bluuebunny/crossref_metadata_2025 huggingface dataset:
Alkylaminopyridines and some Analogues as Derivatives for the structure elucidation of long aliphatic chains by mass spectrometry
Authors: Vetter Walter , Meister Walter , Oesterhelt Gottfried
Published: December 2004

Several long chain primary alcohols (saturated, monoolefinic and methyl branched) have been converted via their mesylates into various long chain alkylated aromatic compounds with basic character, and their mass spectra compared. The spectra of 2‐alkylaminopyridines and to some extent those of 3‐alkylaminopyridines exhibit most clearly the structure of the aliphatic chain, allowing the localization of branchings and double bonds.
The Unexpectedly Stable Dianion of a Naphthalene‐Tolan Photoadduct
Authors: Müllen Klaus
Published: December 2004

Metal reduction of the polycycle 2 yields a surprisingly stable dianion with intact molecular framework. This conclusion can be drawn from reoxidation experiments and from an analysis of the 1H‐NMR. spectrum. The excess charge turns out to be distributed over both the π‐ and σ‐fragments of the molecule. The relative stabilities of ionic species derived from 1, 2 and 3 are considered.
Résonance magnétique nucléaire de 13C et 17O d'éthers aliphatiques. Effets γ entre les atomes d'oxygène et de carbone
Authors: Delseth Claude , Kintzinger Jean‐Pierre
Published: December 2004

The 13C‐ and 17O‐chemical shifts of 31 aliphatic ethers are measured and discussed. The 17O‐chemical shifts of the ethers ROR′ correlate with chemical shifts for the methylene groups of the corresponding alkanes RCH2R′. The constant of proportionality can be related to the orbital expansion term 〈r−3〉2p. The δc for carbon atoms can also be correlated with δc for the corresponding alkanes. The origin of the correlation is discussed taking into account the conformational modifications resulting from introduction of an oxygen atom in an alkyl chain.
Die «Zip»‐Reaktion: Eine neue Ringerweiterungsreaktion. Synthese von 17‐, 21‐ und 25‐gliedrigen Polyaminolactamen. 4. Mitteilung über Umamidierungsreaktionen
Authors: Kramer† Urs , Guggisberg Armin , Hesse Manfred , Schmid† Hans
Published: December 2004

The Zip‐reaction: A New Method for the Synthesis of Macrocyclic Polyaminolactams

The 21‐ and 25‐membered aminolactams 11 and 25 were synthesized from the 13‐membered lactam 4. To introduce the ring enlargement unit (a propylamino group) 4 was N‐alkylated using acrylonitrile and the resulting product hydrogenated. Repetition of this reaction sequence gave 3, which was converted in the presence of base in 90% yield to the ring‐enlarged macrocyclic base 11 (Scheme 2). In a similar but stepwise synthesis consisting of two separate ring‐enlargement reactions 4 was transformed to 11 via 13 (Scheme 4). Introducing three ringenlargement units into 4 the 25‐membered aminolactam 25 was synthesized in 84% yield (Scheme 5). The mechanism of the ring‐enlargement reaction is given in Scheme 3. In comparison to a zip‐fastener or zipper this reaction is called “zipreaction”.
Zur Kenntnis der Indolreaktion nach Fischer. II. Thermische und säurekatalysierte Indolisierung von 1′‐Alkenyl‐2′‐methyl‐2′‐phenylacetohydraziden
Authors: Schiess Peter , Sendi Ebrahim
Published: December 2004

On the Fischer‐Indole Reaction. II. Thermal and Acid Catalysed Indolization of 1′‐Alkenyl‐2′‐methyl‐2′‐phenylacetohydrazides

Seven different 1′‐alkenyl‐2′‐methyl‐2′‐phenylacetohydrazides, 6a‐g, have been prepared by treatment of the methylphenylhydrazones 7 of appropriate ketones and aldehydes with acetyl chloride in pyridine. At 170° 6a‐g are transformed into the N‐methylindoles 3a‐g and acetamide in moderate yield. N‐Methylaniline is the other major reaction product indicating that homolytic cleavage of the weak N, N‐bond in 6 is a major primary reaction step. It is likely but not proven that the N‐methylindoles 3 are formed in a reaction sequence initiated by an uncatalysed concerted [3, 3]‐sigmatropic rearrangement.

Upon treatment of 6 with 0.5N dichloroacetic acid in anhydrous acetonitrile at room temperature a quantitative conversion to 3 is observed, interpreted as proceeding by a charge induced [3, 3]‐sigmatropic rearrangement of protonated 6 in the rate determining step. The ketone derivatives 6a‐e (R1 = alkyl) react 40‐1000 times faster with acid than the aldehyde derivatives 6f and 6g (R1 = H). This is rationalized as a consequence of the increased basicity of 6a‐e relative to 6f and 6g caused by a steric effect.
Contribution à la phytochimie de genre Gentiana. XXIV.. Nouveaux C‐glycosides flavoniques dans les feuilles de Gentiana asclepiadeaL.
Authors: Goetz Michel , Jacot‐Guillarmod André
Published: December 2004

Phytochemistry of genus Gentiana, XXIV. New C‐glycosylflavones from the leaves of Gentiana asclepiadea L.

p‐Hydroxybenzoyl‐2″‐isoorientin‐4′‐O‐β‐D‐glucoside (1) was isolated from the leaves of Gentiana asclepiadea L. by means of column chromatography. This is the first occurrence in nature of a p‐hydroxybenzoate of isoorientin. p‐Hydroxybenzoyl‐2″‐isoorientin (2) was also shown to be present in the same plant.
Heterocyclic Spiro‐naphthalenones. Part II. Synthesis and reactions of some spiro [tetrahydrofuran‐2,1′‐(2′H‐naphthalene)]‐2′,5‐diones and Spiro [tetrahydrofuran‐2,2′‐(1′H‐naphthalene)]‐1′,5‐diones
Authors: Berney Daniel , Schuh Karlheinz
Published: December 2004

The spiro‐lactone 3 was obtained by N‐bromosuccinimide (NBS) oxidation of the carboxylate 2 at − 20°. When 2 was oxidized at 10° the spiro‐lactone 4 was the main product. Compound 4 was rearranged with triethylamine to the spiro‐lactone 9 whereas the stereoisomeric spiro‐lactones 14 and 15 were obtained by NBS oxidation of the carboxylate 13. The ketones 3, 4, 9, 14 and 15 were reduced with NaBH4 to the corresponding alcohols 5, 6, 10, 16 and 18 respectively; these were hydrogenated to the alcohols 7, 8, 11 and 20. The allylic alcohols 5 and 6 gave the benzochromanone 1 when heated in polyphosphoric acid whereas the benzochromanones 12 and 21 were obtained from the alcohols 10 and 16 respectively.
Enamines I. Vinyl Amine, a Theoretical Study of its Structure, electrostatic potential, and proton affinity
Authors: Müller Klaus , Brown Leo D.
Published: December 2004

