CRYSTAL AND MOLECULAR STRUCTURE OF 3a-(4-CHLORO-PHENYL)-1, 5-DIPHENYL-3a, 4,5,11-TETRAHYDRO-1, 2, 4-OXA-DIAZOLINO [5,4-d][1, 5]BENZOTHIAZEPINE, (C_(28)H_(21)N_2OClS)

<正> The structure of 3a-(4-chlorophenyl)-1, 5-diphenyl-3a, 4,5,11-te-trahydrq-1, 2, 4-oxadiazolino [5, 4-d][1, 5] benzothiazepine (C28H21N2OClS) has been determined. The compound crystallizes in triclinic space group P1 with two formula units in a cell of dimensions: a =11. 114(2), b = 11. 673(1), c=10. 435(1) (?), α=98. 42(1), β=118. 69(1),γ = 98. 64(1)° and V = 1136. 2(3)(?)3. The structure was solved by using direct methods and refined by full matrix least-squares. The final crystallographic discrepancy factor is 0. 058 for 2384 observed reflections. The molecular backbone is a tricyclic system : The seven-membered hetero ring in the center is in twisted-boat conformation, and is cis-fused to 1, 2, 4-oxadiazolino ring which is in an envelope form, together with the equilaterally adjoined benzene ring . The compound has a non-planar conjugation system.     

Anhydrobiisatic acid 6:12-Oxa-5:6:11:12-tetrahydrophenhomazine-6:12-dicarboxylic acid

Anhydrobiisatic acid (IVa), a new type of compound containing the phenhomazine ring system, has been obtained by self-condensation of isatic acid—(o-aminophenyl)glyoxylic acid—. The structure of this acid has been established and derivatives have been prepared. N:N′-Dimethylanhydrobiisatic acid (IVc) has been resolved into optically active components.     

A novel tetracyclic ring system. 10H-tetrazolo[5′,1′:3,4][1,2,4]triazino[5,6-b]indole

The reaction of 3-hydrazino-1,2,4-triazino[5,6-b]indole with nitrous acid affords a novel tetracyclic ring system: 10H-tetrazolo[5′,1′:3,4][1,2,4]triazino[5,6-b]indole. The mode of cyclization has been discussed.     

Synthesis of L-β-(isoxazolin-5-one-2-yl)-alanine: a novel method for the synthesis of N-substituted 3,4-unsubstituted isoxazolin-5-ones

A mild new general method for the synthesis of the isoxazolin-5-one-2-yl ring system (4) via a favoured 5-endo-dig cyclisation is described; this methodology has been successfully applied for the first chemical enantio-efficient synthesis of $\text{L}$-β-(isoxazolin-5-one-2-yl)-alanine (3).     

Crystal Structure of 5-(l-Menthyloxy)-3-Chloro-4-Pyrrolidinyl-2(5H)-Furanone

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Spatial structure of 5-phenyl-5-oxo-2,4,6-triisopropyl-1,3,5-dioxa phosphorinane

Conclusions By means of x-ray structure analysis, it has been shown that the stereoisomer of 5-phenyl-5-oxo-2,4,6-triisopropyl-1,3,5-dioxaphosphorinane with mp 215°C has the chair conformation with all equatorial substituents of the ring atoms and axial substituents of the phosphoryl group. The conformations of the isopropyl groups are retarded relative to the ring bonds. The benzene ring at the P atom is perpendicular to the plane of the heterocycle.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No.3, pp. 599–603, March, 1982.     

Synthesis of D-hexos-5-uloses by novel in situ hydrolysis of epoxides derived from 6-deoxyhex-5-enopyranosides

[reaction: see text] Epoxides derived from 2,3, 4-tri-O-protected-6-deoxyhex-5-enopyranosides are hydrolyzed in situ to ultimately give novel protected-D-hexos-5-ulose derivatives (sugar 1,5-dicarbonyls, 5-ketohexoses) in moderate to high yields. The products adopt a bicyclic structure (1,6-anhydropyranos-5-ulose) in solution with the pyranose ring in (4)C(1) conformation. The methodology has been used to prepare D-xylo-hexos-5-ulose (5-ketoglucose), a synthetic precursor to 1-deoxynojirimycin and a possible intermediate in the biosynthesis of inositols.     

