bluuebunny/crossref_metadata_2025 huggingface dataset:
Nucleophilic and Electrophilic Properties of Carbenes, II. 4‐Biphenylyl‐4‐pyridylcarbene
Authors: Lán Nguyňñ Mǒng , Wentrup Curt
Published: December 2004

Flash pyrolysis of 4‐biphenylyl‐4‐pyridyldiazomethane (4 gave 7‐phenyl‐2‐azafluorene)5, which was also synthesized from 3‐mesitoylpyridine in four steps. 4‐Biphenylyl‐4‐pyridyl‐[13C]‐diazomethane (9) was prepared from isonicotinic [13C]‐acid chloride in three steps. Flash pyrolysis of 9 established that 4a‐ and 4b‐[13C]‐7‐phenyl‐2‐azafluorenes are formed in a carbene‐carbene rearrangement in which ring expansion of the biphenyl part dominates over that of the pyridine ring. These results support the postulate that carbene‐carbene rearrangements are favoured by a nucleophilic interaction between the filled singlet carbene sp2 (σ) orbital and the lowest unoccupied molecular orbital (LUMO) of the aromatic ring.
Synthese eines 17β‐homologen 3β‐Hydroxy‐card‐5,22‐dienolids Partialsynthetische Versuche in der Reihe der Herzgifte, 8. Mitteilung
Authors: Güntert Theodor W. , Linde Horst H. A. , Ragab Mohamed S. , Spengel Sigrid
Published: December 2004

Synthesis of a homologous 3β‐hydroxycard‐5,22‐dienolide.

We describe the synthesis of 4′‐[(3β‐hydroxy‐androst‐5‐en‐17β‐yl)methyl]‐2′(5′)‐furanone (22) starting from 3β‐acetoxy‐androst‐5‐ene‐17β‐carboxylic acid (5).
A 300 MHz NMR. Evidence for the Configuration of Roxburghine B
Authors: Cistaro Carla , Mondelli Rosanna , Anteunis Marc
Published: December 2004

The 300 MHz1H‐NMR. spectrum of the alkaloid Roxburghine B is completely analysed. The coupling constant values give evidence for the configuration, which is revised toepi‐allo: H(3β), H(15α), H(20α) and C(18β).
Synthesis of 7‐Deamidocephalosporin Lactone. Preliminary Communication
Authors: Schmid Gérard , Prasad Kapa K. , Petrzilka Theodor
Published: December 2004

Condensation of azetidinone 1 with mercaptan 3 gave compound 5. Bromination of 5 afforded two isomeric bromohydrins 11a and 11b which differ in the configuration at C(4). Acetylation and reduction with zinc and acetic acid of the above bromohydrins gave 7‐deamidocephalosporin lactone (14).
Dewar Benzene and Some of its Derivatives. A photoelectron spectroscopic analysis [1]
Authors: Bieri Gerhard , Heilbronner Edgar , Kobayashi Tsunetoshi , Schmelzer Andreas , Goldstein Melvin J. , Leight Ronald S. , Lipton Mark S.
Published: December 2004

The near degeneracy of the two lowest ionization energies of Dewar benzene can be understood in terms of closely competitive ‘through‐bond’ and ‘through‐space’ interaction. Empirical, semiempirical, and open‐shell ab initio procedures converge to require mutually consistent symmetry assignments.
Transition‐Metal Complexes with Bidentate Ligands Spanning trans‐Positions. I. The synthesis of 2,11‐bis(diphenylphosphinomethyl)benzo[c]‐phenanthrene, a ligand promoting the formation of square planar complexes
Authors: DeStefano N. J. , Johnson D. K. , Lane R. M. , Venanzi L. M.
Published: December 2004

The bidentate ligand 2,11‐bis(diphenylphosphinomethyl)benzo[c]phenanthrene (1) was synthesized from 2,11‐dimethyl‐benzo[c]phenanthrene (3) via the corresponding bromomethyl derivative 9. 3 was obtained from the cyclization with boron trifluoride etherate of 1,1‐di‐(p‐methylphenethyl)‐epoxyethane (7), which was prepared from 1,5‐di(p‐tolyl)‐pentan‐3‐one (6).
Photocyclisierung von 1‐[3‐(Chloracetylamino)propyl]‐3‐methylindol. 12. Mitteilung über synthetische Indol‐Verbindungen
Authors: Schindler Othmar , Niklaus Peter , Stauss Urs , Härter Hans Peter
Published: December 2004

Photochemical cyclization of 1‐[3‐(chloroacetylamino)propyl]‐3‐methyl‐indole.