The structure of vinyl amine and its reactivity towards a proton is studied by the PRDDO SCF MO method. The equilibrium structure is found to be non‐planar and barriers to inversion‐ and rotation‐dominated processes are calculated. Proton addition to vinyl amine, as a model of enamine protonation, is examined by means of electrostatic molecular potentials and C‐ versus N‐proton affinities.
The Inversion of the Amino Group in Vinylamine, a Flexible Model Treatment
Authors: Meyer Rolf
Published: December 2004

Flexible model results for the NH2 inversion in vinylamine are compared with microwave data published by Lovas et al. [3]. The information available on the spacing of inversion levels is found to be sufficient to rule out a planar equilibrium structure. Shifts of rotational constants upon excitation of the inversion are calculated for two predicted paths of motion derived from PRDDO geometry optimization results obtained by MiiIler & Brown [2]. Partial geometry optimization yields a path inconsistent with experiment but the path obtained from complete optimization produces shifts in excellent agreement with the observed shifts. A potential energy function compatible with experimental data on spacing of inversion levels is calculated from the observed inertia defects. The inversion angle at equilibrium is slightly smaller than the angle predicted from PRDDO calculations, and the barrier to inversion, ΔV = 1.08 ± 0.07 kcal/mol, is approximately half the PRDDO value.
Identification de stérols à chaînes latérales courtes dans l′éponge Damiriana hawaiiana
Authors: Delseth Claude , Carlson R. M. K. , Djerassi Carl , Erdman Timothy R. , Scheuer Paul J.
Published: December 2004

Identification of short side chain sterols in the sponge Damiriana hawaiiana

The steroidal composition of the sponge Damiriana hawaiiana is examined. Twenty‐seven components are identified. In addition to the C26‐C29, Δ5‐mono and diunsaturated sterols, the sponge contains sterols without side‐chain: androsta‐5, 16‐dien‐3β‐ol(1), androst‐5‐en‐3β‐ol(2); sterols with a non‐functionalized side‐chain consisting of two, three, four, five and six carbon atoms: pregna‐5, 20‐dien‐3β‐ol(5), pregn‐5‐en‐3β‐ol(6), 23, 24‐bisnor‐chola‐5, 20‐dien‐3β‐ol(7), 23, 24‐bisnor‐chol‐5‐en‐3β‐ol(8), 24‐nor‐chol‐5‐en‐3β‐ol(10), chol‐5‐en‐3β‐ol(11), 26, 27‐bisnor‐cholest‐5‐en‐3β‐ol(12), and sterols possessing a short oxygenated side‐chain such as 3β‐hydroxy‐androst‐5‐en‐17‐one(3), androst‐5‐en‐3β, 17β‐diol(4) and 3β‐hydroxy‐26, 27‐bisnor‐22‐trans‐cholesta‐5, 22‐dien‐24‐one(14). The probable biological or dietary origin rather than artifact production of these hitherto undescribed components from marine sources is supported by their relatively high concentration and their relative proportions, both very different from those expected for autoxidation.
Zum photochemischen Verhalten von Sydnonen und 1,3,4‐Oxadiazolin‐2‐onen. 56. Mitteilung über Photoreaktionen
Authors: Märky Michael , Meier Hansruedi , Wunderli Alfred , Heimgartner Heinz , Schmid Hans , Hansen Hans‐Jürgen
Published: December 2004

On the Photochemistry of Sydnones and 1,2,3,4‐Oxadiazolin‐2‐ones

The photochemical behaviour of several 3,4‐disubstituted sydnones (cf. Scheme 5) dioxane solution was investigated. The pure sydnones give, as was already reported [2–6], 2,4,5‐trisubstituted 1,2,3‐triazoles 2 (cf. Scheme 1) in 25–30% yield. In the presence of dipolarophiles (cf. Scheme 1) pyrazole derivatives 3 or 4 are formed which can be taken as a proof for the formation of nitril‐imines 5 as primary products in sydnone photochemistry. Since irradiation of 2‐[15N]‐3, 4‐diphenyl‐sydnone (2‐[15N]‐15) in dioxane leads to the formation of 1,3‐[15N]‐2,4,5‐triphenyl‐1,2,3‐triazole (1,3‐[15N]22; cf. Scheme 10), nitril‐imine formation must be induced by the creation of a bond between N(2) und C(4) in the excited sydnones (cf. Scheme 22). The irradiation of sydnones in dioxane solution in the presence of carboxylic acids yields N′‐acylhydrazides in 50–70% (cf. Scheme 14), the formation of which can be explained by addition of the acids to the nitril‐imines and rearrangement of the primarily formed anhydride monohydrazones (Scheme 15). By analogy, the formation of 1‐benzoyl‐2‐(t‐butyl)‐4‐phenyl‐1,2‐diazetidin‐3‐one (14; Scheme 4) during the photolysis of 3‐(t‐butyl)‐4‐phenylsydnone (12) in benzene solution (cf. [5b]) may also be explained: Sydnone 12 undergoes two different photoreactions leading by loss of carbon dioxide to the corresponding nitril‐imine 5 (R=t‐C4H9, R′ C6H5) and by loss of isobutylene to a 1,2,3‐oxadiazolin‐5‐one of type 48 or 49 which isomerizes to yield diazophenylacetic acid (51; cf. Scheme 17). Reaction of both products (5 and 51) results in the formation of the N′‐acylhydrazide 52 (Scheme 18) which may cyclize after loss of nitrogen to yield the diazetidinone 14 in a carbene type reaction. The triazoles 2 are formed photochemically from the corresponding 1,2‐bisazo‐ethylenes 64 (Scheme 26) which arise from a direct ‘head‐to‐head’ dimerization of the nitril‐imines 5. This type of reaction seems to be common to all nitrilium betaines (Schema 30). The photolysis of the 2,4‐disubstituted 1,3,4‐oxadiazolines 76 does not lead to nitril‐imines 5 (cf. [11]). On the contrary, loss of carbon monoxide induces the formation of azoketones 77 (cf Scheme 31), which may be photo‐reduced to yield hydrazides or may undergo cleavage of the N, acyl bond to form derivatives of1,2‐diketones (cf. Scheme 32).
Total Synthesis of Indole and Dihydroindole Alkaloids. XV. Further Chemistry of Vindoline
Authors: Kutney James P. , Bunzli‐Trepp Ursula , Honda Toshio , Katsube Junki , Worth Brian R.
Published: December 2004

