bluuebunny/crossref_metadata_2025 huggingface dataset:
Conformation and Optical Activity of all‐trans, mono‐cis, and di‐cis Carotenoids: Temperature Dependent Circular Dichroism
Authors: Noack Klaus , Thomson Andrew J.
Published: December 2004

The CD. spectra of carotenoids with an asymmetric centre at C(3) have the following unusual features: (1) All‐trans and di‐cis compounds with two end‐rings, at least one of which possesses an asymmetric C‐atom, have very similar CD. spectra, whereas the corresponding mono‐cis compounds give mirror‐image CD. spectra; (2) In carotenoids or apocarotenoids with only one end‐ring all‐trans and mono‐cis compounds have the same CD. spectra; (3) The CD. spectra of such carotenoids are strongly temperature dependent either increasing in magnitude or completely changing in sign upon cooling.

These properties have been rationalized with the aid of a model with takes the total chromophore of the carotenoid as being intrinsically chiral with symmetry C2. It seems that the chirality arises not only from the presence of the hydroxyl group of an asymmetric carbon atom, C(3), which occupies an equatorial position thereby locking the conformation of the end‐ring, but also from the steric hindrance across the formal single bond C(6), C(7), linking the end‐ring to the chain and thus creating a chiral π‐system. (The twist about the C(6), C(7)‐bond acquires a handedness because of the predominance of one conformational form of the end‐ring. In this way, the double bonds of the end‐ring become twisted out of the plane of the chain with one hand predominating. Thus the whole conjugated system becomes chiral). The reversal of sign between the trans (and di‐cis) and mono‐cis compounds is due to a tilt of the 2‐fold symmetry axis and thereby a change of chirality. The temperature dependence stems from the varying population of forms of different twist of the end‐group relative to the chain.

Compounds with 7, 8‐triple bonds also show distinct CD. spectra and a sign change between all‐trans and mono‐cis isomers in addition to temperature dependence. The latter property demonstrates that some steric hindrance between the end‐ring and the main chain is present in these compounds.

Some suggestions for the origins of the sign patterns and band intensities of the CD. and absorption spectra are included.
Carotinoid‐Glycosylester. 3. Mitteilung. Die synthese von crocetin‐di‐(β‐D‐glucosyl)‐ester. Eine neue methode zur selektiven veresterung von ungeschützter β‐D‐glucose
Authors: Pfander Hanspeter , Wittwer Fritz
Published: December 2004

Carotenoid Glycosyl Esters. The Synthesis of Crocetin‐di‐(β‐D‐glucosyl) Ester. A New Method for the Selective Esterification of Unprotected β‐D‐Glucose

The naturally occurring crocetin‐di‐(β‐D‐glucosyl) ester is easily synthesized by the reaction of crocetin‐di‐imidazolide or crocetin‐di‐(1,2,4‐triazolide) and unprotected β‐D‐glucose in pyridine in presence of a base (Scheme 4). Under the described experimental conditions the esterification takes place exclusively at the anomeric C‐atom and furthermore produces only the β‐anomer. It is the first time that an unprotected carbohydrate has been used for the selective synthesis of glucosyl esters at the anomeric C‐atom. This represents the major advantage of this new method.
Photo‐CIDNP. Investigation of β,γ‐Unsaturated Ketones: Evidence for Temperature‐dependent S1vs. T2 Reactivities of Cyclopent‐2‐enyl Methyl Ketones
Authors: Henne Andreas , Siew Nancy P. Y. , Schaffner Kurt
Published: December 2004

On ultraviolet irradiation of the cyclopent‐2‐enyl methyl ketones 1a–c at −54° ⩽ t ⩽ 139°, photo‐CIDNP. effects of the starting ketones, the 1,3‐acetyl shifted isomers (2), and radical disproportionation and combination products (4–7) were observed. These effects show a unique dependence of the polarization phase on temperature which is a novel feature in photo‐CIDNP. studies. The results of the investigation, which also included experiments using triplet quenchers, triplet sensitizers and radical scavengers, are rationalized in terms of Schemes 2 and 3.

α‐Cleavage is a major excited‐state reaction of 1a–c on direct irradiation. Temperature‐activated α‐cleavage (k(t)) to the radical pair R · · R′1 and intersystem crossing (kisc) to the T2 state are among the competing S1 deactivation processes. The T2 state in turn cleaves (k) to R · · R′3 A ‘low‐temperature range’ with kisc ≫ k(t) and a ‘high‐temperature range’ with k(t) ≫ kisc exhibiting preferential reactivity from the T2 and S1 states, respectively, can be defined for all three β,γ‐unsaturated ketones 1a–c.
High Syn Selectivity of a SE′ Reaction: Acylation of an Optically Active 1,1‐Disilyl‐2‐alkene. Preliminary communication
Authors: Wetter Hansjürg , Scherer Paul , Schweizer W. Bernd
Published: December 2004

The disilane/disilylmethane rearrangement of an optically active disilanyl sulfide 9B was used to prepare an optically active disilylalkene 10 whose absolute configuration was established by X‐ray analysis of the bromo derivative 13 (P21, a = 7.847 (3) Å, b = 9.487 (3) Å, c = 20.010 (8) Å, β = 82.28° (3), Z = 2). Acylation of 10 furnished an optically active ketone 14, which was degraded to 16, a compound of known absolute configuration. The enantiomeric excess of 10 was determined by alkylation with an optically active lithium compound and that of 14 by an optically active NMR.‐shift reagent. The SE′ reaction 10 → 14 was thus shown to proceed with 94% (97% syn/3% anti) stereoselectivity.
1‐Substituted 1,3‐Dihydroisothianaphthen‐2,2‐dioxides: Preparation and Use as ortho‐Quinodimethane Precursors in Intramolecular Cycloadditions. Preliminary communication
Authors: Oppolzer Wofgang , Roberts David A. , Bird T. Geoffrey C.
Published: December 2004

1,3‐Dihydroisothianaphthen‐2,2‐dioxide (1) was readily converted to the 1‐substituted sulfones 3 by deprotonation and subsequent electrophilic attack (Scheme 3 and Table). The appropriate 1‐alkenyl‐ and 1‐alkenoyl‐sulfones 3 on heating at 213° to 240° underwent SO2‐extrusion to give, via the non‐isolated (E)‐quinodimethanes II (Scheme 1), polycyclic products such as 4, 6 and 7 in good yields (Schemes 4 and 5). On the other hand, thermolysis of the 1‐alkenoyl‐1‐thioether sulfones 9 furnished mainly the isochromenes 10 (Scheme 6).
Synthetische Verwendung von Epoxynitronen. III. Der anomere Effekt als bestimmender Faktor für die Konformation der 3‐Cyano‐perhydro‐1,2‐benzoxazine
Authors: Riediker Martin , Graf Walter
Published: December 2004

