Crystal Structure of 2-（2-Carboxy-4-hydroxy-6- methoxyphenoxy）-3,5-dichloro-6-hydroxy- 4-methylbenzoic Acid 1-Methyl Ester

The title compound, neogeodin hydrate （C17H14C1208, CAS： 94540-50-8）, was derived from marine fungus Aspergilhts terreus CRIM301. It was unequivocally characterized by IR, NMR spectroscopies, and single-crystal X-ray crystallography and tested for various biological activities. Neogeodin hydrate crystallizes in the triclinic space group P1 with a = 8.1159（5） A, b = 8.2472（4） A, c= 14.1278（7） A, a = 81.448（2）°, β = 84.860（2）°, γ= 70.400（2）°, V = 880.13（8） A3; Z = 2. It comprises a diphenyl ether, asterric acid skeleton and dichloro substituents. The methoxyphenoxy rings of the inversely related molecules form a ribbon-like structure that is stabilized by O-H...O hydrogen bonds through the doubly disordered carboxyl groups and by C-H...O interactions, generating the same R22（8） ring motif. The chlorinated methylbenzoate rings, making mostly a right angle, link the parallel upper and lower ribbons via bifurcated O-H...O and C-H...O hydrogen bonds, yielding endless channels. The channels formed are further sustained by C-H...O and π...π interactions Neogeodin hydrate exhibits inhibition against superoxide anion radical formation in the xanthine/xanthine oxidase （XXO） assay, but has no aromatase inhibitory activity.     

Stereoselective Synthesis of [2S,3R]-β-Hydroxy Ornithine

(2S,3R)-threo-β-hydroxy ornithine has been synthesized in a stereoselective manner by the C₂ opening of epoxyalcohol 9 with benzyl isocyanate.

     

PPh3-KOBut–Mediated Cyclization Reaction of β-Ketoesters with Alkynyl Ketones: Synthesis of Functionalized 2-Pyrones

Cyclization of alkynyl ketones with β-ketoesters mediated by PPh₃ and KOBu^t to synthesize 2-pyrone derivatives was systematically described. A variety of β-ketoesters reacted with alkynyl ketones to give functionalized 2-pyrones in moderate to good yields under mild conditions.      

Asymmetric Yttrium-Catalyzed C(sp3)−H Addition of 2-Methyl Azaarenes to Cyclopropenes

An enantioselective C−H addition to a C=C bond represents the most atom-efficient route for the construction of chiral carbon–carbon skeletons, a central research topic in organic synthesis. We herein report the enantioselective yttrium-catalyzed C(sp³)−H bond addition of 2-methyl azaarenes, such as 2-methyl pyridines, to various substituted cyclopropenes and norbornenes. This process efficiently afforded a new family of chiral pyridylmethyl-functionalized cyclopropane and norbornane derivatives in high yields and high enantioselectivities (up to 97 % ee).     

The Synthesis and Characterization of [4-CH3OC6H4CH2NH3]4P2O7·6H2O

Inorganic–organic hybrid compounds exhibit interesting properties in several application areas. In this regard, chemical preparation and characterization by X-ray diffraction, thermal analysis, and IR spectroscopy are given for a new organic cation diphosphate [4-CH₃OC₆H₄CH₂NH₃]₄P₂O₇·6H₂O. This later crystallizes in a C2/c unit cell with a = 38.238(6)Å, b = 6.453(1)Å, c = 16.942(7)Å; β = 97.60(4)°; Z = 4; and V = 4144(2)ų and D_x = 1.377 g·cm^?3. Its crystal structure has been determinated and refined to R = 0.044, using 7978 independent reflections. This atomic arrangement consists of inorganic layers built up from P₂O₇ ^4? anions and water molecules. On these layers, which are parallel to the (b, c) planes, the (4-CH₃OC₆H₄CH₂NH₃)⁺ cations are anchored through multiple hydrogen bonds.     