The general reactivity of various sites in the vindoline series has been investigated. The facility of electrophilic substitution at C(15) and the effect of steric crowding on reactions at C(4) are discussed. At the basic nitrogen sites, oxidations with mercuric acetate and potassium permanganate are also discussed.
Inductive, Hyperconjugative and Frangomeric Effects in the Solvolysis of 1‐Substituted 3‐Bromoadamantanes. Polar effects IV
Authors: Fischer Walter , Grob Cyril A.
Published: December 2004

Three kinds of polar substitutent effects are observable in the solvolyses of 1‐R‐substituted 3‐bromoadamantanes (VI). This follows from the relationship between products, rate constants k in 80% ethanol, and the inductive substituent constants σ of the substituent R. Alkyl groups and electron‐attracting substituents at C (1) control the rate by their inductive effects alone, since logk correlates closely with σ. However, rates are higher than predicted on the basis of the respective σ values when conjugating (+ M)‐substituents or electrofugal groups are attached to C(1). These exalted substituent effects are attributed to CC‐hyperconjugative relay of positive charge from the cationic center at C(3) to the substituent at C(1). When the substituent is a strong electron donor (e.g. O− and S−), accelerated substitution gives way to heterolytic fragmentation, rates and products then being controlled by the frangomeric effect.
Nucleoside und Nucleotide. Teil 11. Phosphorylierung von 1‐(2′‐Desoxy‐β‐D‐ribofuranosyl)‐2(1H)‐pyridon und dessen Verhalten bei der Synthese von Dinucleotiden
Authors: Waldmeier Felix , Tamm Christoph
Published: December 2004

Nucleosides and Nucleotides, Part 11. Phosphorylation of 1‐(2′‐Desoxy‐β‐D‐ribofuranosyl)‐2(1H)‐pyridon and its Behaviour in the Synthesis of Dinucleotides

The behaviour of the unnatural nucleoside 1‐(2′‐deoxy‐β‐D‐ribofuranosyl)‐2(1H)‐pyridon (Πd, 1) in the synthesis of dinucleotides with purine deoxynucleotides was studied. The optimized preparation of the protected dinucleoside phosphates (MeOTr) Πd pG (5) and (MeOTr) Πd pA (7) using the diester method of Khorana with DCC as condensing agent is described. The removal of the N‐acyl‐ and p‐methoxytrityl groups was effected by successive treatment with conc. ammonia solution and acetic acid/water 1:1 at 23° yielding the free dinucleoside phosphates ΠdpGd (9) and ΠdpAd (11). In a similar way, starting from (CNEt) pΠd(15), the dinucleotides pΠdpG (16), pΠdpGd (18), pΠdpA (17) and pΠdpAd (19) were synthesized.

The nucleotide 1‐(5′‐O‐Phosphoryl‐2′‐deoxy‐β‐D‐ribofuranosyl)‐2(1H)‐pyridon (pΠd, 3) was prepared in excellent yield by selective phosphorylation of Πd (1) using phosphorylchloride in triethyl phosphate at −40°. Deoxyadenosine was phosphorylated in the same way.

The compounds were characterized by UV. spectroscopy, chromatography and enzymatic degradation.
Eine einfache Veresterungsmethode im Eintopf‐Verfahren
Authors: Stadler Paul Albert
Published: December 2004

A simple one‐pot method for esterification

A one‐pot procedure for esterifications of primary, secondary and tertiary alcohols and of phenols in high yield is described. Reaction of oxalylchloride with dimethylformamide in a suitable solvent affords dimethylformamide imidechloride; addition of an acid to the suspension of this reagent furnishes an activated carboxy‐group derivative, which is then transformed to an ester by addition of pyridine and an alcohol ro a phenol. Reaction temperatures needed for esterification are low, usually 0° to room temperature, reaction times are short.
Über die Temperaturabhängigkeit der 13C‐NMR.‐Spektren von [5–6‐η‐(1Z, 5E)‐Cyclooctadien]tetracarbonyleisen und (1Z, 5E)‐Cyclooctadien
Authors: Von Büren Martin , Bischofberger Pius , Hansen Hans‐Jürgen
Published: December 2004

On the Temperature Dependence of the 13C‐NMR. Spectra of [5‐6‐η‐(1Z,5E)‐Cyclooctadien] and of (lZ, 5E)‐Cyclooctadiene

The activation parameters of the conformational ring inversion process (simultaneous rotation around the C(3), C(4) and C(7), C(8) bonds; cf. Scheme 1) of the title compounds (1 and 2, respectively) have been determined between 275 L and 155 K by a complete line shape analysis of the temperature dependent proton noise‐modulated decoupled 13C‐NMR. spectra of 1 and 2. The temperature dependence of the rates (k(1) and k(2), respectively) of the inversion process can be described by the following equations (no influence of the solvents was observed; Ea in J/mol):

. Further data are given in Tables 1 and 2.

The carbonyl groups of the complex 1 show at 180 K, where the ring inversion process is frozen out, a single line at 211 ppm, i. e. the coalescence temperature of the carbonyl groups must be < 180 K.
Hydroformylation of 1, 1, 1‐d3‐2‐butene. Isotope Effect on the Product Composition
Authors: Consiglio Giambattista , von Bézard Denis A. , Morandini Franco , Pino Piero
Published: December 2004

In the hydroformylation of 1,1,1‐trideuterio‐2‐butene with Rh4 (CO)12 the deuterated pentanals formed contain 75% of 5,5,5‐trideuterio‐pentanal, the rest being substantially 2,2‐dideuterio‐pentanal. On the contrary, using Co2 (CO)8 as the catalyst precursor, position 1 and 4 are formylated to the same extent.
Tricyclo[4.2.2.22,5] dodecane and Tricyclo [4.2.2.12,5]undecane. Preliminary communication
Authors: Ernst Beat , Ganter Camille
Published: December 2004

A synthesis of tricyclo [4.2.2.22,5]dodecane (19), a novel tricyclic C12H20 compound, is described. The key intermediate ketone 13 was prepared either from the C10‐photodimer 1 of cyclopentadienone or the C11‐cycloaddition products 11 and 12. 13 was also transformed to tricyclo [4.2.2.12,5]undecane (8).
Die Reaktion von 4,6‐Dinitroisophthalaldehyd und 4,6‐Dinitroisophthalonitril mit Pyridin
Authors: Adam Jean‐Marie , Hindermann Peter , Winkler Tammo
Published: December 2004

The reaction of 4,6‐dinitroisophthalaldehyde and 4,6‐dinitroisophthalonitrile with pyridine