The anomeric effect as a conformation determining factor for 3‐cyano‐perhydro‐1,2‐benzoxazines

An unusual population of conformer II is found by 1H‐NMR. spectroscopy in the conformation equilibrium I⇄ II of 1b (Fig. 3) in which the non‐bonding nitrogen electronpair is anti‐periplanar to the CCN bond. This finding is interpreted in terms of a generalized anomeric effect operating in the α‐cyano‐hydroxylamin‐ether structural unit.
Ionophore extrem hoher Lipophilie als selektive Komponenten für Flüssigmembranelektroden
Authors: Oesch Urs , Ammann Daniel , Pretsch Ernö , Simon Wilhelm
Published: December 2004

Selective ionophores of extreme lipophilicity for liquid membrane electrodes

Lipophilic ionophores of the type diether diamides have been prepared. Their lipophilicity is up to 7 orders of magnitude higher than the one of the most lipophilic ion carriers used as selective components in liquid membrane electrodes reported so far. For such ion carriers of extremely high lipophilicity kinetic limitations of the carrier induced ion transfer between aqueous and membrane phase usually dominate and heavily disturb the electromotive behavior of the membrane electrode. These limitations are absent only in those cases where most of the lipophilic segments of the carrier may remain in the membrane phase while the segments with the coordination sites are exposed to the aqueous phase during the transfer process.
195Pt‐NMR. Spectroscopy. The direct measurement of the values 1J (195Pt, 14N) and chemical shift data for the complexes trans‐[PtCl2(C2H4) (substituted pyridine)]
Authors: Motschi Herbert , Sze Siu N. , Pregosin Paul S.
Published: December 2004

The values nJ (195Pt, 14N) are shown to be measurable directly from the 195Pt spectrum for a variety of complexes containing nitrogen ligands. The sample temperature can play an important role in determining the width of the 195Pt signal. 195Pt chemical shifts for the complexes trans‐[PtCl2(C2H4) (substituted pyridine)] have been measured. Methyl substitution at the 2‐ and 6‐positions produces a relatively large downfield shift.
Transition Metal Complexes with Bidentate Ligands Spanning trans‐Positions. VII. The preparation of the five‐coordinate complexes [M(CO)3(1)] (M = Fe, Ru; (1) = 2,11‐bis(diphenylphosphinomethyl)benzo[c]phenanthrene)
Authors: Holderegger Rolf , Venanzi Luigi M.
Published: December 2004

The five‐coordinate mononuclear complexes [M(CO)3(1)] (M = Fe, Ru; (1) = 2,11‐bis(diphenylphosphinomethyl)benzo[c]phenanthrene) have been prepared and assigned trigonal bipyramidal structures with apical phosphorus atoms from IR. and NMR. data.
Synthesis of (R)‐ and (S)‐p‐Mentha‐1,8‐dien‐4‐ols from (R)‐Limonene
Authors: Delay François , Ohloff Günther
Published: December 2004

Synthesis of both enantiomers of p‐mentha‐1,8‐dien‐4‐ol (1) from commercially available (+)‐(R)‐limonene (2) is described.
Anwendung der «Zip»‐Reaktion zur Synthese eines 53gliedrigen Polyaminolactams. 8. Mitteilung über Umamidirungsreaktionen
Authors: Kramer Urs , Guggisberg Armin , Hesse Manfred
Published: December 2004

Use of the ‘Zip’ reaction for the synthesis of a 53‐membered polyminolactam

The synthesis of N‐(39‐amino‐4, 8, 12, 16, 20, 24, 28, 32, 36‐nonaaza‐nonatriacontyl)‐12‐dodecanlactam (1)

In ‘5’ wurden die Verbindungen 1 als 1‐(39‐Amino‐4,8,12,16,20,24,28,32,36‐nonaazanonatriacontyl)‐1‐azacyclotridecan‐2‐on, 4 als 7‐Chlor‐1‐phthalimido‐4‐tosyl‐4‐azaheptan, 5 als 7‐Jod‐1‐phthalimido‐4‐tosyl‐4‐azaheptan und 20 als 1,5,9,13,17,21,25,29,33,37,41‐Undecaazatripentacontan‐42‐on bezeichnet.

has been described. The formation of synthon
2
, used for the chain extension of the known
12
[6] shown in
Scheme 2
, is demonstrated in
Scheme 1
. In presence of base (KAPA‐reagent),
1
undergoes the so called ‘Zip’‐reaction resulting in a ring‐expansion by 40 members which leads to
20
.
The Reaction of Cyclopropyl Ketones with Acetyl Methanesulfonate. An efficient ring opening under neutral conditions with regiospecific enol acetate formation and stereo‐controlled nucleophilic addition. Preliminary communication
Authors: Demuth Martin , Raghavan Palaykotai R.
Published: December 2004

Cyclopropyl ketones are readily cleaved under neutral conditions at room temperature by the combined action of acetyl methanesulfonate and nucleophiles such as Br−, I−, and MsO−. The high‐yield reaction involves regiospecific enol acetate formation with a stereoselectivity of nucleophile addition which is compatible with an SN2‐type opening of the cyclopropyl ring.
Strukturen von 13 Diterpenen (Coleonen) aus Blattdrüsen von Solenostemon sylvaticus und Coleus garckeanus (Labiatae)
Authors: Miyase Toshio , Yoshizaki Fumihiko , Kabengele N'Tanda , Rüedi Peter , Eugster Conrad Hans
Published: December 2004

Leaf‐gland pigments from labiatae: structures of 13 diterpenoids (coleons) from Solenostemon sylvaticus (GÜRKE) T.T. AYE and Coleus garckeanus VATKE

The above mentioned East‐African labiatae have been investigated for their leaf‐gland pigments. The two plants contain very similar abietanoic diterpenoids. Besides the already known coleons O (5a) and W (1a), 11 novel compounds have been isolated and their structures established:

Diosphenol: 16(or 17)‐O‐acetyl‐coleon W (1b).

Diketones: Coleon X (16 or 17)‐acetoxy‐11, 12, 14, 17 (or 16)‐tetrahydroxy‐abieta‐8, 11, 13‐triene‐6,7‐dione (2a); 16 (or 17)‐O‐acetyl‐coleon X (2b).

Spiro‐coleons: 6‐O‐acetyl‐19‐acetyloxy‐coleon Q (3b); 12‐O‐desacetyl‐7‐O‐acetyl‐19‐acetyloxy‐coleon Q (3c); 12‐O‐desacetyl‐7‐O‐acetyl‐19‐acetyloxy‐coleon P (3e); 12‐O‐desacetyl‐7‐O‐acetyl‐3β, 19‐diacetyloxy‐coleon Q (4b); 19‐acetyloxy‐coleon O (5b); 12‐O‐desacetyl‐6‐O‐acetyl‐17‐acetyloxy‐coleon P (7); 7‐desoxy‐12‐O‐desacetyl‐3‐acetyloxy‐coleon N (6b); coleon Z (8).

