Asymmetrical oxidation of menthone dithiolane

Asymmetrical oxidation was performed of menthone dithiolane obtained in 95–98% yield by condensation of menthone with 1,2-ethanedithiol in the presence of boron trifluoride etherate. 6-Isopropyl-9-methyl-1,4-dithiaspiro[4,5]decane-1,4-dioxide (yield 5–55%) and 6-isopropyl-9-methyl-1,4-dithiaspiro[4,5]-decane-1,1,4-trioxide (yield 65–70%) were synthesized. Chemical structures of compounds obtained were proved by XRD analysis, NMR and IR spectroscopy.     

Correlation between C and O chemical shifts and torsional strain in spiroacetals

The relationship between the ¹³C and ¹⁷O NMR chemical shifts and the dihedral energies (non-bonding interactions) of 1,4-dioxaspiro[4.4]nonane, 1,4-dioxa- and 6,10-dioxaspiro[4.5]decane, 1,4-dioxa- and 6,11-dioxaspiro[4.6]undecane, 1,5-dioxaspiro[5.5]undecane, 1,5-dioxa and 7,12-dioxaspiro[5.6]dodecane and 1,6-dioxaspiro[6.6]tridecane were analyzed. These data showed correlation of the non-bonding interactions with the chemical shift of the spiranic carbon, as well as a linear relationship between ¹³C and ¹⁷O.     

Synthesis of sulfur‐containing heterocycles: spiropyrimidinetriones,thioxopyrimidinediones, pyrazolidinediones,and isoxazolidinediones—part ii

1‐Aroyl‐2‐styrylsulfonylethene is the precursor for 4,4‐dimethoxycarbonyl‐2′,5‐diaryl‐3‐(1′,3′‐dioxolano)‐1‐thia‐1,1‐dioxide ( 4 ), which is the key intermediate for the synthesis of 7‐aroyl‐11‐aryl‐2,4‐diazaspiro[5,5]undecane‐1,3,5‐trione‐9‐thia‐9,9‐dioxide( 10 )/3‐thioxo‐1,5‐dione‐9‐thia‐9,9‐dioxide ( 11 ), 6‐aroyl‐10‐aryl‐2,3‐diazaspiro[4,5]decane‐1,4‐dione‐8‐thia‐8,8‐dioxide ( 12 )/2‐oxo‐3‐azaspiro [4,5]decane‐1,4‐dione‐8‐thia‐8,8‐dioxide ( 13 ). The new compounds were characterized by IR and ¹H NMR spectral data. © 2001 John Wiley & Sons, Inc. Heteroatom Chem 12:131–135, 2001     

Influence of molecular structure on the liquid-crystalline properties of 1,5-dihetero-spiro[5.5]undecane- and -dispiro[5.2.5.2]hexadecane derivatives

Abstract

The synthesis and liquid-crystalline properties of 1,5-dioxa- and 1,5-dithiaspiro[5.5]undecane, 7,16-dioxa-dispiro[5.2.5.2]hexadecane and 1,5,10,14-tetraoxa-dispiro[5.2.5.2]hexadecane derivatives are described. The effects of terminal sub-stituents and molecular structure on the liquid-crystalline properties of these materials are discussed.     

Influence of molecular structure on the liquid-crystalline properties of 1,5-dihetero-spiro[5.5]undecane- and -dispiro[5.2.5.2]hexadecane derivatives

The synthesis and liquid-crystalline properties of 1,5-dioxa- and 1,5-dithiaspiro[5.5]undecane, 7,16-dioxa-dispiro[5.2.5.2]hexadecane and 1,5,10,14-tetraoxa-dispiro[5.2.5.2]hexadecane derivatives are described. The effects of terminal sub-stituents and molecular structure on the liquid-crystalline properties of these materials are discussed.     