4, 6‐Dinitroisophthalaldehyde (4) gives on reaction with pyridine 4,6‐diformyl‐3‐(1′‐pyridinio)‐1‐phenolate (5), whereas 4,6‐dinitroisophthalonitrile (7) gives under the same conditions one main product: 3‐(1′)‐pyridinio‐4, 6‐dicyano‐1‐phenolate (10) and two side products: 2‐(1′‐pyridinio)‐4, 6‐dicyano‐3‐nitro‐1‐phenolate (11) and 4, 6‐dicyano‐3‐nitro‐1‐phenol (12). The new structures were elucidated by 1H‐NMR. and 13C‐NMR. spectroscopy.
The Reaction of SnCl2 with the Complexes cis‐PtCl2 (phosphorus ligand)2 as studied by 31P and 195Pt NMR
Authors: Pregosin Paul S. , Sze Siu Ning
Published: December 2004

The reactions of SnCl2 with the complexes cis‐PtCl2P2, P=trialkyl and triaryl phosphines and phosphites, in CDCl3 and CD2Cl2 have been studied using 31P and 195Pt NMR. methods. For equimolar amounts of Sn and Pt, products of the type PtCl(SnCl3)P2 are formed with the complex geometry depending on the nature of P. For PPEt3 and P(OPh)3, further addition of SnCl2 produces trans‐Pt(SnCl3)2 complexes. The syntheses of trans‐PtCl(SnCl3) (PEt3)2 and trans‐Pt(SnCl3)2 (OPh3)2 are described.
Untersuchungen über Allylgruppenwanderungen in aliphatischen Carbenium‐Ionen
Authors: Dillenberger Zuva , Schmid Hans , Hansen Hans‐Jüren
Published: December 2004

Investigations on the Migratory Aptitude of Allyl Groups in Aliphatic Carbenium‐Ions

The acetolysis (80°) of the 4‐bromobenzenesulfonates given in Scheme 6 were investigated in regard to determine type allyl/methyl migratory aptitudes in the secondary carbenium ion a (Scheme 24). In all cases olefins (about 80%) and acetates (about 20%) were formed which can be derived from the rearranged tertiary carbenium ions b (being formed by allyl group migration) and c (being formed by methyl group migration).

Olefin A and acetate H, originated in carbenium ion a, occurred in the acetolysis mixture only in minor amounts (<2%). By acetolysis of [l4C]‐20, isolation of [14C]‐4,5‐dimethyl‐l, 3‐hexadiene ([14C]‐45), and degradation of this diene (Scheme 16) it could be shown (4 Scheme 15) that the ions b and c (Scheme 24, R1R4H) are not interconverted by a [1,2]‐hydride shift (extent < 1%). Since olefin D arises by proton loss from ion b as well as from ion c, [14C]‐4,5‐dimethyl‐l,4‐hexadiene ([14C]44 D, R1R4 H) was also degraded (cf. Scheme 15 and Scheme 17). It was found that [14C]‐44 contained 48% of the label in the methyl group at C(4) and 52% in the methyl groups at C(5), i.e. 48% of 44 is formed via the allyl migration path and 52% via the methyl migration path. In addition, acetolysis of d3‐20 and product analysis showed, that the d3‐ally1 moiety migrates as expected only in a [1,2]‐fashion. Product analysis of the acetolysis mixtures of erythro‐ and threo‐24 (cf. Scheme 19 and Tables 4 and 5) revealed that carbenium ion a must exist as an intimate ion pair (with the 4‐bromobenzenesulfonyloxy‐ion) which has lost its configuration at C(1) only partially. This is indicated by reversed ratios (1: 11 and 10: 1, resp.) in the formation of erythro‐ and threo‐2,3,4‐trimethyl‐l, 5‐hexadiene (erythro‐ and threo‐77) arising from ion b (Scheme 24, R1R3  H, R4 CH,). The acetolysis of 1,2,2,4‐tetramethyl‐4‐pentenyl4‐bromobenzenesulfonate (23) was not studied in detail, but the appearance of a seventh product in the olefin part cannot be explained by the genesis paths in Scheme 24. Thus, it may be concluded that in this case a third tertiary carbenium ion d3 (Scheme 21) is produced by cyclization of a3. Cyclizations of this type are known to occur in carbenium ions bearing β‐substituted allyl groups (see Scheme 22). The kinetic data of the acetolysis of all 4‐bromobenzenesulfonates (Table 6) are in accord with a rate determining ionization step leading to a since all activation enthalpies resp. entropies are within 25.5 L± 0.6 kcal/mol resp. −0.2 ± 1.7 e.u. The migratory aptitudes given in Table 7 show, that allyl groups migrate only slightly easier than methyl groups in ion a. This is in strong contrast to allyl substituted methylcyclohexadienyl cations (generated in the acid catalyzed dienone/phenol and dienol/benzene rearrange‐ment) which undergo exclusively [1,2]‐ally1 migrations (Schemes 3‐5).
α‐Hydroxymethylen‐verlängerte Aldehyde durch schonende Reduktion von Cyanhydrinen
Authors: Schlosser Manfred , Brich Zdenêk
Published: December 2004

α‐Hydroxymethylene Elongated Aldehydes by Partial Reduction of Cyanohydrins

After acetal‐protection of the hydroxy group, a number of cyanohydrins (derived from aldehydes or ketones) were reduced and hydrolysed to afford α‐hydroxyaldehydes in good yields. Other synthetically useful reactions of the intermediate α‐cyano and α‐formyl acetals have also been studied.
The Enantioselective Synthesis of 3‐Methoxy‐1, 3, 5 (10)‐estratrien‐11, 17‐dione by a Thermal Intramolecular Cycloaddition Reaction. Preliminary communication
Authors: Oppolzer Wolfgang , Bättig Kurt , Petrzilka Martin
Published: December 2004

The enantiomerically pure (+)‐3‐methoxy‐1, 3, 5 (10)‐estratrien‐11, 17‐dione 11 (with trans‐anti‐trans configuration) was synthesized in a highly stereocontrolled fashion from (±)‐t‐butyl 4‐methoxy‐1‐benzocyclobutene carboxylate (8) and the (+)‐carboxylic acid 6, obtained from 4 in two steps, followed by one crystallization of the (+)‐ephedrine salt. The key step 10→11 (Scheme 2) involves a thermal intramolecular cycloaddition reaction.
Stoffwechselprodukte von Mikroorganismen. 174. Mitteilung Eine neue Synthese des Ferrichroms; enantio‐Ferrichrom
Authors: Naegeli Hans‐Ulrich , Keller‐Schierlein Walter
Published: December 2004

Metabolites of Microorganisms. A New Synthesis of Ferrichrome; enantio‐Ferrichrome

