bluuebunny/crossref_metadata_2025 huggingface dataset:
The Synthesis and Application of Novel Nitrating and Nitrosating Agents
Authors: Hakimalahi Gholam H. , Sharghi Hashem , Zarrinmayeh Hamide , Khalafi‐Nezhad Ali
Published: December 2004

Alcohols and phenols are efficiently nitrated with thionyl chloride nitrate or thionyl nitrate, even in the presence of an aromatic moiety. While thionyl chloride nitrate is suitable for nitration of primary OH‐groups in carbohydrates, thionyl nitrate is reactive enough to react with secondary OH‐groups as well. These reagents permit the highly selective nitration of the 5′‐,2′5′‐ and 3′, 5′‐OH‐groups of ribonucleosides to produce either mono‐or diprotected nitro derivatives in high yields. Carbon acids and the enol form of some ketones are efficiently nitrated with trifluoromethanesulfonyl nitrate/potassium tert‐butoxide. Lutidine N‐oxide (2,6‐(CH3)2C5H3N O) was found to have a marked effect on nitration reactions. Similarly, thionyl chloride nitrite and thionyl nitrite exhibit an excellent capacity for nitrosation of the aforementioned substrates.
1,2‐Epoxycarotinoide. 3. Mitteilung. Isolierun von 1,2‐Epoxy‐1,2‐dihydrolycopin aus Tomaten
Authors: Berset Daniel , Pafander Hansperter
Published: December 2004

1,2‐Epoxycarotenoids: Isolation of 1,2‐Epoxy‐1,2‐dihydrolycopene from Tomatoes

The optically active, 1,2‐epoxy‐1,2‐dihydrolycopene was isolated from tomatoes. Its constitution was established by comparison with the racemic synthetic compound.
Plectranthone A, B, C und D. Diterpenoide Phenanthren‐1,4‐dione aus Blattdrüsen einer Plectranthuus sp. (Labiatae)
Authors: Alder Alfredo Carlos , Rüedi Peter , Eugster Conrad Hans
Published: December 2004

Plectranthons A, B, C, and D. Diterpenoid Phenanthrene‐1,4‐diones from Leaf‐glands a Plectranthus sp. (Labiatae)

The following structures of four new 1,4‐phenanthraquionones, isolated in minute amounts from the coloured leaf‐glands of a Plectranthus sp. obtained from the borders of Lake Kiwu2, Rwanda, are proposed: plectranthon A (1; 3‐hydroxy‐5, 7,8‐trimethyl‐2‐(2‐propenyl)phenanthrene‐1, 4‐dione), plectranthon B (2; 2‐(2ξ‐acetoxypropyl)‐3‐hydroxy‐5,7,8‐trimethylphenanthrene‐1,4‐dione), plextranthon C (3; 3‐hydroxy‐ 7,8‐diemethyl‐2‐(2‐propenyl)phenanthrene‐1,4‐dione), and plectranthon D (4; 3‐hydroxy‐7,8,10‐trimethyl‐2‐(2‐propenyl)phenanthrene‐1,4‐dione). 2‐(2ξ‐Hydroxypropyl)‐3,6‐dihydroxy‐5,7,8‐trimethylphenanthrene‐1,4‐dione (11), a compound very similar to 1–4, was prepared by a Wagner‐Meerwein, rearrangement of coleon E (5). Biogenetically, the plectranthons are derived from abietanoic precursors. The compounds 1, 2 and 4 are the first natural C20‐phenanthrenes of diterpenoid origin.
Stabilities and Redox Properties of Cu(I) and Cu(II) Complexes with Macrocyclic Ligands Containing the N2S2 donor Set
Authors: Balakrishnan Karappulli P. , Kaden Thomas A. , Siegfried Liselotte , Zuberbühler Andreas D.
Published: December 2004

The complexation of Cu(I) and Cu(II) by a series of 12‐, 14‐ and 16‐membered macrocyclic ligands 1–6 containing the N2S2 donor set has been studied potentiometrically, spectrophotometrically and voltammetrically.

In the case of Cu(II), mononuclear complexes CuL2+ with stability constants of 1010–1015 are formed. In addition, partially hydrolyzed species Cu(L)OH+ are observed at pH > 10 for the 12‐membered ligands. For Cu(I), beside the specis CuL+ with stabilities of 1012–1014, the unexpected formation of protonated species CuLH2+ was detected. In contrast to the well‐known general trends in coordination chemistry, the stability of these protonated species increases relative to that of the complexes with the neutral ligand when the ring size and concomitantly the distance between neighbouring donor atoms is decreased. From the stability constants of the Cu(I)‐ and Cu(II)‐complexes the redox potentials have been calculated and are compared to the values of E1/2 obtained by cyclic voltammetry. Despite the identical donor set the Cu(II)/Cu(I) redox potentials of the complexes are spanning a range of 340 mV or six orders of magnitude in relative stability, reflecting the importance of subtle differences in steric requirements.
Syntheses of (±)‐ and Enantiomerically Pure (+)‐Longifolene and of (±)‐ and Enantiomerically Pure (+)‐Sativene by an Intramolecular de Mayo Reaction
Authors: Oppolzer Wolfgang , Godel Thierry
Published: December 2004

Starting from 2‐cyclopentenoyl chloride ((RS)‐ or (S)‐8), the racemic as well as the enantiomerically pure (+)‐sesquiterpenes longifolene ((±)‐ and (+)‐1, resp.) and sativene ((±)‐ and (+)‐2, resp.) were synthesized efficiently by a sequence of nine and ten steps, respectively. The key sequence 10 → 16 → 3 is the first strategic application of an intramolecular photoaddition/retro‐aldolization sequence (intramolecular de Mayo reaction) in organic synthesis.
Cyclodopa glucoside ( = (2S)‐5‐(β‐D‐glocopyranosyloxy)‐6‐hydroxyindoline‐2‐carboxylic acid) and its occurrence in red beet (beta vulgaris var. rubra L.)
Authors: Wyler Hugo , Meuer Ursula , Bauer Jacques , Stravs‐Mombelli Luisa
Published: December 2004

Cyclodopa glucoside ( = (2S)‐5‐(β‐D‐glucopyranosyloxy)‐6‐hydroxyindoline‐2‐carboxylicacid; 1a) is prepared from betainin (2a) via a base exchange reaction. Its purification and physical properties are described. The compound is N‐formylated in dilute HCOOH solution. Cyclodopa glucoside is contained in considerable amount in redbeet juice varying from 0.07 to 1.9 mmol/kg or from 12 to 46% relative to teh content of betanin. Teh occurrence of free cyclodopa glucoside supports its role as intermediate in betanin biosynthesis.
Syntyhesis of 1,2,4,5‐Tetrazino[1,6‐a: 4,3‐a′]diquinoxaline
Authors: Koçak Ahmet , Berkâroǧlu ÖZer
Published: December 2004