Compound 7 contains a spiro cycloprope unit, substituted by one carbonyl and two carbinol functions. Compound 8 (Coleon Z) contains a unique cis‐butadiene unit formed from C(3)–C(4)–C(18)–C(19).
Totalsynthese von natürlichem α‐Tocopherol. 4. Mitteilung. Aufbau des Chromanringsystems aus Trimethylhydrochinon und einem optisch aktiven C4‐ bzw. C5‐Synthon
Authors: Barner Richard , Schmid Max
Published: December 2004

Total Synthesis of Natural α‐Tocopherol

Two independent syntheses of (S)‐6‐hydroxy‐2,5,7,8‐tetramethylchroman‐2‐yl‐methanol (8b), (Scheme 6 resp. 9) as optically active chroman moiety for the preparation of natural vitamin E via (S)‐6‐acetoxy‐2,5,7,8‐tetramethylchroman‐2‐carboaldehyde (2a) (Scheme 1) and a corresponding side chain are described. Both reaction sequences use trimethyl‐hydroquinone as starting material; one approach employs an optically active C4 unit (10a) (Schemes 5 and 6) to introduce the required configuration at C(2), the other uses an optically active C5‐synthon (11a) (Schemes 8 and 9) to build the optically active chroman unit. The correct configuration and optical purity of the chroman synthesized is established by correlation with optically pure material of known configuration from which natural vitamin E had already been derived [2].
Carbocyclische Verbindungen aus Monosacchariden. II. Umsetzungen in der Mannosereihe
Authors: Bernet Bruno , Vasella Andrea
Published: December 2004

Carbocyclic compounds from monosaccharides. II. Transformations in the mannose series

Upon treatment with Zn in refluxing aqeous ethanol or butanol, the anomeric mannopyranosides 11 and 14 yielded the aldehyde 15 which was subjected (via its N‐methyl‐nitrone) to an intramolecular nitrone‐olefine cycloaddition leading diastereoselectively to 18 in a yield of 64% from 14. Minor products of this reaction sequence were the compounds 19, 20 and 21. Similarily, the easily accessible unsaturated furanose 26, upon treatment with N‐methyl‐hydroxylamine gave the isoxazolidines 27 (84%) and 28 (3%), thus showing that a free 4‐hydroxy group is not detrimental to this intramolecular nitrone‐olefin cycloaddition. The configuration of 18, 27 and 28 (resp. 29) were determined by spectroscopic means; that of 27 was further proven by transformation into the compound 31, of which an X‐ray analysis was performed.
Defense Allomones of the Nudibranch Phyllidia varicosa Lamarck 1801
Authors: Hagadone Mark R. , Burreson B. Jay , Scheuer Paul J. , Finer Janet S. , Clardy Jon
Published: December 2004

The defensive secretion of the nudibranch Phyllidia varicosa consists of two isocyanosesquiterpenes: the previously described 9‐isocyanopupukeanane (1), and its 2‐isomer (4), for which we report the structure and properties. The mixture originates with a sponge, Hymeniacidon sp., where it is produced in varying proportions. CD. measurements and X‐ray diffraction data establish the absolute configuration of the two metabolites.
Bestrahlung von 4‐allylierten 2,6‐Dimethylanilinen in Methanol
Authors: Bader Heinz , Hansen Hans‐JüRgen
Published: December 2004

Irradiation of 4‐Allylated 2,6‐Dimethylanilines in Methanol

4‐Allyl‐, 4‐(1′‐methylallyl)‐, 4‐(2′‐butenyl)‐, and 4‐(1′,1′‐dimethylallyl)‐2,6‐dimethylaniline (14–17; cf. Scheme 3) were obtained by the acid catalysed, thermal rearrangement of the corresponding N‐allylated anilines in good yields. Aniline 14, when irradiated with a high pressure mercury lamp through quartz in methanol, yielded as main product 4‐(2′‐methoxypropyl)‐2,6‐dimethylaniline (22; cf. Scheme 4) and, in addition, 2,6‐dimethyl‐4‐propylaniline (18) and 4‐cyclopropyl‐2,6‐dimethylaniline (23). The analogous products, namely erythro‐ and threo‐4‐(2′‐methoxy‐1′‐methylpropyl)‐2,6‐dimethylaniline (erythro‐ and threo‐24), 2,6‐dimethyl‐4‐(1′‐methylpropyl)aniline (19), trans‐ and cis‐2,6‐dimethyl‐4‐(2′‐methylcyclopropyl)aniline (trans‐ and cis‐25), as well as small amounts of 4‐ethyl‐2,6‐dimethylaniline (26), were formed by irradiation of 15 in methanol (cf. Scheme 5). When this photoreaction was carried out in O‐deuteriomethanol, erythro‐ and threo‐24 showed an up‐take of one deuterium atom in the side chain. The mass spectra of erythro‐ and threo‐24 revealed that in 50% of the molecules the deuterium was located at the methyl group at C(1′) and in the other 50% at the methyl group at C(2′) (cf. Scheme 6). This is a good indication that the methanol addition products arise from methanolysis of intermediate spiro[2.5]octa‐4,7‐dien‐6‐imines (cf. Scheme 7). This assumption is further supported by the photoreaction of 17 in methanol (cf. Scheme 8) which led to the formation of 4‐(2′‐methoxy‐1′,2′‐dimethylpropyl)‐2,6‐dimethylaniline (28) as main product. The occurrence of a rearranged side chain in 28 can again be explained by the intervention of a spirodienimine 31 (cf. Scheme 9). In comparison with 14, 15 and 17, the 2′‐butenylaniline 16 reacted only sluggishly on irradiation in methanol (cf. Scheme 10). It is suggested that all photoproducts ‐ except for the cyclopropyl derivatives which are formed presumably via a triplet di‐π‐methane rearrangement ‐ arise from an intramolecular singlet electron‐donor‐acceptor complex between the aniline and ethylene chromophor of the side chain. Protonation of this complex at C(3′) or C(2′) will lead to diradicals (e.g. 33 and 34, respectively, in Scheme 11). The diradicals of type 33 undergo ring closure to the corresponding spirodienimine intermediates (e.g. 31) whereas the diradicals of type 34 take up two hydrogen atoms to yield the photo‐hydrogenated compounds (e.g. 21) or undergo to a minor extent fragmentation to side chain degraded products (e.g. 30; see also footnote 7).–Irradiation of 4‐ally‐2,6‐dimethylaniline (14) in benzene or cyclohexane yielded the corresponding azo compound 38 (cf. Scheme 12), whereas its N,N‐dimethyl derivative 41 was transformed into the cyclopropyl derivative 42. The allyl moiety in 14 is not necessary for the formation of azo compounds since 2,4,6‐trimethylaniline (39) exhibited the same type of photoreaction in benzene solution.
Macrocyclic Ring Closure of OH‐assisted Prins Reaction. A new and efficient synthesis of (R,S)‐muscone
Authors: Schulte‐Elte Karl H. , Hauser Arnold , Ohloff Günther
Published: December 2004