The enantiomer of the natural sideramine ferrichrome was synthesized starting from D‐ornithine. The cyclohexapeptide (D‐Orn)3‐Gly3 was obtained by conventional methods of polypeptide chemistry. For the oxidation of the δ‐amino groups of the D‐ornithine residues to hydroxylamino groups the oxaziridine pathway was successful. The final steps ‐ introduction of the acetyl groups and formation of the iron trihydroxamate complex ‐ followed known procedures. The spectroscopic and chromatographic properties of the crystalline product corresponded to those of natural ferrichrome, the optical rotations and CD. curves being opposite. The biological activity of enantio‐ferrichrome was similar to that of the natural sideramine.
Approaches to the total synthesis of cytochalasans. A convergent synthesis of the octahydroisoindolone moiety related to proxiphomin. Preliminary communication
Authors: Schmidlin Tibur , Tamm Christoph
Published: December 2004

The octahydroisoindolone moiety related to proxiphomin (1) has been synthesized by condensation of N‐benzyloxycarbonyl‐protected D, L‐phenylalaninal (7) with methyl‐(4‐methyl‐sorbyl)‐malonate (11) to yield the branched ethylene derivative 12. Consecutive intramolecular [2+4]‐cycloaddition and lactam ring closure of 12 gave the desired octahydroisoindolone derivative 15, possessing adaptable functional groups for the attachment of the macrocyclic ring system.
15N‐NMR. Spectra of pterins and folic acid derivatives
Authors: Schwotzer Willi , Bieri Jost H. , Viscontini Max , von Philipsborn Wolfgang
Published: December 2004

15N‐Chemical shifts of a series of 5, 6, 7, 8‐tetrahydropterins, 7, 8‐dihydropterins and pterins have been measured in acidic solution by means of a probe for 20 mm sample tubes. Included are the relevant data of folic acid (11), 5, 6, 7, 8‐tetrahydrofolic acid (5) and N (5, 10)‐metheno‐5, 6, 7, 8‐tetrahydrofolic acid (6). The different oxidation states are clearly relected in the chemical shifts of N (5) and N (8). Assignment of the nitrogen resonances was achieved by protonation effects (discrimination between N (1) and N (3)) and with the aid of alkyl substitution at C (6) and C(7), to distinguish between N (5) and N (8).
The fluorescence of biliverdin dimethyl ester
Authors: Braslavsky Silvia E. , Holzwarth Alfred R. , Lehner Harald , Schaffner Kurt
Published: December 2004

Freshly prepared solutions of biliverdin dimethyl ester (2) in ethanol showed fluorescence maxima at 710 and 770 nm [ΦF = 1.1. 10−4 (room temperature) and 5.0 10−4 (77 K)]. The maxima of monoprotonated 2 at 77 K were shifted to 725 and 806 nm and the quantum yield was increased to 2.6. 10−2. This acid effect was reversible by neutralization with base. When a neutral solution was kept standing in the dark at room temperature, or when an acidic solution was neutralized by base, an additional fluorescence maximum at 500 nm with a mirror image excitation spectrum with λmax = 470 nm developed, which disappeared on addition of acid and which is attributed to a chemical change of 2.
Concerning the configuration of the side chain in the antibiotic pluramycin A. Preliminary communication
Authors: Séquin Urs , Ceroni Mario
Published: December 2004

The configuration of the side chain in the antibiotic pluramycin A is shown to be cis for the olefin and trans for the epoxide (cf. 4).
Synthèse d'alcools acétyléniques par alkylation d'hydroxy‐ω‐alkynes‐1
Authors: Flahaut Jacques , Miginiac Philippe
Published: December 2004

Synthesis of acetylenic alcohols by alkylation of ω‐hydroxy‐1‐alkynes

In liquid ammonia and with lithium amide, the alkylation of an ω‐hydroxyl‐alkyne proceeds with good yield with primary or secondary alcohols and with fair yield with tertiary alcohols. It is a very convenient way to prepare many substituted acetylenic alcohols.
The Radical Anions of [2.2.2.2]Paracyclophane‐1,9,17,25‐tetraene and Some of its Heteroaromatic Analogues
Authors: Gerson Fabian , Huber Walter , Wennerström Olof
Published: December 2004

The radical anions of [2.2.2.2]paracyclophane‐ 1,9,17,25‐tetraene (I), [2] (2, 5)‐furano [2]paracyclo [2] (2,5)furano [2]paracyclophane‐1,8, 16,23‐tetraene (II), [2]‐(2,5)thiopheno [2]paracyclo [2] (2,5)thiopheno [2]paracyclophane‐1,8,16,23‐tetraene (III) and [2.2.2.2](2,5)thiophenophane‐1,8,15,22‐tetraene (IV) have been studied by ESR. and ENDOR. spectroscopy. The assignment of the proton coupling constants, aHμ is to a large extent based on investigations of deuteriated derivatives. These investigations impressively demonstrate the potential of ENDOR. spectroscopy as an analytical tool. The Arrhenius activation energies, Ea, for the rotation of phenylene fragments about the bonds linking them with the ethylenic parts in I⊖ and II⊖ are 36±6 and 28±4 kJ/mol, respectively. The value aHμ of the olefinic protons in I⊖ appears substantially smaller than expected for the corresponding planar radical anion. The hyperfine data for II⊖, III⊖ and IV⊖ are consistent with the conformations which should minimize the deviations of the macrocyclic π‐systems from planarity. In the case of II⊖, tight ion pairs are formed by the radical anion and its counter‐ion, K⊕, in DME, owing to the strong association of the alkali metal cation with one of the furan moieties. An analogous interaction of K⊕ with a thiophene moiety in III⊖ must be weaker, since no effects of ion pairing on the ESR. and ENDOR. spectra have been observed for this radical anion.
Syntheses and Cyclization Reactions of Bifunctional 1,2‐Bis (styryl)benzenes and Some Aza Analogues. Macrocyclic aza compounds. V
Authors: Ehrensperger Carl‐Peter , Heberlein Manfred , Skrabal Peter
Published: December 2004

The syntheses of the bis (styryl)benzenes 4 and 5 and of the aza analogue 3 are described. Diamine 3 and dialdehyde 5 were cyclized to the 14‐membered macrocycles 19 and 27, respectively. Diamine 4 and glyoxal give the 28‐membered macrocycle 28. The cyclizations are discussed.
Photochemische Reaktionen. 98. Mitteilung. Photochemistry of N‐Acylimidazoles. III. Rates and Yields of N→C Acyl Migration and of C(α)‐C(β) Cleavage of Acyl Side Chains
Authors: Yatsunami Takashi , Iwasaki Shigeo
Published: December 2004

Relative rates of the photoreactions of 1‐(1), 2‐(2) and 4(5)‐valerylimidazole (3) as well as the yields of photo‐fragmentation product 10 from 1‐(7), 2‐(8) and 4(5)‐stearoylimidazole (9), respectively, were determined. A reaction path via Norrish Type II fragmentation involving the carbonyl group of 1‐acylimidazoles was ruled out.
New Sesquiterpene Alcohols from Galbanum Resin; the occurrence of C (10)‐epi‐sesquiterpenoids
Authors: Thomas Alan F. , Ozainne Michel
Published: December 2004