A new one‐step synthesis of 2 (1H)‐quinoxalinone oxime (3) from (1,2‐benzenediamine (1) and s‐trans‐chloroethanedial dioxime (2) is described. This oxime is converted into a new heterocyclic compound, 1,2,4,5,‐tetrazino)[1,6‐a: 4,3‐a′]diquinoxaline (4), by the template effect of Co(II) and Ni(II) ions.
The chemistry of drugs part IV, Configurations of antimalarials derived from qinghaosu: Dihydroqingyhaosu, artemether, and artesunic acid
Authors: Luo Xuan‐De , Yeh Herman J. C. , Brossi Arnold , Flippen‐Anderson Judith L. , Gillardi Richard
Published: December 2004

The structures of the antimalarials dihydroqinghaosu (2), artemether (3), and artesunic acid (7a) derived from qinghaosu were elaborated by 1H‐NMR spectroscopy, and supported with X‐ray data obtained for 2 and 3. Several new derivatives, useful for the chemical characterization of dihydroqinghaosu (2) and artesunic acid (7a), were prepared.
The synthesis and transition temperatures of ester derivatives of 2‐fluoro‐4‐hydroxy‐ and 3‐fluoro‐4‐hydroxybenzonitriles also incorporating aliphatic ring systems
Authors: Kelly Stephen M. , Schad Hanspeter
Published: December 2004

The synthesis and liquid‐crystal transition temperatures of forty ester derivatives of 2‐fluoro‐4‐hydroxybenzonitrile and 3‐fluoro‐4‐hydroxybenzonitrile are reported. The esters contain the trans‐1,4‐disubstituted cyclohexane or the 1,4‐disubstituted bicyclo[2.2.2]octane rings (some contain an additional phenyl ring). Many of the novel F‐substituted esters exhibit substantially higher nematic‐isotropic transition temperatures than the corresponding unsubstituted esters. The order of clearing points of these laterally substiuted esters differing only in the presence of a benzene ring and the above‐mentioned rings id established.
An Example of Head‐to‐Head Dimerization of β4.4‐Helices
Authors: Lorenzi Gian Paolo , Muri‐Valle Valentina , Bangerter Felix
Published: December 2004

1H‐NMR and vapor‐pressure osmometry results are presented, which indicate the occurrence of a rapid equilibrium involving the head‐to‐head dimerization of β44‐helices in chloroform solutions of HCO‐L‐Ile‐(D‐AIle‐L‐Ile)4‐OMe. This equilibrium typifies the one that, in Urry's view, would be responsible for the formation and breaking down of the ion‐conducting channels formed by gramicidin A in lipid bilayers.
Further Syntheses of Optically Active Verrucarinic Acid, 43rd Communication of Verrucarins and Roridins
Authors: Grossen Peter , Herold Peter , Mohr Peter , Tamm Christoph
Published: December 2004

Two new syntheses of verrucarinic acid (2S, 3R‐dihydroxy‐3‐methylpentanoic acid) and its derivatives, suitably protected for the further conversion to macrocyclic trichothecenes, are described. The first one makes use of a diastereoselective alkylation of a (−)‐(S)‐malic acid ester and the regioselective reductin of one carboxyl function toa methyl group. The second approach involves a stereoselective addition of an allylsilane to a chiral glyoxylate.
Mechanismus der decarboxylativen Dimerisierung von Maleinsäureanhydrid zu Dimethylmaleinsäureanhydrid unter Einfluss von 2‐Aminopyridin
Authors: Baumann Marcus E. , Bosshard Hans , Breitenstein Werner , Rihs Grety , Winkler Tammo
Published: December 2004

Mechanism of the Decarboxylative Dimerization of Maleic Anhydride to Dimethylmaleic Anhydride under the Influence of 2‐Aminopyridine

The mechanism of the decarboxylative dimerization of maleic anhydride to dimethylmaleic anhydride was investigated. It was shwon that imidazo[1,2‐a] pyridines play an important role as intermediates in this rather unusual transformation, the key step being a Michael addition of 5 to maleic anhydride.
Novel Variant of the Tricyclooctanone Approach to Cyclopentanoid Natural Products. Synthesis of (±)‐Coriolin. Preliminary Communication
Authors: Demuth Martin , Ritterskamp Peter , Schaffner Kurt
Published: December 2004

A total synthesis of the antitumor sesquiterpene coriolin (9; racemic) in 11 steps from 3,3,6‐trimethylbicyclo[2.2.2]oct‐7‐ene‐2,5‐dione (2a/2b) is described (yield 2a/2b→8: 28%). The sequence is unprecedentedly short and avoids difficult separation problems. The key step in the scheme is a novel facet of oxadi‐π‐methane photochemistry, i.e., the steering by subtle steric effects of the β,γ‐unsaturated ϵ‐diketone to undergo a regioselective photorearrangement involving one β,γ‐enone partial chromophore. Furthermore, the overall phototransformation, which can be carried out at unusually high concentrations (≥20% solutions), involves also a Norrish type I process equilibrating the two epimeric starting enediones 2a and 2b in favour of the desired stereoisomer.
Cyclopropylidenebis(diphenylphosphine): Note on its Synthesis, Properties and Spectral Data
Authors: Schmidbaur Hubert , Pollok Thomas
Published: December 2004

The title compound has been synthesized through cyclopropanation of vinylidenebis(diphenylphosphine) using dimethylsulfoxonium methylide. It is easily converted into its dioxide and disulfide. NMR data of these first geminal diphosphinocyclopropanes are presented.
Nukleophile Reaktionen an 2‐Phenylindolenin‐3‐onen
Authors: Adam Jean‐Marie , Winkler Tammo
Published: December 2004

Nucleophilic Reactions on 2‐Phenylindolenin‐3‐ones

Nucleophilic reagents such as 4‐nitrophenylhydrazine, malonic acid derivatives, and hydrogen peroxide react with 2‐phenylindolenin‐3‐ones giving, in the first step, addition products to the (d) NC(2) bond. This addition can be reversible, but in most cases new rearrangement products are formed. The structure of the new compounds were elucidated by 1H‐ and 13C‐NMR spectroscopy.
Light‐Induced Synthesis of Thiolanes and 2,3‐Dihydrothiophenes by Addition of (E)‐4‐Mercapto‐2‐butenoates to Alkenes or Alkynes
Authors: Anklam Elke , Margaretha Paul
Published: December 2004

Irradiation (λ=300 mm) of methyl 4‐mercaptocrotonate (2a) in the presence of alkenes of alkynes affords methyl 3‐thiolaneacetates 7 and methyl 2,3‐dihydro‐3‐thiopheneacetates 13. The unsaturated heterocycles 13 undergo further light‐induced isomerization to methyl 2,3‐dihydro‐2‐thiopheneacetates 15. Both 13 and 15 are readily dehydrogenated to thiophenes 17 and 18, respectively.
Synthesis of Thiolanes from (E)‐4‐Mercapto‐2‐butenoates via, Consecutive Michael Additions
Authors: Anklam Elke , Margaretha Paul
Published: December 2004