A new strategy for the synthesis of muscone (1) using the OH‐assisted Prins reaction for macrocyclic ring closure has been developed. The monoacetal 4 of (Z,E)‐4,8‐dodecadienedial (3), easily obtainable from (Z,E,E)‐1,5,9‐cyclododecatriene (2), is treated with methallylmagnesium chloride, and the resulting C16‐precursor 5 is subjected to acid‐catalyzed cyclization in dilute (⩽1%) solutions. This results in formation of the bicyclic dihydropyran derivatives 6 which directly yield muscone (1) on heating with a noble metal catalyst saturated with hydrogen. The five‐step pathway proceeds with readily available starting materials in conventional steps and excellent overall yield (∼40%). This new principle of macrocyclic ring formation has also been used successfully for the preparation of 3‐methylcyclotridecanone (34) and should be generally applicable for other suitable ring systems.
Three New Chiral Aminoethers from Tartaric Acid for Improved Asymmetric Syntheses with Organolithium Reactions. Preliminary communication
Authors: Seebach Dieter , Crass Gerhard , Wilka Eva‐Maria , Hilvert Don , Brunner Edi
Published: December 2004

The chiral aminoethers 1–4, accessible from tartaric acid, are tested as complexing ligands in organolithium reactions. The tetramine 4 turns out to cause highest inductions [see Table 2 and Equations (1)–(4)].
Über die Stereospezifität der α‐Alkylierung von β‐Hydroxycarbonsäureestern. Vorläufige Mitteilung
Authors: Fráter György
Published: December 2004

About the Stereospecific α‐Alkylation of β‐Hydroxyesters

It was found, that dianions derived from β‐hydroxyesters with lithium diisopropylamide (LDA) at −50 to −20° were alkylated stereospecifically (Scheme 1). The stereospecificity was 95–98%, the threo‐compound (threo‐2, ‐3 and ‐4) being the main product. This was proved for threo‐2 and ‐3 by preparing the β‐lactones 7 and 8, respectively, which were pyrolyzed to trans‐1, 4‐hexadiene (9) and trans‐1‐phenyl‐2‐butene (10), respectively (Scheme 2). Moreover, the acid threo‐6 from threo‐3 was converted by dimethylformamide‐dimethylacetal to cis‐1‐phenyl‐2‐butene (11) (s. footnote 6).

The alkylation of α‐monosubstituted β‐hydroxyesters also turned out to be stereospecific. Reduction of 16 and 18 with actively fermenting yeast furnished (+)‐17 and (+)‐2. respectively (Scheme 4), which were each mixtures of the (2R, 3S)‐ and the (2S, 3S)‐isomers. Alkylation of (+)‐17 with allyl bromide yielded after chromatography (2S, 3S)‐19 and of (+)‐2 with methyl iodide (2R, 3S)‐19, the oxidation of which finally gave (S)‐(−)‐20 and (R)‐(+)‐20, respectively.
Aktivierte Chinone: regiospezifische Synthesen von substituierten Dibenzo [b, d]pyran‐6‐onen und Benzo [b]naphtho [d]pyran‐6‐onen
Authors: Müller Peter , Venakis Thomas , Eugster Conrad Hans
Published: December 2004

Activated Quinones: Regiospecific Syntheses of Substituted Dibenzo [b, d]pyran‐6‐ones and Benzo[b]naphtho [d]pyran‐6‐ones

The reaction of 2‐methoxycarbonyl‐1, 4‐benzoquinone (1) with substituted phenols leads in an acid‐catalyzed, regiospecific way to substituted dibenzo [b, d]‐pyran‐6‐ones (compounds 3 and 6). The cycloaddition of 1,3‐butadiene to the latter yields compounds 7. Tautomerisation of 7 and oxidation gives the benzo[b]‐naphtho[d]pyran‐6‐ones 8 and 10, respectively.
Oxydations et halogénations régiosélectives et réactions carbéniques de dérivés de sucres portant un groupement thioéther
Authors: Tronchet Jean M. J. , Eder Hansjörg
Published: December 2004

Regioselective Oxidations, Regioselective Halogenations and Carbene Reactions of Sugar Derivatives Bearing a Thioether Group

Regioselective stoechiometrically controlled procedures are described for the oxidation of thiosugars either at the sulfur atom (to sulfoxides or sulfones) or at a hydroxymethylene group (to ketosugars). Ruthenium tetraoxide reacted at both sites. Chloration (SO2Cl2) of β‐ketothioether sugar derivative 3 took place exclusively at C(6). Evidence is given that a chlorosulfonium intermediate C was formed when the dichloroketothiosugar derivative 6 was treated with SO2Cl2. The carbene generated from the tosylhydrazone 16 rearranged to the enoses 17–20, the migrating group coming in equal proportions from C(4) and C(6). Some stereochemical aspects of these reactions are discussed.
A Class of Trinuclear Clusters with Carbonyl Bridging
Authors: Pinhas Allan R. , Albright Thomas A. , Hofmann Peter , Hoffmann Roald
Published: December 2004

The impetus for this work was the structure of a trinuclear complex with two carbonyl groups showing incipient triple bridging ‐ Cp2Rh3(CO)4−. Its structure, barrier to rotation of one Rh(CO)2− piece vs. the rest of the molecule, and the nature of the bridging carbonyl interaction are analyzed. Isolobal analogies form an interesting connection between this complex and a bridged isomer of the recently synthesized carbene complexes, Cp2Rh2(CO)2CR2, one isomer of Cp2Rh3(CO)3, and hypothetical carbyne complexes Cp2Rh2(CO)2CH+,−. A general bonding model for Cp2Rh2(μ‐CO)2X complexes is constructed. The model, rich in geometrical detail, allows minima for the bridging carbonyl groups bending toward and away from the bonded ligand X.
Stereochemistry‐Activity Relationships in Olfaction. Odorants containing a proton donor/proton acceptor unit
Authors: Ohloff Günther , Giersch Wolfgang
Published: December 2004