(+)‐β‐Eudesmol (7), (+)‐10‐epi‐elemol (8), (−)‐(Z)‐dihydrofarnesol (3), and an alcohol believed to be a guai‐9‐en‐11‐ol (4) have been isolated from Galbanum resin. Together with (‐)‐β‐dihydroagarofuran (1) and epi‐ligulyl oxide (13) (reported naturally occurring for the first time), 10‐elemol (8) and 10‐epi‐junenol (2) involve the enantiomeric stereochemistry at C (10) compared with β‐eudesmol 7, and guaiol 5, the major sesquiterpene alcohol of Galbanum.
Synthèse de l'évernine
Authors: Nicollier Gilles , Rebetez Michel , Tabacchi Raffaele , Gerlach Hans , Thalmann Adolf
Published: December 2004

Synthesis of Evernin

Two syntheses of the depside evernin 6 are described. Condensation of methyl acetoacetate and methyl crotonate followed by aromatization and reduction with Raney‐Ni led to methyl orsellinate (3). The condensation of everninic acid (4), obtained by partial methylation of 3 and saponification of the methyl ester, with methyl 2, 4‐dihydroxy‐3, 6‐dimethylbenzoate (methyl β‐orcin carboxylate) (5) in presence of cyclohexylcarbodiimide gave evernin (6). In a second syntheis methyl dihydroorsellinate (1) was regiospecifically converted into its 4‐methyl enol ether and aromatized via the benzene selenenyl derivative to yield methyl evernate (7). Benzylation followed by saponification gave the free acid 8. Methyl β‐orcin carboxylate (5) was synthesized in an analogous way from methyl 3,6‐dimethyl‐2,4‐dioxocyclohexanecarboxylate. Condensation of 8 with the methyl ester 5 by treatment with trifluoroacetic anhydride in toluene yielded 9, which could be converted into evernin (6) by hydrogenolysis of the benzyl ether.
Synthèse photochimique de biaryles et hétérobiaryles à partir d'aryl‐et hétéroarylamines, d'un nitrite d'alkyle et d'un substrat aromatique ou hétéroaromatique
Authors: Julliard Michel , Siv Chhan , Vernin Gaston , Metzger Jacques
Published: December 2004

Photochemical synthesis of biaryls and heterobiaryls from aryl and heteroarylamines, alkylnitrite and aromatic or heteromatic substrates

The photochemical reaction of aromatic and heteroaromatic amines with excess t‐butyl nitrite in aromatic solvents (benzene, p‐xylene, mesitylene) and in hetero‐aromatic solvents (furan, thiophene) leads to biaryls or heterobiaryls. t‐Butyl nitrite is more convenient than isopentyl nitrite which gives by‐products. This new method has been used to synthesize 28 compounds in 17 to 60% yield.
Etudes sur les composés organométalliques. XVII. Synthèse du tétracyclohexyltitane
Authors: Weber Jean‐Bernard , Porret Jacques , Jacot‐Guillarmod André
Published: December 2004

Studies of Organometallic Compounds. XVII Synthesis of Tetracyclohexyltitanium

Tetracyclohexyltitanium is prepared by reaction of TiCl4 or Ti(OC4H9)4 with dicyclohexylmagnesium in pentane or ether at ‐ 30°. Some aspects of its reactivity and its decomposition are described.
Etude sur les composés organométalliques. XVIII. Synthèse et caractérisation du μ‐oxo‐bis (dicyclopentadiènylméthyltitane IV)
Authors: Surer Hansruedi , Claude Saturnin , Jacot‐Guillarmod André
Published: December 2004

Studies of Organometallic Compounds. XVII: Synthesis and Caracterisation of μ‐oxo‐bis(dicyclopentadienylmethyltitane IV)

(Cp2TiCH3)2O is obtained by reacting (Cp2TiCl)2O with methyllithium. IR., NMR. and MS. spectrum are reported. Autocatalytic decomposition of the product is inferred from differential thermal analytic measurements.
Radical Ions in the Pentalene Series [1]. Part II. Dibenzo [b,f]pentalene and its 5, 10‐dimethyl derivative
Authors: Fürderer Peter , Gerson Fabian , Rabinovitz Mordecai , Willner Itamar
Published: December 2004

Proton hyperfine data have been determined for the radical anions and cations of dibenzo [b,f]pentalene (III) and its 5, 10‐dimethyl derivative (IV). The assignment of the coupling constants to pairs of equivalent protons follows from a simple MO model, the use of which enables one to reproduce satisfactorily the experimental values. The proton hyperfine data, aHμ

The meaning of aHμis aHC(x),HC(y),whereas only x and y are given in the particular cases.

, for the radical anion III⊖. correlate fairly well with the π‐charge populations ϵμ derived from 1H‐NMR. spectra for the carbon centres μ in the dianion III2⊖. The analogous correlation is less good in the case of the radical cation III⊕. and the dication III2⊕., presumably due to the rough approximations involved in the evaluation of the numbers ϵμ for the latter species. The coupling constants aH5,10 for III⊖. and III⊕. are very close to the corresponding values aH4,6 for the radical ions of 1,3,5‐tri‐t‐butylpentalene (II), in accord with the prediction of the MO model. A similarity is also found between the proton hyperfine data for III⊖. and those for the radical anions of structurally related 1,4‐diphenyl‐1,3‐butadiene (V). On the other hand, there are striking changes in the coupling constants of the analogous protons on passing from III⊖. to the radical anions of dibenzo [a,e] cyclooctene (VI) and [16] annulene (VII), as a consequence of raising the symmetry from C2h to D2h and D4h, respectively.
Beitrag zum Mechanismus der stossinduzierten Fragmentierungen von quaternären Stickstoffverbindungen. 2. Mitteilung über stossinduzierte Fragmentierungen von felddesorbierten Kationen
Authors: Fischer Matthias , Veith Hans‐Jürgen
Published: December 2004

Mechanistic studies on the collision‐induced fragmentations of quaternary ammonium ions

The collision‐induced fragmentation behaviour of field desorbed quarternary ammonium ions has been investigated. A main reaction of these ions is the cleavage of the NC bond accompanied by hydrogen rearrangement, i.e. alkane loss from the tetraalkyl substituted ammonium ions of the iodides 1, 2 and 3, respectively, Deuterium labelling indicates that the hydrogen transfer to the leaving group occurs to the extent of about 80% from the α‐position and about 20% from the other positions of an alkyl group. Pronounced heterolytic cleavage of the NC bond is observed in the benzyl substituted ammonium ion of 4. The β‐phenylethyl substituted ammonium ion of 5 shows a homobenzylic heterolysis, possibly yielding the phenonium ion j.
1,1‐Disilyl‐2‐Alkenes: Preparation and Some Synthetic Applications. Preliminary communication
Authors: Wetter Hansjürg
Published: December 2004