Methyl 4‐mercaptocrotonate (4) adds to α,β‐unsaturated nitriles or carbonyl compounds in the presence of Triton B, as base. Several of the primary adducts (10) cyclize to thiolanes (11) in a second (base‐catalysed) Michael addition. Dimerization of 4 under these conditions affords a mixture of the diastereomeric 14‐dithianies 7 and 8.
Deoxy‐nitrosugars. 9th communication. Chain elongation of 1‐C ‐nitroglycosyl halides by substitution with some weakly basic carbanions
Authors: Aebischer Bernrd , Meuwly Roger , Vesella Andrea
Published: December 2004

The 1‐C‐nitroglycosyl chloride reacted with the anions form 2‐nitropropane, nitromethane, and diethyl malonate, to give the chain‐extended products 2 (81%), 5 (72%), and 6 (83%), respectively. Treatment of the 1‐C ‐nitroglycosyl bromide 7 by the lithium salt obtained form 8 gave the dodecodiulose derivative 9 (76%). Th β‐D‐configuration of 2 and 9 was inferred form their NMR and CD spectra. Treatment of 2 and 9 with sodium sulfide gave the enol ethers 3 (96%) and 10 (92%), respectively. The (Z)‐configuration of 10 was deduced form the configuration of its hydrogenation product 11.
Planarisation of Tetracoordinate Carbon Atom. A Further Route ot (all‐cis)‐[5.5.5.5]Fenestrane
Authors: Luyten Marcel , Keese Reinhart
Published: December 2004

The synthesis of (all‐cis)‐[5.5.5.5]fenestrane (3) from dicyclopentadiene is reported. Key step is the Pd‐catalyzed reductive deoxygenation of an appropriately substituted cyclooctanone, which leads to transannular C,C‐bond formation.
A New Approach to 1,2,4‐Trioxanes form Cyclic Allylic Hydroperoxides
Authors: Jefford Charles W. , Jaggi Danielle , Kohmoto Shigeo , Boukouvalas John , Bernardinelli Gérald
Published: December 2004

Summary The reaction of 4,5‐dimethyl‐4‐hydroperoxy‐1(4H)‐nephthalenone (9) with acetaldehyde, pivalaldehyde, benzaldehyde, and p‐chlorobenzaldehyde in CH2Cl2 in the presence of Amberlyst‐15 as catalyst gave the corresponding cis‐3‐methyl, t ‐butyl, phenyl and p ‐chlorophenyl derivatives of 10,10b‐dimethylnaphtono[2,1‐e][1,2,4]trioxin‐6(5)H‐one in 80‐95% yields. Acetone reacted similarly with 9 to give the 3,3′ ‐dimethyl derivative. Configurations of all trioxinones were assigned by comparison of their spectral properties with that of the p ‐chloro derivative whose structure was determined by X‐ray. 2,5‐Diphenyl‐2‐hydroperoxypyrrole was less efficient that 9, but it condensed with acetaldehyde and pivaladehyde under the same conditions giving the cis ‐ 3‐methyl and cis ‐ 3‐(t ‐butyl) derivatives of 6,7a‐diphenyl‐4a, 7a‐dihydro‐3H, 5H ‐[1,2,4]trio‐xino[3,2‐e]pyrrole in 24 and 20% yield, respectively.
Cyclic Octa‐ and Decapeptides as Ionophores for Magnesium
Authors: Behm Felix , Ammann Daniel , Simon Wilhelm , Brunfeldt Kay , Halstrøm John
Published: December 2004

Cyclic octa‐ and decapeptides have been prepared, and their ion selectivity in solvent polymeric membranes was studied. Cyclo(‐LPro‐DLeu‐)5 behaves as an ionophore which selects Mg2+ over Ca2+ by a factor of 100. Cyclo(LPro‐LLeu)5 induces selectivity in membranes for Mg2+ over Li+, Na+ and K+ by a factor of 400, 200 and 10, respectively, while selectivity of Mg2+ over Ca2+ is poor. Some evidence is presented which indicates that certain ionophores exhibit high selectivity for monovalent magnesium complexes.
Skeletal Migrations Observed during the Cob(I)alamin‐Catalyzed Reduction of 4β‐(tert‐Butyl)‐1β‐(1‐methylvinyl)cyclohexanecarbaldehyde
Authors: Ziegler Carl B. , Fischli Albert
Published: December 2004

During the cob(I)alamin(1(I))‐catalyzed reduction of 3, intermediate formation of 2 and final generation of 4–10 was observed (see Scheme 1, cf. Tables 1 and 2). Identical products in similar ratios were generated starting from either 2 or 3. Accepting the intermediate formation of six interconnected cobalt complexes, i.e. A–F (cf. Scheme 2), the generation of all the products observed can be explained.
The crystal structure of racemic and meso‐diastereoisomers of aqua[2,6‐bis(3‐carboxy‐1,2‐dimethyl‐2‐azapropyl)pyridine]‐Co(III) · Hexafluorophosphate · Di‐ and monohydrate, respectively
Authors: Stoeckli‐Evans Helen , Brehm Lotte , Pousaz Philippe , Bernauer Klaus , Bürgi Hans‐Beat
Published: December 2004

Synthesis of the pentadentate ligand 2,6‐bis(3‐carboxy‐1,2‐dimethyl‐2‐azapropyl)pyridine yields a mixture of the racemic and meso‐isomers which it was difficult to separate by column chromatography. When the cationic Co(III)‐complex of this ligand was crystallized with hexafluorophosphate as anion, two distinct crystalline forms were produced. The complex of the racemic ligand, 1, has C2 symmetry and is a dihydrate; a = 8.999(8), b = 12.047(6), c = 20.65(1) Å, orthorhombic, space group Peen,Z = 4, R = 0.074 for 1439 observed reflections. The complex of the meso‐ligand, 2, shows two independent molecules (2A and 2B) per asymmetric unit, both monohydrates with a resolved disordered H2O molecule in 2A; a = 10.109(4), b = 12.835(2), c = 16.651(3) Å, α = 89.5(1)°, β = 84.7(3)°, γ = 88.6(3)°, triclinic, space group P1, Z = 4, Rs = 0.054 for 4198 observed reflections. The coordination around the Co‐atom is distorted octahedral in both complexes, with the coordinated H2O molecule trans to the pyridine N‐atom. In the racemic form of the complex, 1, the pyridine ring is twisted about the Co‐N(1) bond with respect to the plane defined by atoms Co, N(1), O(W1), N(2) and N(2P) by 17.2(2)°. In the meso‐form of the complex, 2, the CH3 substituent C(8P) on atom C(4P), is now axial with respect to the 5‐membered chelate ring. As a result of steric hinderance between atom O(1) and CH3(8P), the pyridine ring has been displaced from the best mean‐plane formed by atoms Co, O(W1), N(2) and N(2P). The principal axis of the pyridine ring C(3)…N(1), makes an angle of 14.1(1)° (mean) with this plane. At the same time the pyridine ring is twisted about axis C(3)…N(1) with respect to this plane by 19.7(1)° (mean).
β‐Funktionalisierte Hydrazine aus N‐Phthalimidoaziridinen und ihre hydrogenolytische N,N‐Spaltung zu Aminen
Authors: Egli Markus , Hoesch Lienhard , Dreiding André S.
Published: December 2004