A novel class of odorants is described where the odor is associated with the interaction of two functional groups, one being an H‐donor (AH function), and the other an H‐acceptor (B function). Generally, odor occurs only if the distance between the two structural elements (AH/B system) is less than 3 Å. Bifunctional derivatives of the p‐menthane and iridane series served as models for deriving this rule. The stereospecificity of odor perception was an important prerequisite for its establishment.
Drüsenfarbstoffe aus Labiaten: Ecklonochinone A und B, zwei neuartige Dibenzo‐p‐dioxin‐o‐chinone aus Plectranthus ecklonii BENTH
Authors: Uchida Masaaki , Rüedi Peter , Eugster Conrad Hans
Published: December 2004

Leaf‐gland Pigments from Labiatae: Ecklonoquinones A and B, Two Novel Dibenzo‐p‐dioxine‐o‐quinones from Plectranthus ecklonii BENTH

From the leaf‐glands of the above mentioned labiate the following compounds have been isolated and their structures established: ecklonoquinone A (1) and ecklonoquinone B (2), two novel isomeric dibenzo‐p‐dioxine‐orthoquinones; 2 (S)‐5,4′‐dihydroxy‐6,7‐dimethoxyflavanone (8); the already known flavone cirsimaritin (9) and the diterpenoid p‐quinomethane parvifloron F (10a). The spectral data of the dimeric p‐menthanes 1 and 2 are very similar, and only analysis of the 1H‐coupled 13C‐NMR.‐spectra lead to structures 1 and 2, respectively. Our tentative assignment of these structures to the individual molecules is based on a comparison of the spectral data with the synthetic compound 7.
Stoffwechselprodukte von Mikroorganismen. 190. Mitteilung. Über das 4‐Oxo‐homotyrosin, ein Abbauprodukt des Echinocandins B
Authors: Keller‐Schierlein Walter , Joos Beda
Published: December 2004

D, L‐4‐Oxo‐homotyrosine was synthesized by the acetylaminomalonic ester pathway. The optical resolution was carried out by means of the enzyme acylase I. The L‐configuration of the enzymatically produced amino acid was confirmed by degradation to L‐aspartic acid.

4‐Oxo‐homotyrosine obtained by degradation of the polypeptide antibiotic echinocandine B has D‐configuration, but his optical purity is low. A hypothetical explanation for its formation from the (2 S, 3 S, 4 S)‐3,4‐dihydroxyhomotyrosine residue of echinocandine B is proposed.
Synthesis and Configuration of the Eight Diastereoisomeric Racemates of Dactyloxene‐B. The relative configuration of dactyloxene‐B and ‐C
Authors: Maurer Bruno , Hauser Arnold , Thommen Walter , Schulte‐Elte Karl H. , Ohloff Günther
Published: December 2004

The eight possible diastereoisomeric racemates of dactyloxene‐B have been synthesized by a non‐stereoselective route and their configurations and predominant conformations determined by 360‐MHz‐1H‐NMR. and 90.5‐MHz‐13C‐NMR. spectroscopy. Natural dactyloxene‐B and ‐C are shown to have the relative configuration rel‐(2R, 5R, 9S, 10R) and rel‐(2R, 5S, 9S, 10R), respectively.
Papain Catalyzed Oligomerization of α‐Amino Acids. Synthesis and characterization of water‐insoluble oligomers of L‐methionine
Authors: Jost Rolf , Brambilla Edgardo , Monti Julio C. , Luisi Pier Luigi
Published: December 2004

Water‐insoluble oligomers were synthesized from L‐methionine ethyl ester with papain as the catalyst. L‐Oligomethionine was obtained in yields of 50% when synthesis was carried out in highly concentrated citrate buffer at pH 5.5. Yields of up to 85% were obtained when the enzymatic synthesis proceeded in distilled water at pH 6.5, the pH being strictly maintained. The insoluble polymer was converted to highly water‐soluble sulfoxide and sulfone derivatives, which consist mainly of an octamer with low amounts of heptamer or hexamer. Most of the carboxyl terminals still contained the ethyl ester group, only a minor part being present in the free acid form. The potential of the enzymatic approach for the synthesis of optically pure and monodisperse oligomers of α‐amino acids is discussed.
Transition‐Metal Complexes with Bidentate Ligands Spanning trans‐Positions. IX. Preparation and 1H‐NMR. Studies of complexes [MX2(1)] and [M′Cl(CO)(1)] (M = Pd, Pt; M′ = Rh, Ir; X = Cl, Br, I; 1 = 2, 11‐Bis‐(diphenylarsinomethyl)benzo[c]phenanthrene) and crystal and molecular structure of [PtCl2(1)]
Authors: Balimann Giovanni , Venanzi Luigi M. , Bachechi Fiorella , Zambonelli Luigi
Published: December 2004

The preparation of the bidentate ligand 2, 11‐bis(diphenylarsinomethyl)benzo‐[c]‐phenanthrene (1) is described. This ligand reacts with appropriate substrates to give mononuclear square planar complexes of type [MX2(1)] (M = Pd, Pt; X = Cl, Br, I) and [M′Cl(CO)(1)] (M′ = Rh, Ir) in which ligand 1 spans trans‐positions. This is confirmed by the crystal structure of [PtCl2(1)]. 1H‐NMR. spectra of the complexes are discussed and compared with those of model compounds trans‐[MCl2(12)2] (M = Pd, Pt) and [M'Cl(CO)(12)2] (M′ = Rh, Ir; 12 = AsBzPh2).
Radical Cation States of 2,3,5,6,7,8‐Hexamethylidenebicyclo [2.2.2]octane
Authors: Mohraz Manijeh , Jian‐qi Wang , Heilbronner Edgar , Vogel Pierre , Pilet Olivier
Published: December 2004

The photoelectron spectrum of the title compound is reported and assigned by correlation with the photoelectron spectra of related molecules.
Computation of the ESR. Coupling Constants of the [16]Annulene Radical Anion; Theoretical and Experimental Reinvestigation of the Excited States of [16]Annulene and its Mono‐ and Dinegative Ions
Authors: Baumann Harold , Oth Jean F. M.
Published: December 2004

The problem of assigning the two small ESR. coupling constants of the [16]annulene radical anion to the two sets of four equivalent outer and inner ring protons is treated by three different semiempirical MO methods. All three methods indicate that the smaller coupling constant (0.743 Gauss) should be assigned to the inner protons, and the larger one (0.963 Gauss) to the outer ones. The electronic spectra of [16]annulene, its radical anion, and its dianion have been remeasured. Especially interesting was the detection of a symmetry‐forbidden band of the radical anion at 1473 nm (6789 cm−1, logε 2.57). The spectra are discussed in terms of different MO models.
Photoreaktionen des 3‐(2‐Thienyl)‐2,2‐dimethyl‐2H‐azirins
Authors: Pfoertner Karl‐Heinz , Zell Reinhard
Published: December 2004