A concise route to the C2-symmetric tricyclic skeleton of ryanodine

Ryanodine is a potent calcium channel modulator. In this Letter, we report the 10-step synthesis of the highly substituted tricyclic ring system of ryanodine. Diels-Alder reaction via dearomatization of 2,5-dimethylbenzene-1,4-diol and subsequent SmI₂-mediated reductive coupling of eight-membered 1,5-diketone efficiently introduced the four consecutive fully substituted carbons of the tricyclo[3.3.2.0^2,6]decane system.     

Conformational analysis of mesocyclic polythioethers : Gas phase conformational analysis of five mesocyclic polythioethers using photoelectron spectroscopy

The helium I photoelectron spectra of the mesocyclic polythioethers 1,4-dithiacycloheptane (1,4-DTCH), 1,5-dithiacyclooctane (1,5-DTCO), 1,5-dithiacyclononane (1,5-DTCN), 1,4,7-trithiacyclononane (1,4,7-TTCN), and 1,6-dithiacyclodecane (1,6-DTCD) are reported. The conformations of these molecules in the gas phase are deduced from correlations of the observed spectra with semi-empirical MO calculations, as well as molecular mechanics analysis.     

The cleavage mechanism of 1,4-dithiaspiro(4.4)nonane by gas-phase pyrolysis

The initial product formed in the pyrolysis of 1,4-dithiaspiro(4.4)nonane (I) is the thioketone (7). During pyrolysis at 600 °C, this material has been isolated in absolute yields as high as 4.85%. The increase in yield of benzene (1), toluene (3), and naphthalene (14) as the temperature is increased from 600 to 800 °C could be anticipated from dehydrogenation under pyrolysis conditions.The other products isolated, with the exception of the rearrangement products and toluene, appear to arise via further pyrolytic reaction of thioketone (7). These saturated products are dehydrogenated by sulfur to generate the aromatic compounds.     

Synthesis and structural characterization of new stiff rod oligomeric domains by X-ray crystallography and NMR

The monomers N,N'-dibenzylbenzene-1,4-diamine (1), N,N'-dibenzylnaphthalene-1,5-diamine (2), and N,N'-dibenzylanthracene-1,9-diamine (3) were reacted with phosgene in the presence of a base to produce the corresponding N,N'-dibenzyl-1,4-bis(chlorocarbonylamino)benzene (4), N,N'-dibenzyl-1,5-bis(chlorocarbonylamino)naphthalene (5), and N,N'-dibenzyl-9,10-bis(chlorocarbonylamino)anthracene (6). These monomers were used to create zigzag type stacks, in a stepwise fashion, of trimers and 9-mers of either 1,4-diureidobenzenes ((Phe)K(3) and (Phe)K(9)) or 1,5-diureidonaphthalenes ((Nap)K(3) and (Nap)K(9)). A byproduct in the formation of (Phe)K(9) was a cyclic hexamer (Phe)K(6). NMR gave evidence of the structure in solution while X-ray crystallographic information was obtained for 5, 6, (Nap)K(3), and the cyclic (Phe)K(6).     

Total synthesis of the novel tricyclic sesquiterpene sulcatine G

A synthetic approach to the tricyclic sesquiterpene sulcatine G, 2, bearing a novel tricyclo[6.2.0.2(2,6)]decane framework, from commercially available 1,5-cod and leading to the first total synthesis of the natural product is described.     

In Process Citation

The behaviour of two organic compounds, 1,5-di[2-furyl]-1,4-pentadien-3-one (DFPO) and 1,5-di[2-thienyl]-1,4-pentadien-3-one (DTPO), as acid-base indicators has been studied by plotting the curves A = f(lambda) in the presence of various concentrations of perchloric acid, in anhydrous acetic acid medium. The values of pK(i)(HClO(4))) have been determined by spectrophotometry. The efficiency of these indicators in visual and colorimetric detection of the end-points of acid-base titrations has been examined.     