β‐Functionalized Hydrazines from N‐Phthalimidoaziridines and their Hydrogenolytic N,N‐Cleavage to Amines

The three N‐phthalimido‐aziridines 1–3 were reacted with phenol, thiophenol, aniline, p‐toluenesulfonic acid, and H2O in selected combinations. These nucleophiles opened the 3‐membered ring to yield the N‐phthalimidoamines 4a–d, 5a–d, 6a–c, and 6e; all these products (except the carbinol 6e) carry an aryl‐substituted functional group on the C‐atom vicinal to the N‐substituent. Hydrazinolysis of 4, 5, 6a–c, and 6e afforded the β‐functionalized hydrazines 7, 8, 9a–c, and 9e. The reducing medium Raney‐Ni/N2H4 transformed 4, 5, 6a–c, and 6e to the β‐functionalized amines 10, 11, 12a–c, and 12e. By a study with the hydrazide 6a and the hydrazine 9a, it was shown that the N,N‐cleavage is a catalytic hydrogenolysis by H2 generated from N2H4 with Raney‐Ni and that it does not take place on the hydrazide 6, but rather on the hydrazine 9, generated as intermediate from 6 with N2H4. Spectroscopic data confirmed that the conversions of 1–3 to 4–6 occurred exclusively with inversion and that the resulting configurations remained fully intact during the transformations of 4, 5, and 6 (via 7, 8, and 9) to 10, 11, and 12, respectively.
Stereoselective glycosylation of Alcohols and Silyl Ethers Using Glycosyl Fluorides and Boron Trifluoride Etherate
Authors: Kunz Horst , Sager Wilfried
Published: December 2004

The stereoselective glycosylation of alcohols and their silyl ethers has been achieved using O‐alkyl‐, O‐acyl‐, and acetal‐protected glycosyl fluorides of the pyranose and furanose series and boron trifluoride etherate in CH2Cl2.
Disproof of the Overall Enzymatic Biosynthesis of Vindoline from Tryptamine and Secologanin by Cell‐Free Extracts from the Leaves of Catharanthus roseus (L.) G. DON
Authors: Stöckigt Joachim , Gundlach Heidrun , Deus‐Neumann Brigitte
Published: December 2004

A cell‐free extract, which was isolated from the leaves of mature Catharanthus roseus plants by a previously published procedure, does not convert a mixture of secologanin and radiolabelled tryptamine to vindoline, as was recently claimed. The radioactivity in the purified alkaloid extract determined by earlier workers is certainly due to ‘impurities’ in the presumed ‘vindoline’. This was shown by extensive purification of the alkaloid extract (which contained added unlabelled vindoline as a carrier) followed by chemical conversion of vindoline to two derivatives and subsequent purification, ultimately giving unlabelled deacetylvindoline.
The Molecular Ion of 5‐Methylene‐1,3‐cyclohexadiene: Electronic Absorption Spectrum and Revised Enthalpy of Formation
Authors: Bally Thomas , Hasselmann Dieter , Loosen Klaus
Published: December 2004

The title compound (1) is prepared in situ from 5‐methylenebicyclo[2.2.0]hex‐2‐ene by pyrolysis and subsequent photoionization in a photoelectron spectrometer or by X‐ray irradiation in an Ar matrix where its electronic absorption spectrum is obtained. The results confirm earlier conjectures that the title cation exists as a distinct entity on the C7H8+ hypersurface and can be obtained photochemically from other isomeric ions or by a McLafferty rearrangement. The enthalpies of formation of 1, its precursor and the corresponding radical ions are compared to the most recent data available for other C7H8 isomers and their ions. It is shown that the thermodynamic stability of 1+ is closer to that of toluene cation than concluded on the basis of earlier results.
The Structures of Some Products from the Photodegradation of the Pluramycin Antibiotics Hedamycin and Kidamycin
Authors: Fredenhagen Andreas , Séquin Urs
Published: December 2004

The photolability of the antitumor antibiotic hedamycin (1) was investigated by irradiation in different solvents in the presence or in the absence of oxygen. The products formed were separated chromatographically and their structures determined by NMR spectroscopy. Photolysis of 1 in the presence of oxygen gave only one isolable product, photohedamycin A (3), where ring E of hedamycin had been transformed into an enol ether. The reaction in the absence of oxygen yielded the photohedamycins B, C, and D (5, 6, and 7, respectively). In these compounds, one of the epoxides of hedamycin had been opened reductively, and in photohedamycin D (7) the substituent at C(8) ‐ originally ring E of hedamycin ‐ was now acyclic. In addition to these compounds, the photolyses yielded a large number of unstable minor products, which could not be isolated.
First Optically Active Heptalenes and their Absolute Configuration
Authors: Bernhard Werner , Brügger Paul , Daly John J. , Schönholzer Peter , Weber Roland H. , Hansen Hans‐Jürgen
Published: December 2004

It is shown that dimethyl 7‐isopropyl‐5, 10‐dimethylheptalene‐1, 2‐dicarboxylate (1) and dimethyl 5, 6, 8, 10‐tetramethylheptalene‐1, 2‐dicarboxylate (2) can be resolved via the corresponding mono‐acids and with the aid of optically active primary or secondary amines such as 1‐phenylethylamine or ephedrine into the (−)‐(P)‐ and (+)‐(M)‐enantiomeres, respectively. Characteristic for the (P)‐chirality of the heptalene π‐skeleton with C2 or pseudo‐C2 symmetry are two (−)‐CE's at the long wavelength region (450–300 nm) followed by at least one intense (+)‐CE at wavelengths about or below 300 nm. The absolute configuration of the heptalenes was correlated with the well‐established absolute configuration of (+)‐(R)‐ and (−)‐(S)‐1‐phenylethanol.
Nucleoside und Nucleotide. Teil 22. Synthese eines Tridecanucleosiddodecaphosphats, das die unnatürliche Base 2(1H)‐Pyrimidinon enthält
Authors: Altermatt Rolf , Tamm Christoph
Published: December 2004

Nucleosides and Nucleotides. Part 22. Synthesis of a Tridecanucleoside Dodecaphosphate Containing the Unnatural Base 2(1H)‐Pyrimidinone