Synthesis and Photochemistry of 3‐(2‐Thienyl)‐2,2‐dimethyl‐2H‐azirine

The synthesis of 3‐(2‐thienyl)‐2,2‐dimethyl‐2 H‐azirine (1) is described. UV. irradiation of 1 in benzene solution generates the nitrile isopropylide 2 which reacts in a regiospecific manner with activated C, C and C, O double bonds to give 1‐pyrrolines and 3‐oxazolines, respectively. With chelidonic acid diethyl ester the cycloaddition of 2 to the C, C double bond is preferred.
Erhöhung der Nachweisempfindlichkeit von Cyclosporin A durch Derivatisierung mit 2‐Naphthylselenylchlorid
Authors: Gfeller Jean‐Claude , Beck Albert K. , Seebach Dieter
Published: December 2004

Enhancement of Detection Sensitivity of Cyclosporin A by Derivatization with 2‐Napthylselenylchloride

The UV./HPLC. detection sensitivity of cyclosporine A 1, an immunosuppressive cyclic undecapeptide containing one D‐aminoacid and seven N‐methylated aminoacids, is enhanced by a factor of 3‐4 (limit of detection 5 ng) by conversion of the characteristic side chain of amino‐acid‐1 to the β‐naphthylseleno‐substituted tetrahydrofuran derivative 4.
(Butadiene)tricarbonylosmium synthesis and structural comparison with the Fe‐ and Ru‐complexes based on 1H‐ and 13C‐NMR. Spectroscopy
Authors: Zobl‐Ruh Susanne , Von Philipsborn Wolfgang
Published: December 2004

The photochemical synthesis of the title complex from 1,3‐butadiene and dodecacarbonyltriosmium is described. The 1H‐NMR. and H‐coupled 13C‐NMR. spectra are analyzed completely and the H, H‐ and C,H‐coupling constants compared with the data of the corresponding Fe‐ and Ru‐complexes. One‐bond 13C, 13C‐coupling constants are reported for a series of complexed 1,3‐dienes. All data are consistent with an increasing distortion from planarity of the C,H‐skeleton at the terminal diene C‐atoms in the sequence Fe → Ru → Os.
Die Synthese von 6exo‐substituierten p‐Toluolsulfonsäure‐[2endo‐norbornyl]estern. Norbornanreihe, 2. Mitteilung
Authors: Fischer Walter , Grob Cyril A. , Von Sprecher Georg , Waldner Adrian
Published: December 2004

The synthesis of 6exo‐Substituted 2endo‐Norbornyl p‐Toluenesulfonates

The preparation of hitherto unknown p‐toluenesulfonates of 6exo‐substituted 2endo‐norbornanols is described.
The Rates of Diazomethane Formation from Methylnitrosoamides. The stability of diazomethane solutions towards aqueous alkalis
Authors: Pearce Michael
Published: December 2004

The rate of hydrolysis of N‐methyl‐N‐nitrosoamides by aqueous alkalis varies greatly. Methylnitrosourea (1) is hydrolyzed rapidly by aqueous KOH‐solutions at low temperatures to give a high yield of diazomethane. Under similar conditions, N,N′‐dimethyl‐N,N′‐dinitroso‐oxamide (3) is hydrolyzed more slowly, but also gives a good yield of diazomethane. N,N′‐Dimethyl‐N,N′‐dinitrosoterephthal‐amide (4), and (N‐methyl‐N‐nitroso)‐4‐amino‐4‐methyl‐2‐pentanone (5) are less easily hydrolyzed by aqueous KOH‐solutions. N‐Methyl‐N‐nitroso‐p‐toluenesulfonamide (2) was the least reactive out of those tested. The hydrolysis of diazomethane in toluene with aqueous bases follows first order kinetics. The hydrolysis rate is greatly influenced by the concentration and strength of the base and temperature.
Über die Temperaturabhängigkeit der 13C‐NMR.‐Spektren von Tetracarbonyl (η‐(Z)‐cycloocten)eisen und (Z)‐cycloocten
Authors: Von Büren Martin , Cosandey Marcel , Hansen Hans‐Jürgen
Published: December 2004

On the Temperature Dependence of the 13C‐NMR.‐Spectra of Tetracarbonyl (η‐(Z)‐cyclooctene)iron and of (Z)‐Cyclooctene

Reaction of (Z)‐cyclooctene (1) with Fe2(CO)9 in pentane at 0° yielded tetracarbonyl(η‐(Z)‐cyclooctene)iron (2) as a yellow oil which can be stored over a longer period only at −78°.

It is shown that the title compounds (1 and 2, respectively) are fluxional.

The activation parameters for the conformational C‐atom site exchange of (Z)‐cyclooctene (1) and tetracarbonyl (η‐(Z)‐cyclooctene)iron (2) (in CCl2F2) have been determined between 113 K and 151 K for 1 and between 151 K and 205 K for 2, respectively, by a complete line shape analysis of the temperature dependent proton noise‐decoupled 13C‐NMR. signals of the olefinic C‐atom. The kinetic data and activation parameters are given in Tables 1 and 2.
The Synthesis of Cystine Peptides by Iodine Oxidation of S‐Trityl‐cysteine and S‐Acetamidomethyl‐cysteine Peptides
Authors: Kamber Bruno , Hartmann Albert , Eisler Karel , Riniker Bernhard , Rink Hans , Sieber Peter , Rittel Werner
Published: December 2004

Previously reported studies of the iodine oxidation of S‐trityl‐cysteine peptides and S‐acetamidomethyl‐cysteine peptides, leading directly to cystine peptides, have been extended. Detailed investigations have been made of the reactivities of the S‐trityl and the S‐acetamidomethyl group towards iodine in various solvents. In chloroform, methylene chloride, trifluoroethanol, and hexafluoroisopropyl alcohol the differences in the reaction rates of the two groups have been found to be extremely large, allowing the selective conversion of the tritylthio groups to disulfides in the presence of the S‐acetamidomethyl derivatives. In a second group of solvents, consisting of methanol, acetic acid, dioxane, and mixtures of these solvents with water, simultaneous iodine oxidation of S‐trityl‐ and S‐acetamidomethyl‐cysteine peptides leads to a preferential combination of these two residues, resulting in predominantly asymmetrical cystine derivatives. ‐ The suitability of the two sulfur‐protecting groups in the synthesis of cyclic cystine peptides has been assessed. ‐ Possible reaction mechanisms are discussed. ‐ The scope and limitations of iodine oxidation in peptide synthesis have been studied.