Synthesis of oxa-aza spirobicycles by intramolecular hydrogen atom transfer promoted by N-radicals in carbohydrate systems

The nitrogen-centred radical generated by reaction of an N-phosphoramidate or N-cyanamide, attached to a tri- or tetramethylene tether extended from the C-1 of a carbohydrate, with (diacetoxyiodo)benzene (DIB) and iodine can undergo a regio- and stereoselective intramolecular hydrogen atom transfer (HAT) reaction to furnish four different oxa-azaspirobicyclic systems: 1-oxa-6-azaspiro[4.4]nonane, 1-oxa-6-azaspiro[4.5]decane, 6-oxa-1-azaspiro[4.5]decane and 1-oxa-7-azaspiro[5.5]undecane. A tandem 1,5- or 1,6-HAT-oxidation-nucleophilic cyclisation mechanism is proposed.     

Theoretical calculation of the vibrational spectra of cis-cis-cyclooctadienes in the vapour phase

The theoretical infrared spectra of 1,3-cis-cis-cyclooctadiene (1,3-COD) and 1,5-cis-cis-cyclooctadiene (1,5-COD), were obtained by ab initio MO calculations at Hartree-Fock level. The results were compared with the available IR experimental spectra of 1,3- and 1,5-COD. The apparent agreement between theoretical and experimental data allows us to exploit two bands, found only in the case of the theoretical spectrum of 1,4-COD, as a tool for identifying 1,4-COD during its synthesis.     

Oxidation of 2-Chloro-1-phenylethane-1,1-dithiol

Oxidation of 2-chloro-1-phenylethane-1,1-dithiol with bromine, iodine, and elemental sulfur, as well as under UV irradiation, leads to formation of 1,4-bis(chloromethyl)-1,4-diphenyl-2,3,5,6-tetrathiane in 50–95% yield. Oxidation of the same substrate with selenium dioxide gives 1,5-bis(chloromethyl)-1,5-diphenyl-2,4-dithia-3-selenapentane-1,5-dithiol. On heating to 60°C, the latter loses selenium to afford 1,4-bis-(chloromethyl)-1,4-diphenyl-2,3-dithiabutane-1,4-dithiol.     

Structure–property relationships of novel fluorinated polycarbonate polyurethane films with high transparency and thermal stability

Research on Chemical Intermediates - Novel polycarbonate diol (PCDL) was synthesized using dimethyl carbonate, 1,5-pentanediol (1,5-PD), 1,6-hexanediol (1,6-HD) and 1,4-cyclohexanedimethanol...     

Structural diversity of interaction products of mucochloric acid and its derivatives with 1,2-ethanedithiol

The synthesis and characterization of previously unknown sulfur-containing products from the reaction of mucochloric acid (3,4-dichloro-5-hydroxy-2(5H)-furanone) and its 5-alkoxy derivatives with 1,2-ethanedithiol is reported. Under basic and acidic conditions both SH-groups of the reagent show nucleophilic activity, leading to the formation of substitution products of different structural types. Novel fused (7-hydroxy-2,3-dihydro[1,4]dithiino[2,3-c]furan-5(7H)-one) and spiro (9-chloro-6-methoxy-7-oxa-1,4-dithiaspiro[4.4]nonan-8-one) bicyclic compounds, as well as various bis-thioethers have been obtained and characterized by NMR spectroscopy and single crystal X-ray diffraction.     

Determination of water soluble imidazo-1,4-benzodiazepines in blood by electron- capture gas--liquid chromatography and in urine by differential pulse polaragraphy.