The tridecanucleosid dodecaphosphate d(TpTpMpCpGpTpCpApApApApTpC incorporating the modified nucleoside 1‐(2′‐deoxy‐β‐D‐ribofuranosyl)‐2(1H)‐pyrimidione (Md,2) was synthesized using the triester method. The intermediates were the suitably protected trimer d(TpTpM) and the pentamer d(TpTpMpCpG). The latter was condensed with the protected octamer d(TpCpApApApApTpC) to yield the desired tridecanucleotide.
Spontane Öffnung des Pyrimidinringes in Pyrrolo[2,3‐d]pyrimidinen nach intramolekularer Acylierung
Authors: Rosemeyer Helmut , Kaiser Klaus , Seela Frank , Zabel Volker , Saenger Wolfram
Published: December 2004

Spontaneous Opening of the Pyrimidine Ring of Pyrrolo[2,3‐d]pyrimidines after Intramolecular Acylation

Phase‐transfer alkylation of 4‐methoxy‐2‐methylthio‐7H‐pyrrolo[2,3‐d]pyrimidine (2) with ethyl 3‐bromopropionate leads regioselectively to the ester 3a. After displacement of its methylthio group and saponification of the ester function, the acid 3e is obtained which can be transferred to the functionalized deazahypoxanthine 3f by either treatment with dry HBr/glacial AcOH or by nucleophilic displacement of the 4‐methoxide. Reaction of 3f with a H2O‐soluble carbodiimide results in an intramolecular acylation at N(1) by the activated ester; the intermediate 4 undergoes spontaneous hydroxylation and subsequent opening of the pyrimidine ring under formation of the pyrrolo[1,2‐a]pyrimidine derivative 6. Its structure was proved by X‐ray analysis. Subsequent deformylation of 6 in alkaline medium leads to the compound 7 in almost quantitative yield.
Facile Synthesis of 2′‐Deoxyribofuranosides of Allopurinol and 4‐Amino‐1H‐pyrazolo[3,4‐d]pyrimidine via Phase‐Transfer Glycosylation
Authors: Seela Frank , Steker Herbert
Published: December 2004

Phase‐transfer glycosylation of 4‐methoxy‐1H‐pyrazolo[3,4‐d]pyrimidine with the 2‐deoxyribofuranosyl chloride 9 formed the N(1)‐β‐nucleoside 10a as main product (39%). As by‐products the α‐D‐anomer 11a (7%) and the N(2)‐isomer 12a (18%) were isolated. Assignment of these isomers was made on the basis of their 1H‐ and 13C‐NMR spectra. Removal of the sugar‐protecting groups yielded the 4‐methoxy‐nucleosides 10b, 11b, and 12b, respectively. Nucleophilic displacement of the 4‐MeO‐group gave the 2‐deoxyribofuranosides 1–4 of allopurinol and 4‐amino‐1H‐pyrazolo[3,4‐d]pyrimidine.
The Electronic Structure of Dopamine. An ab initio Electrostatic Potential Study of the Catechol Moiety
Authors: van de Waterbeemd Han , Carrupt Pierre‐Alain , Testa Bernard
Published: December 2004

Electronic properties of dopamine were studied by the ab initio STO‐3G MO method. The molecular electrostatic potential (MEP) around the aromatic ring and the catechol group remains practically the same in 3,4‐dihydroxytoluene (a model compound) and in neutral dopamine examined in its two extended conformations, namely that found in the crystal (side‐chain and aromatic ring almost perpendicular) and the one corresponding to 2‐amino‐6,7‐dihydroxytetralin (6,7‐ADTN) (side‐chain and aromatic ring almost coplanar). In protonated dopamine and in dopamine hydrochloride, the electrostatic potential of the catechol moiety is overshadowed by the positive charge, but the main features remain discernible. The catechol moiety was examined in its two coplanar conformations containing a ‘flip‐flop H‐bond’. The electrostatic potential around the catechol moiety is quite complex, with alternating positive and negative maxima. At increasing distances above and away from the catechol moiety, only two peripheral maxima, one negative and one positive, remain perceptible. The ‘flip‐flop’ mechanism results in an approximate interchange of these two potential maxima, a fact which tends to level out the structural differences between the α‐ and β‐rotamer of dopamine. Based on these results and on the structure of rigid agonists, some pharmacophoric features of dopamine agonists are proposed.
Nature et stabilité des complexes métalliques de cryptands dinucléants en solution II. Polythiamacrotricycles et monocycles apparentés
Authors: Arnaud‐Neu Françoise , Almasio Marie‐Christine , Spiess Bernard , Schwing‐Weill Marie‐José , Sullivan Sally A. , Lehn Jean‐Marie
Published: December 2004

Nature and Stability of Some Metallic Complexes of Dinucleating Cryptands in Solution II. Polythiamacrotricycles and Related Monocyclic Subunits

The stability constants of the Cu2+ and Ag+ complexes of the cylindrical macrotricycle 1a (1,7,13,19‐tetraaza 4,16‐dioxa 10,22,27,32‐tetrathiatricyclo[17.5.5.5]tetratriacontane) have been determined by pH‐metry, as well as those of the Cu2+, Co2+, Zn2+, Cd2+, Pb2+, and Ag+ complexes of the monocyclic subunit 2a (1,7‐dimethyl‐1,7‐diaza 4,10‐dithiacyclododecane), in aqueous solutions (NaClO4) at 25°. In the Cu(II) systems, equilibria were reached slowly, and the results established by pH‐metry were confirmed by UV/VIS spectrophotometric studies. The tricycle 1a forms dinuclear cryptates with copper and silver, with overall stability constants log β210 (Cu2‐1a)4+ = 18.5, log β21‐2 (Cu2‐1a(OH)2)2+ = 4.8, log β210(Ag2‐1a)2+ = 23.0. Ag+ also forms a mononuclear (Ag‐1a)+ complex, with log β110 = 13.1, but no mononuclear species were detected in the Cu‐1a system. The absorption spectra of the bis‐Cu(II) complexes of 1a and 2a in aqueous medium, MeOH and propylene carbonate (PC) are given, as well as those, in MeOH and PC, of the bis‐copper complexes of the related monocycles 3 and 4 (1,7‐diaza‐4,10,13‐trithiacyclopentadecane and 1.10‐diaza 4,7,13,16‐tetrathiacyclooctadecane, respectively), and tricycle 5 with two benzyl groups in the lateral chains.