The applicability of the method has been demonstrated in the preparation of the open‐chain asymmetrical cystine peptide 5, the protected somatostatin derivative 17, and the A(1–13) segment 19 of human insulin, previously employed in the total synthesis of this hormone.
Die Hydrolyse von 6exo‐substituierten 2exo‐ und 2endo‐Norbornylestern der p‐Toluolsulfonsäure. Norbornanreihe. 3. Mitteilung
Authors: Fischer Walter , Grob Cyril A. , Von Sprecher Georg , Waldner Adrian
Published: December 2004

The Hydrolysis of 6exo‐Substituted 2exo‐ and 2endo‐Norbornyl p‐Toluenesulfonates. Norbornane Series. Part 3

Hydrolysis of the 6exo‐substituted 2exo‐ and 2endo‐norbornyl p‐toluenesulfonates 1b‐1 and 2b‐1, respectively, in 70% dioxane led to different amounts of the following products: Unrearranged 2exo‐norbornanols 3 and norbornenes 5, accompanied in somes cases by small amounts of the rearranged Rendo‐epimers 4 and 6 and by norticyclenes 7. When the 6exo‐substituent was a nucleophilic group as in 1e‐1 and 2e‐1, various amounts of tricyclic products were also formed by endo‐cyclization. These results show that the 2exo‐ and 2endo‐esters 1 and 2, respectively, react by way of different intermediates. In cases where the 6exo‐substituent was an n‐electron donor, as in 1m‐r and 2m‐r, quantitative fragmentation to (3‐cyclopentenyl)acetaldehyde (13) occurred.
The Homoallyl‐Cyclopropylcarbinyl Cation Rearrangement in the Solvolyses of exo‐ and endo‐5‐Norbornen‐2‐yl p‐Bromobenzenesulfonates. Application of 2H‐NMR. Spectroscopy
Authors: Burger Ulrich , Sonney Jean‐Marie , Vogel Pierre
Published: December 2004

The buffered trifluoroethanolyses and acetolyses of exo‐(2‐D)‐ (6) and endo‐(2‐D)‐5‐norbornen‐2‐yl brosylates (7) yielded exo‐5‐norbornen‐2‐yl and 3‐nortricyclyl derivatives. The deuterium distribution in these products was determined unambiguously by 2H‐NMR. and MS. In contrast to previous reports, each hydrogen and, consequently, each deuterium atom could be identified. Product ratio and label distribution in the solvolysis of 6 make unnecessary the intervention of asymmetrical homoallylic cation intermediates. The results are most economically rationalized by invoking symmetrical 3‐nortricyclyl ion‐pair intermediates.
Optical activity in remotely perturbed exocyclic s‐cis‐butadienes. Preparation and circular dichroism of enantiomerically pure 5,6‐dimethylidene‐2‐norbornyl derivatives
Authors: Sonney Jean‐Marie , Vogel Pierre
Published: December 2004

Optically pure 5, 6‐dimethylidene‐exo‐2‐norbornanol ((+)‐1), acetate ((+)‐2), p‐bromobenzenesulfonate ((+)‐3), 5, 6‐dimethylidene‐endo‐2‐norbornanol ((+)‐4), acetate ((+)‐5), p‐bromobenzenesulfonate ((+)‐6) and 5, 6‐dimethylidene‐2‐norbornanone ((+)‐7) have been prepared. Their chirality was correlated chemically with that proposed by Mislow et al. for (+)‐benzo‐5‐norbornen‐2‐yl acetate ((+)‐14). The solution CD. spectra of these remotely perturbed exocyclic s‐cis‐butadienes are reported and discussed briefly. Unexpectedly, the β,γ‐unsaturated ketone (+)‐7, for which transannular interaction between the ketone and diene functions was revealed by its UV. absorption spectrum, showed (in isooctane) two weak Cotton effects of opposite sign between 265 and 340 nm.
Classification of the CD. Spectra of carotenoids
Authors: Sturzenegger Verena , Buchecker Richard , Wagnière Georges
Published: December 2004

The CD. spectra of carotenoids in the 220‐500 nm region may by inspection be classified as (a) essentially Conservative, (b) intermediate, or (c) essentially nonconservative. A conservative spectrum shows in that spectral region a sequence of 5‐6 relatively sharp Cotton effects of alternating sign, the rotatory strengths of which roughly add to zero. In a non‐conservative spectrum Δϵ has the same sign over the whole region and its absolute value is in general somewhat smaller. In general, typical conservative spectra invert upon isomerization of the molecule from all‐trans to mono‐cis. Non‐conservative spectra do not invert. The model of a chiral polyene of the length of the conjugated carotene chromophore reproduces well the main features of the conservative spectra. The theoretical predictions and the experimental data are shown to conform to the C2‐rule [43] [44]. The particular nature of the longest‐wavelength transition is interpreted. Based on a summary of the chiroptic data on about 50 naturally occurring compounds, the question is discussed of when conservative spectra arise and when not.
An Efficient Synthesis of 2,3,5,6‐Tetramethylidene‐7‐oxanorbornane
Authors: Mahaim Cyril , Carrupt Pierre‐Alain , Hagenbuch Jean‐Pierre , Florey André , Vogel Pierre
Published: December 2004

Palladium‐catalyzed double carbomethoxylation of the Diels‐Alder adduct of furan and maleic anhydride yielded the methyl all‐exo‐7‐oxanorbornane‐2,3,5,6‐tetracarboxylate (7) which was transformed in three steps into 2,3,5,6‐tetramethylidene‐7‐oxanorbornane (1), a useful synthon. Six isomeric methyl 7‐oxanor‐bornane‐2,3,5,6‐tetracarboxylates (7–12) have been isolated and their 1H‐ and 13C‐NMR. data are compared.
«3‐Fluorisopren» (2‐Fluor‐3‐methyl‐1,3‐butadien) und einige heterosubstituierte Abkömmlinge
Authors: Schlosser Manfred , Spahie Bojana
Published: December 2004

‘3‐Fluoroisoprene’ (2‐Fluoro‐3‐methyl‐1,3‐butadiene) and Some Hetero‐substituted Derivatives Thereof

The readily accessible 1‐chloro‐1‐fluoro‐2‐iodomethyl‐2‐methylcyclopropane undergoes zinc‐promoted ring‐cleavage yielding 2‐fluoro‐3‐methyl‐1, 3‐butadiene (‘3‐fluoroisoprene’) in almost quantitative yield. Alternatively the iodine atom may be replaced by electron‐attracting groups such as cyano, benzenesulfonyl or triphenylphosphonio. Ring‐opening of the resulting derivatives can then be brought about by various bases and leads to substituted fluorodienes. ‐ The chemical reactivity of ‘3‐fluoroisoprene’ has been studied in some detail. For example, it was found to add bromine at temperatures below 0° under kinetic control and to afford mainly the 1,4‐adduct having the (Z)‐configuration besides smaller quantities of the 1,2‐ and 3,4‐adduct. At room temperature this mixture slowly undergoes a transformation yielding, as the sole products, both stereoisomeric 1, 4‐adducts in a 1:1 ratio.
Die Stereochemie der fragmentierenden Enthalogenierung von 1‐Chlor‐1‐fluor‐2‐(1‐halogenalkyl)cyclopropanen
Authors: Spahić Bojana , Schlosser Manfred
Published: December 2004