A sensitive and specific electron-capture gas--liquid chromatographic (GLC--ECD) assay was developed for the determination of 8-chloro-6-(2'-fluorophenyl)-1-methyl-4H-imidazo(1,5a)(1,4)benzodiazepine (I) or 8-chloro-1,4-dimethyl-6-(2'-fluorophenyl)-4H-imidazo (1,5a)(1,4)benzodiazepine (II) in blood. The assay for both compounds involves extraction into benzene--methylene chloride (9:1) from blood buffered to pH 12.6 The overall recovery of I and II from blood is 86% +- 5.0 (S.D.) and the sensitivity limit of detection is of the order of 2 to 3 ng of I or II per milliltre of blood. The major urinary metabolite of I is 8-chloro-6-(2'-fluorophenyl)-1-hydroxymethyl-4H-imidazo(1,5a)(1,4)benzodiazepine, (IA) present as a glucuronide conjugate while 8-chloro-6-(2'-fluorophenyl)-4-hydroxyl-1-methyl-4H-imidazo(1,5a)(1,4)benzodiazepine, (IB) and 8-chloro-6-(2'-fluorophenyl)-4-hydroxy-1-hydroxymethyl-4H-imidazo(1,5a)(1,4) benzodiazepine, (IC) are minor metabolites. The major metabolite IA is extracted into benzene--methylene chloride (9:1) from urine buffered to pH 11.0 (after incubation with glucuronidase--sulfatase as pH 5.0), and analyzed by differential pulse polarography (DPP) in 0.1 M phosphate buffer PH 3). The overall recovery of IA is 84 +- 3.0% (S.D.) with a sensitivity limit of 50 ng per millilitre of urine. The metabolites of compound II have not as yet been elucidated. The GLC--ECD and DPP assays were applied to the determination of blood levels and urinary excretion in dogs following single 10 mg/kg intravenous and oral doses of I and following single 6 mg/kg intravenous and 10 mg/kg oral doses of II. Blood levels of compound I were also evaluated in man following intravenous infusion of single 10 mg doses.     

Enantiomerically pure rhodium complexes bearing 1,5-diphenyl-1,5-cyclooctadiene as a chiral diene ligand. Their use as catalysts for asymmetric 1,4-addition of phenylzinc chloride

[reaction and structures: see text] A rhodium complex coordinated with 1,5-diphenyl-1,5-cyclooctadiene (Ph-cod), [RhCl((R)-Ph-cod)]2, was obtained enantiomerically pure through optical resolution of diastereomeric isomers [Rh(Ph-cod)((R)-1,1'-binaphthyl-2,2'-diamine)]BF4. The enantiomerically pure rhodium complexes showed high catalytic activity and enantioselectivity (up to 98% ee) in the asymmetric 1,4-addition of phenylzinc chloride to alpha,beta-unsaturated ketones and esters in the presence of chlorotrimethylsilane.     

Quinazolincs and 1,4-benzodiazepines. LXXXVI. The synthesis of imidazothienodiazepines and imidazopyrazolodiazepines

The thieno[3,2-e][1,4]diazepin-2-one ( 1a ), the thieno[2,3-e] [ 1,4] diazepin-2-one ( 1b ), the pyrazolo[3,4-e][1,4]diazepin-2-one ( 1c ) and a chloro analog of 1b , compound 1d , were each converted to derivatives of the novel tricyclic ring systems 4H-imidazo[1,5-a]thieno[2,3-f] [1,4]-diazepine, 4Himidazo[1,5a]thieno[2,3f][1,4]diazepine and 4H-imidazo[ 1,5-a]pyrazolo[4,3-f]-[1,4]diazepine. Depending on the substituents desired on the imidazo ring, two different synthetic pathways were employed.     

Über den Mechanismus der Cope-Umlagerung

On the Mechanism of the Cope Rearrangement The rates of the Cope rearrangement of 2,5-dicyano-3-methyl-hexa-1, 5-diene ( 12 ), (E)- and (Z)-2, 5-dicyano-hepta-1,5-diene ((E)- and (Z)- 14 ) as well as of 2, 5-dimethoxycarbonyl-3-methyl-hexa-1,5-diene ( 13 ) and (E)- and (Z)-2,5-dimethoxycarbonyl-hepta-1,5-diene ((E)- and (Z)- 15 ) were measured in decane solution in the temperature range of 50 to 150° (see Tables 5 and 8 to 12). A detailed English summary of this work is given in [1 b].