The complexing properties of the polyoxa‐ and polythia macrotricycles (Parts I and II of this series) are compared to those of other bis‐chelating ligands, the bicyclic bis‐tren and the monocyclic bis‐dien.
Aromatic Nucleophilic Substitution. Part 1. Regiospecific Substitution of the Nitro Groups in 3,5‐Dinitrophthalic‐Acid Derivatives
Authors: Fischer Walter , Kvita Vratislav
Published: December 2004

The regioselectivity of nucleophilic substitution of the nitro groups in 3,5‐dinitrophthalic anhydrides and 3,5‐dinitrophthalimides (Scheme) with a variety of nucleophiles (Nu−) was studied. In all cases, the 3‐nitro group was selectively substituted. With excess of the same nucleophilic reagent or with other nucleophiles, the 5‐nitro group could subsequently be replaced.
Inductive Charge Dispersal in Quinuclidinium Ions. Polar Effects, Part 13
Authors: Grob Cyril A.
Published: December 2004

Inductive charge dispersal to the α‐ β‐ and γ‐positions of the solvated quinuclidinium ion has been examined by comparing the pKa and the derived inductivities ρI of several 2‐ 3‐ and 4‐substituted quinuclidinium perchlorates 4, 5, and 6, respectively. The same inductivity is observed at the practically equidistant β‐ and γ‐positions. It, therefore, appears that polar substituent effects are transmitted directly through the molecule. As expected, inductivity is considerably higher at the α‐positions where through‐bond and direct induction coincide. The fact that the pKa of all three series of salts correlate linearly with each other points to the common nature of these inductive electron displacements.
Isolation and Structure of a New Antibiotic Related to Rubiflavin A
Authors: Nadig Heinz , Séquin Urs , Bunge Richard H. , Hurley Timothy R. , Murphey David B. , French James C.
Published: December 2004

A novel antibiotic, PD 121,222, was isolated from a complex of pluramycin‐like compounds containing mostly kidamycin and neopluramycin. Spectral analyses showed that this compound is the 14,16‐dihydroxy analog of rubiflavin A.
Preparative Asymmetric Reduction of 3‐Ketobutyrate and ‐valerate by Suspended Cells of Thermophilic Bacteria (Thermoanaerobium brockii) in Ordinary Laboratory Equipment
Authors: Seebach Dieter , Giovannini Fabio , Lamatsch Bernd
Published: December 2004

The thermophilic and anaerobic bacteria specified in the title are isolated on a 0.8 kg scale by tangential flow filtration and centrifugation from a 300‐1 bioreactor. The microorganisms are stored in a freezer (−20°) and used, analogously to baker's yeast, for asymmetric reductions. Thus, ethyl 3‐ketovalerate (4.3) g/1 (H2O) is converted in 40% yield to (S)‐3‐hydroxyvalerate (6), with an enantiomeric excess of 93% (24 h at 72°).
σ‐Skeletal‐Rearrangement of Heptalenes: Thermal Transformation of Heptalene‐1,2‐dicarboxylates into Heptalene‐1,3‐dicarboxylates
Authors: Bernhard Werner , Brügger Paul , Daly John J. , Englert Gerhard , Schönholzer Peter , Hansen Hans‐Jürgen
Published: December 2004

It is shown that dimethyl heptalene‐1,2‐dicarboxylates undergo rearrangements at temperatures > 200° to yield the corresponding 1,3‐dicarboxylates, which are isolated as the more stable 3,5‐dicarboxylates. 2H‐ and 13C‐labelling experiments with dimethyl 7‐isopropyl‐5,10‐dimethylheptalene‐1,2‐dicarboxylate (1) which is rearranged into dimethyl 9‐isopropyl‐1,6‐dimethylheptalene‐3,5‐dicarboxylates. (2) indicate that the reaction occurs by interchange of C(2) and C(3) in the heptalene skeleton of 1. Thus, the transformation of 1 into 2 represents the first thermal σ‐skeletal rearrangement of heptalenes. The structures of 1 and 2 are discussed in terms of an X‐ray analysis and the spectral data.
Thermal Reactions of Epoxyenones and Epoxydienes in the Ionone Series
Authors: O'Sullivan Anthony , Bischofberger Norbert , Frei Bruno , Jeger Oskar
Published: December 2004

On flash vaccum thermolysis at temperatures between 390 and 585°, the epoxyenones 1–9 and the epoxydienes 10–12 undergo various types of reactions involving CC and/or CO bond cleavage in the oxirane ring. Thus, the compounds 1, 4–9, 11, and 12 were transformed to the divinyl ethers 13, 20, 21, 24, 25, 29, and 38 by a reversible [1,5] homosigmatropic H‐shift. On thermolysis of the epoxides 1–12, several products formed via carbonyl‐ylide intermediates were also isolated. The extent of the formation of ylide products is clearly related to the conjugating ability of the functional groups neighboring the oxirane. Thus, the epoxides 3, 5, and 7–10, bearing a C(3)C(4) bond, a 5‐oxo function, a 3,4‐epoxy or a 3,4‐methano group, preferentially underwent reactions via a carbonyl‐ylide intermediate. As a further reaction pathway, the epoxides 1–12 undergo cleavage of the C–O bonds of the oxirane, which, however, is presumably an acid‐catalyzed rather than a thermal reaction.
N,O‐Acetals from Pivalaldehyde and Amino Acids for the α‐Alkylation with Self‐Reproduction of the Center of Chirality. Enolates of 3‐Benzoyl‐2‐(tert‐butyl)‐1,3‐oxazolidin‐5‐ones
Authors: Seebach Dieter , Fadel Antoine
Published: December 2004

The sodium salts of (S)‐alanine, (S)‐phenylalanine, (S)‐valine, and (S)‐methionine are condensed with pivalaldehyde to imines 5. Cyclization by treatment with benzoyl chloride in cold CH2Cl2 gives mainly (4:1 to > 99:1) the (2S,4S)‐4‐alkyl‐3‐benzoyl‐2‐(tert‐butyl)‐1,3‐oxazolidin‐5‐ones (6; cis‐configuration) in high yields (85–95%). The oxazolidinones 6 and 7 are deprotonated with lithium diethylamide (LDEA) in tetrahydrofuran (THF) and alkylated (Mel, benzyl bromide) or hydroxyalkylated (benzaldehyde) to 4,4‐disubstituted oxazolidinones 9 and 10, respectively, with high diastereoselectivity (9:1 to 50:1; relative topicity ul). Hydrolysis of three of the oxazolidinones to amino acids of known configuration and optical purity indicates that little if any racemization occurs in the process.
The Phloroglucinols of Dryopteris aitoniana PICHI SERM. (Dryopteridaceae, Pteridophyta)
Authors: v. Euw Josef , Reichstein Tadeus , Widén Carl‐Johan
Published: December 2004

The phenolic compounds of the fern Dryopteris aitoniana were analyzed by improved methods avoiding alcaline reagents and contact with unbuffered SiO2, which can cause deterioration. We confirmed the presence of five of the formerly (1971) reported six compounds, while the sixth, formerly incorrectly assumed to be aspidin (based on a spot in TLC), has now been isolated as cristals (TR‐1579). It has the empirical formula C27H52O2, but its structure is still unknown. Five other compounds were isolated in pure form, tetra‐albaspidin BBBB (25‐BBBB) a known but rare phloroglucinol, and four new compounds: penta‐albaspidin BBBBB (37‐BBBBB), hexa‐albaspidin BBBBBB (38‐BBBBBB), tetraflavaspidic acid BBBB (26‐BBBB) and hexaflavaspidic acid BBBBBB (39‐BBBBBB). The structures were established by degradation NMR and partly by field‐desorption and fast‐atom‐bombardment (FAB) mass spectra. The oligoflavaspidic acids are very unstable compounds, deteriorating during isolation procedures using the older ‘standard method’.
Die Sattelkonformation der hydroporphinoiden Nickel(II)‐Komplexe: Struktur, Ursprung und stereochemische Konsequenzen
Authors: Kratky Christoph , Waditschatka Rudolf , Angst Christof , Johansen Jon E. , Plaquevent Jean C. , Schreiber Jakob , Eschenmoser Albert
Published: December 2004