The Stereochemistry of the Fragmentative Dehalogenation of 1‐Chloro‐1‐fluoro‐2‐(1‐halogenalkyl)cyclopropanes

A number of model substrates were submitted to zinc‐promoted fragmentation, and the composition of the resulting mixture of isomeric fluorodienes was determined. The exocyclic reaction center, bearing the electrofugal leaving group, was found to undergo almost complete stereochemical randomization in the course of the reaction. On the other hand, the ring‐opening proceeds stereoselectively. The rotation, which brings the substitutents of the halogen‐free ring position into the plane of the new, fluorine‐bearing double‐bond, occurs mainly in that sense to move the electrons of the breaking ring linkage into the rear of the departing chlorine atom.
Halochrome Molekeln 3. Mitteilung [1]. Thermodynamische und kinetische Untersuchungen zum acidobasischen Verhalten substituierter 6,6‐Diphenyl‐6H‐chromeno[4,3‐b]indole
Authors: Hellrung Bruno , Balli Heinz
Published: December 2004

Halochromic Molecules. Thermodynamics and Kinetics of the Acidobasic Behaviour of Substituted 6,6‐Diphenyl‐6H‐Chromeno [4,3‐b]Indoles

The complex halochromic behaviour of substituted 6, 6‐Diphenyl‐6 H‐chromeno‐[4,3‐b]indoles was investigated by stopped flow techniques and spectrometric methods in 64% methanol/water mixtures at 25°. pK‐values are determined, rates and mechanisms of coloration reaction are investigated and results are discussed.
Crystal and Molecular Structure of (±)‐8,8‐Dimethyl‐6,7‐diazabicyclo[3.3.0]octa‐1,6‐diene 7‐oxide
Authors: Maverick Andrew W. , Maverick Emily F. , Olsen Henrik
Published: December 2004

The exclusive product of thermal rearrangement of (±)‐7‐isopropylidene‐2,3‐diazabicyclo[2.2.1]hept‐2‐ene N‐oxide (2) has been identified as the title compound (1). The compound crystallizes in the orthorhombic space group Pbca (No. 61), with a= 8.953 (2), b= 12.740 (2), c=14.446 (3) Å; Z= 8; px=1.227 g cm−3. The details of the molecular structure are not unusual, except for a long C–N distance (C(8)–N(7), 1.560 (4) Å). No significant short intermolecular contacts are observed in the crystal.
Synthèse partielle et propriétés oncostatiques des pseudo‐tubulosines, analogues de l'émétine et de la tubulosine
Authors: Seguin Elisabeth , Koch Michel , Chenu Evelyne , Hayat Marcel
Published: December 2004

Partial Synthesis and Oncostatic Properties of Pseudotubulosines, Analogues of Emetine and Tubulosine

Pseudotubulosines, structural analogues of emetine and tubulosine, have been synthesized by either Pictet‐Spengler or Bischler‐Napieralski condensation from dihydrocorynantheal or corynantheidal. Spectral data, cytotoxic and oncostatic properties of these new alkaloids are described.
Glutamate and prostaglandin E2in the trapezius muscle of female subjects with chronic muscle pain and controls determined by microdialysis
Authors: Flodgren Gerd M. , Crenshaw Albert G. , Alfredson Häkan , Fahlström Martin , Hellström Fredrik B. , Bronemo Lars , Djupsjöbacka Mats
Published: December 2004

Much is still unknown concerning the mechanisms underlying the development of chronic muscle pain. The presence and magnitude of inflammatory substances and neurotransmitters in chronic painful conditions is not clear. The aims of the present study were to determine, with the use of microdialysis, the interstitial concentrations and the equilibration times for PGE2and glutamate in the trapezius muscles of nine female subjects with chronic muscle pain, and nine pain‐free age‐matched controls. A microdialysis probe was implanted in the upper part of the trapezius muscle and perfused with Ringer‐acetate solution at a flow rate of 0.3 μL/min. Samples were obtained every 30 min, during a 4‐h rest period. At equilibration, the mean concentrations (−SE) of PGE2were 0.71 (−0.11) ng/mL for the pain‐group and 0.97 (−0.35) ng/mL for the controls. For glutamate the mean concentrations for the pain‐group were 66.3 (−13.3) μmol/L and 60.6 (−22.9) μmol/L for the controls. For the pain group and the control group, respectively, equilibration for PGE2was reached at 180 and 150 min, and for glutamate at 150 and 120 min. The present study showed no differences between groups in the concentrations of PGE2and glutamate in the trapezius muscle. Further, it revealed that when using the slow‐flow method, a period of at least 2.0‐2.5 h is needed, after probe insertion, to reach steady state for glutamate and PGE2.
Central pain in multiple sclerosis — prevalence and clinical characteristics
Authors: Österberg A. , Boivie J. , Thuomas K.‐Å.
Published: December 2004

Pain is more common in multiple sclerosis (MS) than has previously been recognised. In the present study we have investigated the occurrence of central pain (CP) in MS and defined its characteristics. Questionnaires were sent to all 429 patients with definite MS in the patient register at our neurology department. All admitting to pain were interviewed and offered an extended interview and examination. Three hundred and sixty four patients responded (86%), of whom 57.5% reported pain during the course of their disease (21% nociceptive, 2% peripheral neuropathic and 1% related to spasticity). One hundred patients (27.5%) had CP, including 18 patients (4.9%) with trigeminal neuralgia.

The non‐trigeminal CP was, in 87%, located in the lower and in 31% in the upper extremities. It was mostly bilateral (76%) and constant, with 88% experiencing daily pain. Only 2% had paroxysmal attacks. Aching, burning, pricking were the commonest qualities. The pain was intense with small to moderate spontaneous variation. In 5.5% of all patients (20% of the patients with CP), pain was a presenting symptom, alone or in combination with other symptoms.

The most common neurological symptoms/signs besides CP were sensory abnormalities (98%, dominated by abnormal sensibility to painful stimulus and temperature). Trigeminal neuralgia in MS started later in life and after longer disease duration than non‐trigeminal pain. Both types of CP existed either chronically or as a feature of relapse. Central pain is thus an important symptom in MS (around 30%) and causes much suffering.