _3x (atrz) _3-3x (NO ₃ ) ₂ ·H ₂ O (x = 0.1, 0.2, 0.4, 0.8). The solids were investigated by magnetic chemistry, X-ray diffraction, photoelectron (DRS), IR, and Mössbauer spectroscopy methods. The individual Fe(trz)₃(NO₃)₂ and Fe(atrz)₃(NO₃)₂ as well as the solid phases exhibit a reversible spin crossover ¹ , whose temperature and character depend on the phase composition. Due to this, T _c may be changed by introducing another ligand into the complex exhibiting a spin crossover effect.     

Synthesis and Crystal Structure of 2,2-Dimethyl-4-[1H-（ 1,2,4-triazolyl）]-4- [ 1H-benzotriazolyl]-3- butanone[t-BuCOCH（C2H2N3）（C6H4N3）]

1 INTRODUCTION Triazole nuclei appear frequently in the structures of various natural products and biologically active compounds, notably thiamine (vitamin B), peni- cillins, antibiotics such as micrococcin[1], and many metabolic products of fungi and p…     

(1R,3S,4S)-2-苄氧羰基-2-氮杂双环[2.2.1]庚烷-3-羧酸的合成

以(R)-(+)-α-甲基苄胺为原料,依次经缩合,Diels-Alder反应,还原,Cbz-保护和水解反应,合成了抗丙肝新药HCV NS3/4A蛋白酶拟肽类抑制剂的重要中间体——(1R,3S,4S)-2-苄氧羰基-2-氮杂双环[2.2.1]庚烷-3-羧酸,总收率66%,其结构经1H NMR和ESI-MS确证。     

Tansition metal complexes with 2-(1-(carboxymethyl)-2-methyl-1H-benzimidazol-3-ium-3-yl)acetate (HL): Synthesis and crystal structure of [Co(L)2(H2O)4] · 6H2O and [Cu(L)2(H2O)2] · 4H2O

Transition metal complexes of 2-(1-(carboxymethyl)-2-methyl-1H-benzimidazol-3-ium-3-yl)acetate (HL), namely [Co(L)₂(H₂O)₄] · 6H₂O (I) and [Cu(L)₂(H₂O)₂] · 4H₂O (II), have been synthesized by a hydrothermal procedure and characterized by X-ray crystallography, CIF files CCDC nos. 1007524 (I), 1007525 (II). Both I and II are mononuclear molecules. In I, the Co²⁺ ion is in octahedral coordiantion environment and surrounded by four O atoms from water molecules and two carboxylate O atoms of two deprotonated ligand (L^?) occupied six culmination. While in II, the Cu²⁺ ion is located in a square-planar geometry, bounded to two aqua O atoms and two carboxylate O atoms from L^?.