The Saddle Conformation of Hydroporphinoid Nickel(II) Complexes: Structure, Origin, and Stereochemical Consequences

Thirteen crystal structures document the general phenomenon of coordination‐hole contraction in hexahydro‐ and tetrahydroporphinoid ligands of complexes with small metal ions such as low‐spin Ni(II). The contraction is characterized by a deformation of the ligand system towards a saddle‐shaped, ruffled conformation of approximate S4 symmetry. The central metal ion is coplanar with the four coordinating N‐centers whereas the four C(meso)‐atoms are situated alternately above and below this coordination plane. Increasing steepness of the saddle (parameter dm) is associated with decreasing metal‐N distances. For metal pyrrocorphinates, dm increases in the order Cu(II) < (pyridine) Co(II) < Ni(II), for Ni(II) complexes it does so in the order porphyrin < chlorin < bacteriochlorin < isobacteriochlorin < pyrrocorphin. In the saddle conformation of hydroporphinoid Ni(II) complexes, the hydropyrrole rings assume half‐chair conformations whereby the individual half‐chairs are conformationally constrained in such a way that the inclination of their peripheral single bond parallels the inclination of the ligand saddle (W‐conformation of the ensemble of 5‐membered ring half‐chairs). There are only two such conformations available for a given complex; they interrelate by saddle inversion with concomitant inversion of the ensemble of half‐chairs. The coordination‐hole contraction of hydroporphinoid ligands is expected and observed experimentally to exert control on the stereochemistry and reactivity of the ligand periphery as well as on the axial electrophilicity of the central metal ion. Tetracoordinate nickel(II) pyrrocorphinates are found to favor the tctct configuration of substituents at the ligand periphery, nickel(II) isobacteriochlorinates the tct configuration, whereas nickel(II) bacteriochlorinates are expected to favor the ttt configuration. Relative rates and regioselectivities of autoxidation of nickel(II) pyrrocorphinates to corresponding bacterio‐and isobacteriochlorinates depend on the configuration and conformation of the ligand periphery. The residual axial electrophilicity of the metal ion in tetracoordinate Ni(II) complexes of the octaethyl series appears to increase in the order chlorin < isobacteriochlorin ≲ bacteriochlorin < pyrrocorphin. All hydroporphinoid metal complexes used in the X‐ray structure studies were prepared as part of exploring the porphyrinogen → pyrrocorphin tautomerization, a novel structural transformation of porphyrinogens.
Synthese neuer Nonafulvene
Authors: Sabbioni Gabriele , Otter Albin , Millar Ross W. , Neuenschwander Markus
Published: December 2004

Synthesis of New Nonafulvenes

Nonafulvenes 1c and 1m–s are prepared by the following methods: (a) Elimination of AcOH from acetoxyalkyl‐cyclononatetraenes (Scheme 2; 1m); (b) alkylation of nonafulvenolates (Scheme 3; 1c, 1n); (c) elimination of alcohol from di‐ and trialkoxymethyl‐cyclononatetraenes (Scheme 5; 1o, 1p, 1q); (d) deprotonation of intermediary formed formamidiniumcyclononatetraenes (Scheme 6; 1r, 1s). Scope and limitations of these preparative sequences are discussed and compared with the corresponding pentafulvene syntheses.
Reaktionskinetik einer Monomolekularen Oberflächenbelegung von Germanium mit 4‐(Trichlorsilylmethyl)benzonitril mit Hilfe von FTIR‐Experimenten
Authors: Calzaferri Gion , Gori Marcel
Published: December 2004

Kinetics of Monomolecular Surface Modification of 4‐(Trichlorosilylmethyl)benzonitrile on Germanium by Means of FTIR Experiments

A Fourier transform‐attenuated total internal reflection‐infrared spectroscopy (FT‐ATR‐IR) technique is described, which allows to observe the kinetics of monomolecular surface modification on materials which are feasible to total internal reflection experiments in an appropriate wavelength region. First results are reported for the reaction of 4‐(trichlorosilymethyl)benzonitrile on germanium. The reaction is slower than expected and is only completed after approximately 4 h.
Plantes de Nouvelle‐Calédonie. 94e Communication. Alcaloïdes monoterpéniques de Scaevola racemigera DÄNIKER
Authors: Skaltsounis Alexios‐Léandros , Michel Sylvie , Tillequin François , Koch Michel , Pusset Jacques , Chauvière Gérard
Published: December 2004

Monoterpene Alkaloids of Scaevola racemigera DÄNIKER

Nine alkaloids have been isolated from the aerial parts of Scaevola racemigera. Two of them are the known compounds cantleyine (1) and tetrahydrocantleyine (2). The seven others are novel alkaloids, strychnovoline (3), 6‐O‐nicotinoylstrychnovoline (4), 6‐O‐nicotinoyltetrahydrocantleyine (5), 6‐O‐(5‐vinylnicotinoyl)tetrahydrocantleyine (6), racemigerine (7), 6,7‐epoxyracemigerine (8), and scaevoline (9). The structures of the new compounds have been elucidated by their spectral data and confirmed by chemical correlations. Moreover, the absolute configuration of 2, which had not been previously determined, has been elucidated.
Das Carotinoidspektrum der Antheren und Petalen von Lilium tigrinum cv. ‘Red Night’
Authors: Märki‐Fischer Edith , Eugster Conrad Hans
Published: December 2004

Carotenoids from Anthers and Petals of Lilium tigrinum cv. ‘Red Night’

Amongst the 29 carotenoids separated and characterized by modern methods the following are worth mentioning: (9′Z)‐, (9Z)‐, (13′Z)‐ und (13Z)‐capsanthins (20–23), the novel 6‐epikarpoxanthin (= (3S,5R,6S,3′R)‐5,6‐dihydro‐β,β‐carotene‐3,5,6,3′‐tetrol; 25), karpoxanthin (= (3S,5R,6R,3′R)‐5,6‐dihydro‐β,β‐carotene‐3,5,6,3′‐tetrol; 28), and lilixanthin (= (3S,4S,3′S,5′R)‐3,4,3′‐trihydroxy‐β,κ‐carotene‐6′‐one; 26). The main carotenoids from the petals, in comparison with those of the anthers, represent a more advanced metabolic state.
Acid‐Catalyzed Cleavage of 1,4‐Dimethyl‐1,4‐dihydronaphthalene 1,4‐Endoperoxide. Reactivity of the Resulting Hydroperoxy Carbocation with Nucleophiles
Authors: Jefford Charles W. , Rossier Jean‐Claude , Kohmoto Shigeo , Boukouvalas John
Published: December 2004