X-ray crystal structure of (eta(5)-pentaphenylcyclopentadienyl)[1-(eta(5/6)-phenyl)-2,3,4,5-tetraphenylcyclopentadienyl]iron(II), [Fe(eta(5)-C(5)Ph(5))[(eta(5/6)-C(6)H(5))C(5)Ph(4)]], a linkage isomer of decaphenylferrocene

Very dark blue prismatic crystals of [Fe(eta(5)-C(5)Ph(5))[(eta(5/6)-C(6)H(5))(C(5)Ph(4))]], the linkage isomer of decaphenylferrocene, were grown from (3:1 v/v) hexane/ethyl acetate and characterized by single-crystal X-ray diffraction (space group P2(1)/n, R1(F) 0.0404). The iron atom is coordinated to two C(5)Ph(5) ligands: one with an eta(5)-C(5)-configuration and the other with a coordinated arene configuration. The phenyl groups of the (eta(5)-C(5)Ph(5)) ligand are oriented in a "paddle-wheel" arrangement about the C(5) ring, with which four of them make an average angle of approximately 53 degrees, the other, an angle of approximately 42 degrees. The coordinated C(6)H(5) ring of the other ligand is inclined at only approximately 5 degrees to the uncoordinated C(5) ring, with which three of the other four phenyl rings make an average angle of approximately 64 degrees, and the other (opposite the coordinated arene ring), an angle of 38 degrees.     

Synthesis of the [5-7-6] tricyclic core of guanacastepene A via an intramolecular Mukaiyama aldol reaction

[reaction: see text] A synthesis of the tricyclic [5-7-6] skeleton of guanacastepene A is described. The six-membered ring of guanacastepene A was constructed by a Diels-Alder reaction. After several functional group transformations, it was coupled to beta-iodocyclopentenone. Lithium dimethylcuprate conjugate addition followed by an intramolecular Mukaiyama aldol reaction furnished the desired [5-7-6] tricyclic ring system.     

Synthesis of 1,2′,3,3′,5′,6′-hexahydro-3-phenylspiro[isobenzofuran-1,4′-thiopyrans] and 1,2′,3,3′,5′,6′-hexahydro-3-phenylspiro-[isobenzofuran-1,4′-pyrans]

The 1,2′,3,3′,5′,6′-hexahydro-3-phenylspiro[isobenzofuran-1,4′-thiopyran] ring system ( 2a ) has been prepared from o-bromobenzoic acid. The 1,2′,3,3′,5′,6′-hexahydro-3-phenylspiro[isobenzofuran-1,4′-pyran] ring system ( 3a ) has been prepared from 2-bromobenzhydrol methyl ether. Several 3-(dimethylaminoalkyl) derivatives of both 2a and 3a were prepared by lithiation followed by alkylation.     

Preparation of the 5/5-spiroketal of the ritterazines

The enantiomerically pure 5/5-spiroketal required for the synthesis of the ritterazines has been prepared with high diastereocontrol by ring closure followed by equilibration.     

Optical activity of lactones and lactams-III : Circular dichroism spectra of 5-oxazolidinones

The synthesis and the chiroptical properties of several 5-oxazolidinones derived from α-amino acids are reported. The existence of an equilibrium between the two enantiomeric envelope conformations of 5-membered ring has been inferred from CD and NMR spectra. In a few cases the small contribution of the planar ring conformation to the equilibrium is proposed. The nature of the lowest energy transition and the usefulness of the Weigang lactone sector rule for Cotton effect sign predictions are discussed on the basis of CNDO/2-CI calculations.     

Ring opening of 4',5'-epoxynucleosides: a novel stereoselective entry to 4'-C-branched nucleosides

Stereoselective synthesis of 4'-alpha-carbon-substituted nucleosides has been accomplished through epoxidation of 4',5'-unsaturated nucleosides with dimethyldioxirane (DMDO) and successive SnCl(4)-promoted ring opening of the resulting 4',5'-epoxynucleosides with organosilicon reagents. [reaction: see text]     

Synthesis and Crystal Structure of 5-Methoxy- butyrolacto[3,4-b]-1-N-cyclohexylaziridine

1 INTRODUCTION The study of aziridine derivatives has been an ac-tive area in organic chemistry due to their interestingreactive properties and special structures[1～3]. Aziri-dine compounds contain unique nitrogen skeleton ofthree-membered heterocycle, which is widely presentin many natural products. They have been used toobtain a variety of biologically important moleculessuch as amino acids, amino alcohols, alkaloids, andβ-lactam antibiotics[2～4]. Although the synthetic routesto azir…     

Intramolecular [2 + 2]-photocycloaddition/thermal fragmentation approach toward 5-8-5 ring systems

[reaction: see text]. An intramolecular [2 + 2]-photocycloaddition is used to provide a photoadduct, which upon fragmentation, lactone cleavage, and subsequent Cope rearrangement provides a dicyclopenta[a,d]cyclooctene ring system with substituents in place (e.g., C3 and C11) to access several 5-8-5 diterpene and sesterterpene natural products.     