Allyl sulfides and a selenide are metallated and silylated with chloro (penta‐methyl)disilane. Treatment of the resulting disilanylmethyl sulfides 4 with trimethyloxonium tetrafluoroborate furnishes 1,1‐disilyl‐2‐alkenes 5 in good yields. Some synthetic possibilities of 5 are outlined.
Structural Studies of Crystalline Enamines
Authors: Brown Kevin L. , Damm Lorenz , Dunitz Jack D. , Eschenmoser Albert , Hobi Reinhard , Kratky Christoph
Published: December 2004

Crystal structure analyses of five crystalline enamines together with recently published structural data for two other enamines reveal varying degree of pyramidality at the enamine nitrogen atom. The pyramidality appears to be most pronounced in enamines from piperidine and morpholine, less so in enamines derived from prolinoid amines. A pyrolidine enamine obtained from a derivative of cyclohexane‐1,4‐dione seems to have a virtually planar enamine group. The implications of these findings for current stereochemical problems in enamine chemistry are discussed.
Natural Abundance 13C‐NMR. of Reduced Isoalloxazine
Authors: Van Schagen Cees G. , Müller Franz
Published: December 2004

When an isoalloxazine derivative (1) was reduced (2) its 13C‐NMR. resonances were all shifted upfield and the largest shifts were observed for C (4a), C(6) and C(8) but downfield shifts for C(2), C(4) and C(10a). The results and their biochemical implications are shortly discussed.
S‐Alkylation en série hétérocyclique par catalyse par transfert de phase: thioalkyl‐2‐thiazoles, thioalkyl‐2‐Δ‐4‐thiazolines et thioalkyl‐2‐benzothiazoles
Authors: Dou Henri J. M. , Hassanaly Parina , Kister Jacky , Vernin Gaston , Metzger Jacques
Published: December 2004

S‐Alkylation in heterocyclic serie by phase transfer catalysis: 2‐alkylthiothiazoles, 2‐alkylthio‐Δ‐4‐thiazolines and 2‐alkylthiobenzothiazoles

Some Δ‐4‐thiazoline‐, thiazolidine‐, and benzothiazoline‐2‐thiones have been S‐alkylated by phase transfer catalysis; yields averaged 80 to 90%. With halogenated heterocyclic compounds of poor reactivity, the main reaction consisted in a dequaternization of the catalyst by the thiones acting as nucleophiles.
Stoffwechselprodukte von Mikroorganismen. 177. Mitteilung. Avilamycin C
Authors: Heilman William , Kupfer Ernst , Keller‐Schierlein Walter , Zähner Hans , Wolf Heinz , Peter Heinrich H.
Published: December 2004

From cultures of the Avilamycin (Avilamycin A) producing organism, Streptomyces viridochromogenes, strain ETH 23575, a second antibiotic, Avilamycin C, C61H90Cl2O32 could be isolated in crystalline form. Both Avilamycins belong to the group of the Orthosomycins. By IR., 1H‐ and 13C‐NMR. spectroscopy and by transformation to a common derivative it could be proven that Avilamycin A is a methyl ketone, Avilamycin C the corresponding methyl carbinol.
Thermogravimetrische Untersuchung der reduzierenden Chlorierung von Tonerde
Authors: Müller Hans‐Peter , Baiker Alfons , Richarz Werner
Published: December 2004

Thermogravimetric analysis of the reducing chlorination of alumina

The kinetics of the chlorination of dehydrated alumina with (CO/Cl2) mixtures were studied in the temperature range of 400–900°. The temperature of dehydration of the alumina was shown to be critical for the reaction rates of the subsequent chlorination. Optimal reaction rates could be observed with equimolar (CO/Cl2) mixtures in the range of 600–700°. At higher temperatures, only a very small increase in reaction rates with increasing temperature could be observed which is thought to be due to the influence of gaseous diffusion gradients in the porous alumina and a progressive decrease in surface area. Granulometric as well as scanning electron microscope studies have shown that with progressing reaction the alumina particles become hollow while retaining their outer shape and size up to a high degree of conversion.
5α‐24‐Norcholestan‐3β‐ol and (24Z)‐Stigmasta‐5,7,24(28)‐trien‐3β‐ol, Two New Marine Sterols from the Pacific Sponges Terpios zeteki and Dysidea herbacea
Authors: Delseth Claude , Tolela Luhata , Djerassi Carl , Scheuer Paul J. , Wells Robert J.
Published: December 2004

The steroidal components of 2 marine sponges, Terpios zeteki (from Hawaii) and Dysidea herbacea (from Australia) were fractionated through a combination of chromatographic methods, including reversed phase HPLC., and were analyzed by a combination of physical methods, including high resolution GC.‐MS. and 360 MHz 1H‐NMR. T. zeteki contains 6 conventional 5α‐stanols which comprise 91% of the sterol mixture, and traces (0.5%) of a new C26 sterol, 5α‐24‐norcholestan‐3β‐ol. Minor amounts of conventional Δ5‐sterols (6.5%) and of a single Δ4‐3‐ketosteroid (1.5%) were also present. In contrast, the Australian sponge (D. herbacea) contains 3 Δ5,7‐sterols which comprise 1.5% of the sterol mixture, and one new C29 sterol, (24 Z)‐stigmasta‐5,7,24(28)‐trien‐3β‐ol, as the major component (75%). In addition, minor amounts of conventional 5α‐stanols (0.5%), Δ5‐sterols (5%) and 5α‐Δ7‐sterols (18%) were present in this complex sterol mixture. The possible dietary or endosymbiotic origins of these sterols are discussed.
Halochrome Molekeln. Synthese und acidobasisches Verhalten substituierter 3′,6′‐Bis (dimethylamino)‐spiro [5H‐imidazo [2, 1‐α]‐isoindolin‐5,9′‐xanthene]
Authors: Gunzenhauser Sigmund , Hellrung Bruno , Balli Heinz
Published: December 2004

Halochromic Molecules. Synthesis and Acidobasic Behaviour of Substituted 3′,6′‐Bis(dimethylamino)‐spiro [5H‐imidazo [2,1‐α]isoindolin‐5,9′‐xanthenes]

Substituted 3′,6′‐Bis (dimethylamino)‐spiro [5H‐imidazo [2, 1‐α]isoindolin‐5,9′‐xanthenes] are prepared and their 1H‐NMR. spectra are discussed. An investigation of the complex protonation equilibria is made by stopped flow kinetic and spectrophotometric methods. pK values are determined and the results are discussed.
Nucleophilic Addition to C, C Double Bonds. Proximity and homoconjugative effects. Preliminary communication
Authors: Pfund Rolland A. , Ganter Camille
Published: December 2004

Proximity effects alone as well as in combination with electronic effects are responsible for the observed phenomenon of base‐catalyzed ether formation initiated by nucleophilic attack on a C, C double bond of the tricyclic olefin alcohols 1–10 (Scheme 1, Table 1).