Synthesis of 3 or 4-Substituted Pyridine-2, 6-Dicarboxylic Acid

Time-resolvedcircularlypolarizedluminescence(CPL)studieshavebeenparticularlysuccessfulatmeasuringdifferencesinquenchingrateconstantsincertaindiastereomericdonor-acceptorsystems'ItisanticipatedthatthesetypesofexperimentsmaybeappliedtomorecomplexsystemsinvolvingracemiclanthanideemittercomplexesinasolutioncontainingtransitionmetalcomplexesenantioselectivelyboundtoDNA2.However,theluminophoreswereonlyconfinedtoLn(DPA),'-andLn(CDA),'(Ln=Eu' ,Tb' ,DPA=dipicolinatedianion,CDA=chelidamate).Eff…     

Synthesis of 3-Phenyl-6-formyl-3, 4-dihydro-2H-1, 3-benzoxazine

Benzoxazine is a novel class of thermosetting resins, which possesses lots of outstanding properties such as no by-products and near-zero shrinkage during polymerization as well as good molecular design flexibility1-2. Furthermore, polybenzoxazines (PBZs)…     

Enantioselective Synthesis of cis-Decalin Derivatives by the Inverse-Electron-Demand Diels–Alder Reaction of 2-Pyrones

A novel strategy for the synthesis of cis-decalins by an ytterbium-catalyzed asymmetric inverse-electron-demand Diels–Alder reaction of 2-pyrones and silyl cyclohexadienol ethers is reported here. A broad range of synthetically important cis-decalin derivatives with multiple contiguous stereogenic centers and functionalities are obtained in good yields and stereoselectivities. A full set of diastereomeric substituted cis-decalin motifs are readily accessible by tuning the absolute configurations of substituted silyl cyclohexadienol ethers (R or S) as well as the ligands (R or S). The synthetic potential is showcased by the enantioselective total synthesis of 4-amorphen-11-ol, and further demonstrated by the first total synthesis of cis-crotonin.     

Photo-isomerization of Aromatic α-Hydroxy Hydrazone

Photo-isomerization of aromatic α-hydroxy hydrazone was reported. We investigated the structures of salicylaldehyde phenylhydrozone(SP) in the ground state using density functional theory(DFT) with the B3LYP functional and the 6-311+G(d) basis set. All nine possible isomers of SP in the ground state consist of seven phenol forms and two ketone forms. Intrisic reaction coordinate(IRC) analysis discloses the existence of a cycle driven by the two proton transfer processes in the ground and excited states of SP, which suggests that no ketonic form could exist in the ground state. Further theoretical studies of the potential energy surfaces support a trans-cis conversion followed by a relaxation to the stable form of SP in the excited states.     

Structural and Physicochemical Studies of [4-ClC6H4CH2NH3]4Li2P6O18·4H2O

The crystal structure of a new organic cation cyclohexaphosphate, [4-ClC ₆ H ₄ CH ₂ NH ₃ ] ₄ Li ₂ P ₆ O ₁₈ .4H ₂ O, is reported. It crystallizes in the triclinic system (space group P-1) with the following unit-cell parameters: a = 9.628(8), b = 12.801(9), c = 19.528(6) Å, α = 78.60(4)°, β = 83.00(5)°, β = 89.98(4)°, Z = 2, and V = 2341(3)Å ³ . The structure has been solved using direct methods and refined by least-squares analysis [R ₁ = 0.043, wR ₂ = 0.108]. The structure can be described as infinite anionic layers with composition of [Li ₂ (P ₆ O ₁₈ )(H ₂ O) ₄ ] ^{4 ?} and parallel to the ac plane. The organic groups are located in the accessible voids. The molecules are stabilized by O─H…O and N─H…O types of intermolecular hydrogen bonds in the unit cell in addition to Van der Waals forces.     

Crystal Structure of 3-(4-nitro-) phenylsulfonyloxyisothiazole NO_2C_6H_4SO_3C_3H_2NS

1INTRoDUCTIONFollowingpublicationofthefirstsynthesisofamononuclearisothiazoleinl956(li,thisringsystemhasattractedconsiderableinterest.Especially,thistenden-....1cyisincreasingsincealotOfreportsaboutexcellentbiologicalactivitiesofcompoundscontainingisothiazolemoietyemergerecently"~".Theincreasingunderstandingofthefundamentalchemistryoftheisothiazolesystemhasenabledchemiststoincorpo-ratetheringintoawidevarietyofcompoundswithpotentialbiologicalactivity.Inanattempttolookforbiologicallyactivec…     

On The Protection of 3α-Hydroxy Group of A/B cis Steroids

The difficulties encountered in the protection of 3α-hydroxy group of lithocholic acid 1 with three different types of protective groups are described. Only benzyl ether derivative was found to be suitable for synthetic transformations. The methodology for the synthesis of benzyl ethers of A/B cis steroids is reported for the first time.     