Novel reaction pathways for 2-pyridone [4+4] photoadducts

[Structure: see text] Transannular ring closure of a pyridone-furan [4+4] photoadduct has been evaluated in a model system. A combination of nitrogen substitution and an isopropyl group gave full control of the four new stereogenic centers. Chlorination transformed the 1,5-cyclooctadiene to a [4.2.0] ring system instead of to the expected [3.3.0] ring system. Changing an alkene to an enone suppressed this pathway and led to a new rearrangement, converting the 5-8-5 ring system to a 6-7-5 system.     

Vibrational dynamics of deoxyguanosine 5'-monophosphate following UV excitation

The relaxation dynamics of the DNA nucleotide deoxyguanosine 5'-monophosphate (dGMP) following 266 nm photoexcitation has been studied by transient IR spectroscopy with femtosecond time resolution. The induced dynamics of the amide I (carbonyl) stretch, the asymmetric guanine ring stretch and the phosphate asymmetric stretch are monitored in the region 1000-1800 cm(-1). Excitation and subsequent rapid internal conversion to a "hot" ground state is reflected by depletion of the vibrational ground states of the amide I stretch and guanine ring stretch. However, the vibrational ground state of the phosphate is left unperturbed, indicating the absence of vibrational coupling between the guanine ring system and the phosphate group. The vibrational ground state of the amide I is repopulated in 2.5 ps (±0.2 ps) while it takes 3.7 ps (±0.5 ps) to repopulate the guanine ring vibration. This article discusses two possible relaxation pathways of dGMP, as well as the implications of the weak phosphate dynamics.     

N,N′-二[3-氯-5S-(l-孟氧基)-2(5H)-4-呋喃酮基]-1,4-丁二胺的合成及晶体结构(英文)

合成了N,N′-二[3-氯-5S-(l-孟氧基)-2(5H)-4-呋喃酮基]-1,4-丁二胺,并通过IR,1H NMR,MS和X射线单晶衍射对其进行了表征.X射线单晶衍射结果表明:标题化合物的不对称结构单元中包含一个平面的呋喃酮环和一个椅式的环己烷环,四个手性中心.标题化合物通过N—H…O分子间氢键作用实现空间堆积.     

A five-membered Ru5 ring in a hexagonal La14 cage: the La14Cl20Ru5 structure

The title compound features a five-membered Ru(5) ring embedded in a La(14) hexagonal wheel-like cage, an incommensurate combination of the two building units. A formal electron partition of (La(3+))(14)(Cl(-))(20)(Ru(5))(22-) results in a (Ru(5))(22-) ring isoelectronic to (Cd(5))(2-). However, computational studies show that there is significant electron back-donation from the Ru(5) ring to the La(14) wheel. This interaction strongly stabilizes the Ru(5) ring. The resistivity and magnetic susceptibility of the compound have also been investigated.     

A novel biomimetic route to the 3-acyl-5-hydroxy-3-pyrrolin-2-one and 3-acyl-3,4-epoxy-5-hydroxypyrrolidin-2-one ring systems

Modified Moffat oxidation of alcohols 17, 22, and 25 afforded aldehydes that underwent intramolecular aldol reactions on treatment with a NaOH solution to yield 4-pyrrolin-2-ones 16, 23, and 26. Oxidation with DMDO at -40 degrees C provided 3-acyl-5-hydroxy-3-pyrrolin-2-ones 18, 24, and 27 with the ring system of oteromycin (3), UCS1025A (5), and related natural products. Further oxidation of 18 yielded 3-acyl-3,4-epoxy-5-hydroxy-pyrrolidin-2-one 19 with the ring system of fusarin C (1) and epolactaene (2). Dehydration of 18 afforded 20 with the talaroconvolutin A (4) ring system.