In the presence of acids, 1,4‐dimethyl‐1,4‐dihydronaphthalene 1,4‐endoperoxide readily reacts with nucleophiles to produce methyl‐ and ring‐substituted naphthalenes in high yields. The regioselectivity observed depends on the nucleophile. The key intermediate is shown to be the corresponding hydroperoxy carbocation which could be intercepted in certain cases prior to aromatization. The hydroperoxide also undergoes Hock‐type cleavage and dimerization giving 2,3‐dihydro‐1‐benzoxepins, 4‐methyl‐1‐naphthol, and a 1,2,5,6‐tetraoxocane as by‐products.
Zur Anionenselektivität von Distannylderivaten in Membranen
Authors: Wuthier Urs , Pham Hūng Viêt , Pretsch Ernö , Ammann Daniel , Beck Albert K. , Seebach Dieter , Simon Wilhelm
Published: December 2004

Anion‐Selectivity of Distannyl Derivatives in Membranes

A series of distannyl derivatives (2,2‐bis(trimethylstannyl)‐1,3‐dithiane, 2,2‐bis(tributylstannyl)‐1,3‐dithiane, hexamethyldistannane, hexabutyldistannane, hexaphenyldistannane, bis(triphenylstannyl)sulfide, o‐bis(trimethylstannyl)benzene) has been studied in view of their applicability as anion‐selective ionophores in solvent polymeric membranes. None of these compounds induces significant changes in the anion‐selectivity pattern as compared with the membranes containing no organotin compound. Representatives with tributylstannyl groups, however, undergo chemical reactions leading to highly active anion ionophores of the type Bu3SnX, several of which (e.g. Bu3SnCl and Bu3SnOH) may be present in equilibrium in the membrane phase depending on the measuring conditions.
Synthèse des (R)‐ et (S)‐O‐isopropylidène‐1,2‐glycérols. Détermination de la pureté optique
Authors: Hirth Georges , Walther Willy
Published: December 2004

Synthesis of the (R)‐ and (S)‐Glycerol Acetonides. Determination of the Optical Purity

The optical purity of (R)‐glycerol acetonide (1) and (S)‐glycerol acetonide (1′) has been determined with great accuracy by gas chromatography after derivatization. The optical purity of (S)‐glycerol actonide prepared from D‐mannitol was > 99.4% while for (R)‐glycerol acetonide obtained from L‐serine it was 95%.
Aniono‐pentaaminecobalt(III) complexes with polyamine ligands. Part 23. A chloropentaamine by‐product from the preparation of the trans‐CoCl2(en) cation
Authors: House Donald A.
Published: December 2004

The isolation and characterisation of [CoCl(en)(L)]ZnCl4, L = NH2CH2CHNCH2CH2NH2 (1,4,7‐triazahept‐3‐ene), as a by‐product (∼ 8% yield) from the H2O2 synthesis of trans‐CoCl2(en), is described.
Photo‐Emde Degradation of 1,2,3,4‐Tetrahydroquinolinium Salts
Authors: Partali Vassilia , Jolidon Synèse , Hansen Hans‐Jürgen
Published: December 2004

It is shown that 1,1‐dimethyl‐1,2,3,4‐tetrahydroquinolinium ions undergo, under direct irradiation through quartz in CH3OH and independent of the nature of the counterion (I−, BF), a reductive cleavage of the N(1)–C(8a) bond (photo‐Emde degradation). The corresponding N,N‐dimethyl‐3‐phenylpropylamines are formed in high yields and without contamination by Hofmann degradation products of the tetrahydroquinolinium salts. Me groups at C(2) as well as substituents at C(6) (CH3, Cl, CH3O) favour the photo‐Emde degradation. The aromatic Cl‐substituent is reductively split off in the course of the photoreaction.
Cycloaddition of 2H‐Pyran‐2‐thiones with Nitroso Derivatives. An Unexpected Cycloaddition‐Rearrangement Reaction
Authors: Defoin Albert , Augelmann Gérard , Fritz Hans , Geffroy Guillaume , Schmidlin Christian , Streith Jacques
Published: December 2004

Reaction of pyran‐2‐thiones 4 with nitroso derivatives led surprisingly to type‐8 (19) adducts which proved to be isomeric with the initially expected primary Diels‐Alder cycloadducts 5. Methyl 2‐thioxo‐2H‐pyran‐5‐carboxylate (4f), when reacted with nitrosobenzene at ‐10°, led quantitatively to the thieto‐oxazine intermediate 13, which turned out to be the cornerstone of the complex cycloaddition‐rearrangement 5 → 8 reaction pathway (Scheme 3). Differential scanning calorimetry, as performed for the 18a → 19a conversion, permitted to demonstrate that this multistep rearrangement is overall a higly exothermal process, the final product 19 representing an energy‐sink along this reaction pathway.
Significance of the Geminal Dimethyl Group in the Odor Principle of Ambrox®
Authors: Ohloff Günther , Giersch Wolfgang , Pickenhagen Wilhelm , Furrer Anton , Frei Beatrice
Published: December 2004

The diastereoisomeric 18‐nor‐ and 19‐norambrox ((6α)‐ and (6β)‐dodecahydro‐3a,6,9a‐trimethylnaphtho[2,1‐b]furans resp.) as well as the corresponding 18,19‐dinor‐derivatives (dodecahydro‐3a,9a‐dimethylnaphtho[2,1‐b]furans) have been synthesized and subjected to sensory evaluation. Threshold data and odor determination give an enlarged insight into the structure‐activity relationship (SAR) in ambrox‐type ambergris fragrances. As a general conclusion, the accumulation of axial CH3 groups in the tricyclic ethers 1–12 leads to the strongest receptor affinity.
Synthese von 12‐Cyano‐15‐hexadecanolid durch Ringerweiterung von 1‐(3′‐Hydroxybutyl)‐2‐oxocyclododecan‐1‐carbonitril
Authors: Milenkov Branimir , Süsse Manfred , Hesse Manfred
Published: December 2004

Synthesis of 12‐Cyano‐15‐hexadecanolide by Ring Enlargement of 1‐(3′‐Hydroxybutyl)‐2‐oxocyclododecane‐1‐carbonitrile

In the presence of Bu4NF, 2‐oxocyclododecane‐1‐carbonitrile (1) reacted with acrylaldehyde to form the corresponding aldehyde 2 which was methylated, e.g. with CH3 Ti[OCH(CH3)2]3. The resulting 1‐(3′‐hydroxybutyl)‐2‐oxocyclododecane‐1‐carbonitrile (5) was converted to 12‐cyano‐15‐hexadecanolide (6) in nearly quantitative yield under the influence of Bu4NF.