Enantioselective Construction of 3-Hydroxy Oxindoles via Decarboxylative Addition of β-Ketoacids to Isatins

The first highly enantioselective decarboxylative addition of β-ketoacids to isatins mediated by a bifunctional tertiary amine-thiourea catalyst has been developed, allowing facile synthesis of biologically important 3-hydroxy oxindoles in good yields and excellent enantioselectivities. The method reported represents a valuable approach of utilizing β-ketoacids as synthetic equivalents of aryl/alkyl methyl ketone enolates.     

FTIR spectra of the 2ν4, ν4 + ν6 and 2ν6 bands of formaldehyde

High resolution IR spectra of the overtones and the combination band of the ν₄ and ν₆ modes of formaldehyde (2ν₄, ν₄ + ν₆ and 2ν₆) were measured in the region of 2200–2650 cm⁻¹ using FTIR. The combination band ν₄ + ν₆, whose dipole transition is forbidden from molecular symmetry, was observed due to the intensity borrowed from the other bands. The observed frequencies were analysed by a Hamiltonian in which A-type Coriolis interactions and Darling—Dennison interaction were taken into account. The ratio and the relative signs of the transition dipole moments of the overtone bands, μ_2ν4 and μ_2ν6, have been determined by analysing the intensity distribution of the vibration—rotation lines.     

Microwave Synthesis of 3,3＇-Bisazidomethyl Oxetane-3-Azidomethyl-3＇-Methyl Oxetane Random Copolymer

以1,4-丁二醇/三氟化硼·乙醚为引发体系,通过阳离子开环共聚合方法合成了3,3＇-双溴甲基环氧丁烷-3-溴甲基-3＇-甲基环氧丁烷（BBMO-BrMMO）无规共聚物,采用13CNMR进行了结构表征.然后用微波法对BBMO-BrMMO无规共聚物进行大分子叠氮化反应,合成了3,3＇-双叠氮甲基环氧丁烷-3-叠氮甲基-3＇-甲基环氧丁烷（BAMO-AMMO）无规共聚物,并对叠氮化反应动力学进行了研究.结果表明,BBMO-BrMMO无规共聚物的共聚组成和微观序列分布可以通过调节单体的物质的量配比实现可控性.叠氮化反应速率由相转移催化剂四丁基溴化铵（TBAB）的用量控制,反应速率常数为k=48.85L/（mol·h）（TBAB=1%）;k=51.95L/（mol·h）（TBAB=5%）;k=62.72L/（mol·h）（TBAB=10%）.微波法缩短了叠氮化反应时间,提高了合成过程的安全性,并且未改变共聚物的链结构.     

Synthesis of 2-Alkyl（aryl）-3-methylthio-6-methyl-6-arylpyrano-[4, 3-c]pyrazol-4（2H）-ones

The synthesis of 2-alkyl(aryl)-3-methylthiopyrano[4,3-c]pyrazol-4(2H)-ones via 5, 6-dihydro-2H-pyran-2, 4-dione-3-dithioacetals with (un)substituted hydrazines is described and the mechanism of the formation of title compounds is discussed. Their structures were confirmed by ^1HNMR spectra and elemental analysis.     

An Improved Synthesis of 2′-Hydroxy-3′,4′,6′-trimethoxyacylophenones

A wide variety of 2′-hydroxypolymethoxyacetophenones and propiophenones, e.g. 1a and 1b are used in the synthesis of flavone and ehromone natural products.¹ Repeated attempts to prepare 1a and 1b by reacting 1,2,3,5-tetramethoxybenzene 2 with acetyl or propionyl chlorides and AlCl₃ in ether² gave products which were difficult to purify.³ We traced the problem to ring-ethoxy contaminants which were isolated and tentatively identified as 3a and 3b.     

Hydrothermal Synthesis and Crystal Structure of a New Phosphonate： {[Cu（1,10-phen）]2-（H2O3PCH2C6H4C6H4CH2PO3H）2-（HO3PCH2C6H4C6H4CH2PO3H） }n

1 INTRODUCTION Metal organophosphonates have attracted considerable attention for over three decades due to their potential or practical applications, include- ing ion exchanges[1, 2], molecular sensors[3] and optics[4, 5]. Recently, a number of porous m…