With compounds 1–4, bearing a keto group, formation of the ethers 11–14 proceeds through a corresponding homoenolate b (Scheme 2) as an intermediate. In one case such a species could be trapped as the methyl ether 21 (Scheme 3).

Special attention is given to the stereochemical course of the homoketonization. Ring opening in 21 under acidic conditions occurs regioselectively, however non‐stereoselectively (Scheme 3). Full regio‐ and stereoselectivity (retention) is observed under basic conditions starting from the unsaturated keto alcohols 1 and 2 (Scheme 4) as well as from the keto ethers 11 and 12 (Scheme 5, Table 2).
Zur Photochemie von 1, 2‐Benzisoxazolen in stark saurer Lösung
Authors: Doppler Thomas , Schmid Hans , Hansen Hans‐Jürgen
Published: December 2004

On the Photochemistry of 1, 2‐Benzisoxazoles in Strongly Acidic Solution

The 1, 2‐benzisoxazoles 1a, 1b and 1d when dissolved in 96% sulfuric acid and irradiated through a quartz filter with a mercury high‐presure lamp yield, after work‐up, mixtures of 2, 5‐ and 2, 3‐dihydroxy‐acylbenzenes (2 and 3, respectively; cf. Schemes 1 and 3 and Table 1). Irradiation of 3, 5‐dimethyl‐1, 2‐benzisoxazole (1c) in 96% sulfuric acid leads to the formation of 2, 3‐dihydroxy‐5‐methyl‐acetophenone (3c) in only 6% yield (cf. Table 1). It is assumed that the 1, 2‐benzisoxazolium ions react in the excited singlet state by heterolytic cleavage of the N, O‐bond to yield the corresponding aryl oxenium ions 7 in the singlet ground state (see Scheme 5). Reaction of 7 with HSO4⊖ ions, present in 96% sulfuric acid, yields, after hydrolysis, the dihydroxy compounds 2 and 3. Photolysis of 3‐methyl‐1, 2‐benzisoxazole (1b) in diluted sulfuric acid (0,5 to 9 M) in methanol or water leads only to the formation of 2‐amino‐phenol (6; see Scheme 3), presumable via photo‐isomerization of 1b to 2‐methylbenzoxazole (5b) which then is hydrolyzed to give 6.
Über die Herstellung des Methyl‐α‐D‐fructopyranosides und die Struktur der dabei gebildeten Orthoester
Authors: Steinlin Heinrich , Camarda Lorenzo , Vasella Andrea
Published: December 2004

Concerning the preparation of methyl α‐D‐fructopyranoside and the structure of the orthoester by‐products

Koenigs‐Knorr glycosidation (AgClO4/Ag2CO3) of the easily accessible p‐nitrobenzoylated fructosylchloride 7 yields mainly the protected glycoside 3 which was deacylated to the known title compound 1. The orthoesters 15 and 16 were formed as by‐products in this glycosidation whilst the analogous orthoesters 21 and 22 are formed as main products in the glycosidation (Ag2CO3) of the benzoylated fructosylchloride 12. The structure of these orthoesters was deduced mainly from their spectroscopic data, from those of their derivatives 17, 18, 19, 20, 25 and 26 and by comparison of the latter with the model compounds 31 and 34.
The Effect of Choleates on the Solubilization of Water in Water/AOT/Cyclohexane (W/O)‐Microemulsions
Authors: Eicke Hans‐Friedrich
Published: December 2004

Experimental investigations on the cosurfactant effect of alkali and tetraalkylammonium choleates in water/AOT/cyclohexane (W/O)‐microemulsions were carried out. The results prompted considerations on a thermodynamic and molecular level. The molecular view emphasizes the significance of hydration interactions between cosurfactant and solubilized water.
Papain‐induced Oligomerization of α‐Amino Acid Esters
Authors: Anderson Gregory , Luisi Pier Luigi
Published: December 2004

Oligomers of leucine, methionine, phenylalanine, and tyrosine were prepared enzymatically (using papain) from the respective methyl esters, with yields ranging from 51–96%. The effect of pH, buffer and salt concentration, and addition of alcohol on the oligomerization of leucine methyl ester was examined. The limits and potentialities of the enzymatic reaction as a method for obtaining monodisperse oligomers are discussed.
Synthese von 4(5)‐acyl‐5(4)‐alkylimidazolen aus symmetrischen 1,3‐dicarbonylverbindungen
Authors: Krebs Ernst‐Peter , Bondi Enrico
Published: December 2004

Synthesis of 4(5)‐Acyl‐5(4)‐alkylimidazoles from Symmetrical 1,3‐Diones

A new synthesis of 4(5)‐acyl‐5(4)‐alkylimidazoles 1 is described. The symmetrical 1,3‐diones 5a and 5b were reacted with N2O4 to give the nitro compounds 7a and 7b, respectively; 5c was treated with NaNO2 to give the nitroso compound 7c (Scheme 2). Hydrogenation of 7a, 7b and 7c over Pd/C in acetic acid/acetic formic anhydride yielded the formamides 9a, 9b and 9c, whose cyclization in formamide/formic acid afforded the 4(5)‐acyl‐5(4)‐alkylimidazoles 1a, 1b and 1c, respectively. Oxazoles 11a and 11b were obtained from the corresponding formamides 9a and 9b with methanesulfonic acid/P2O5.
Synthese von rac‐2‐Cyano‐1‐methyl‐3‐[2‐[(4,5,6,7‐tetrahydro‐4‐benzimidazolyl)thio]äthyl]guanidin; ein konformationell gehindertes Cimetidin‐Analogon
Authors: Krebs Ernst‐Peter
Published: December 2004

Synthesis of rac‐2‐Cyano‐1‐methyl‐3‐[2‐[(4,5,6,7‐tetrahydro‐4‐benzimidazolyl)thio]ethyl]guanidin, a Conformationally Restricted Cimetidine

Internationaler Freiname (‘generic name’) für 2‐Cyano‐1‐methyl‐3‐[2‐[(5‐methyl‐imidazol‐4‐yl)‐methylthio]äthyl]guanidin (2) [1].

Analogue

The physiological actions of histamine (1) are mediated by at least two classes of receptors. A short definition of histamine H1‐ and H2‐receptors is given. Cimetidine (2) is a known specific H2‐blocking agent. Compound 3 is a cimetidine analogue with a conformationally restricted side chain. The synthesis of 3 as well as some physicochemical and pharmacological data of 3 are described.