Photochemical cyclization of 1‐[3‐(chloroacetylamino)propyl]‐3‐methyl‐indole involving loss of HCl leads to the three isomers 2, 3 and 4, the structures of which have been determined by physical and chemical methods.
13C‐NMR. Spectroscopy of Naturally Occuring Substances. XLII. Conformational analysis of quebrachamine‐like indole alkaloids and related substances
Authors: Wenkert Ernest , Hagaman Edward W. , Kunesch Nicole , Wang Nai‐yi , Zsadon Béla
Published: December 2004

The 13C shifts of 16α‐ and 16β‐substituted derivatives of quebrachamine, 14,15‐dehydroquebrachamine, cleavamine, 15,20α‐dihydrocleavamine and 15,20β‐dihydrocleavamine are determined and correlated with possible conformations of these tetracycles. The method of analysis of the C(16) configuration of these compounds, which emanated from this study, is used for the determination of the configuration of the site of coupling of vindoline and cleavamine β‐chloroindolenine.
Synthesis with 1,2‐Oxazines. II. Synthesis and Properties of 2,3‐dimethyl‐5,6‐dihydro‐4H‐1,2‐oxaziniumiodide
Authors: Hardegger Bruno , Shatzmiller Shimon
Published: December 2004

Preparation of 2,3‐Dimethyl‐5,6‐dihydro‐4H‐1,2‐oxaziniumiodide was achieved by N‐alkylation of 3‐methyl‐5,6‐dihydro‐4H‐1,2‐oxazine. Reactions with C‐nucleophiles led to the corresponding N‐methyl‐perhydro‐1,2‐oxazine derivatives. Reaction with sodium hydride in triglyme led to 3‐methyl‐4‐aza‐1,3‐pentadiene.
«Alkaloide» in tierischem und menschlichem Gewebe. 6. Mitteilung [1] [2]. Synthese und absolute Konfiguration chiraler 2, 3, 10, 11 ‐ Tetrahydroxy‐8‐methyl‐berbine [3]
Authors: Bruderer Hans , Metzger Jean , Brossi Arnold , Daly John J.
Published: December 2004

Synthesis and absolute configuration of chiral 2, 3, 10, 11‐tetrahydroxy‐8‐methylberbines [3].

The synthesis and absolute configuration of the four optically active berbines Xa, b and XIa, b are described. These compounds consitute potential ‘alkaloids’ obtained by condensation of either R‐(+) or S‐(−)‐norlaudanosoline (THP, III) with acetaldehyde, a major metabolite of ethanol.
Aspects of Cyclization Reactions of 2,2′‐Diaminoazobenzene and 1,2‐Bis(2‐aminophenylazo)benzene macrocyclic Aza compounds, II
Authors: Skrabal Peter , Hohl‐Blumer Magadalena
Published: December 2004

Cyclization of diamine 5 with phthalaldehyde and of diamine 6 with glyoxal results in formation of the macrocyclic amino alcohol 8 and the rearrangement product 16, respectively. The properties and stability of 8 and the reactions of 6 with other bifunctional molecules are discussed.
Heterotricyclodecane XXI 2‐Aza‐7‐thia‐twistane (bzw. 2‐Thia‐7‐aza‐twistane)
Authors: Szczepanski Henry , Ganter Camille
Published: December 2004

2‐Aza‐7‐thia‐twistanes (or 2‐thia‐7‐aza‐twistanes, respectively)

The suitably substituted 9‐thiabicylo[3.3.1]nonanes 7–9 and 17 were synthesized and subsequently cyclized to the 2‐aza‐7‐thia‐twistanes 21–23 and 19, respectivelly, from which several other twistane derivatives (20 and 24–29) were prepared.
Réactions d'addition‐élmination à partir d'hétérocycles germaniés du type . III. Cas des diéthyl‐2,2‐germa‐2‐oxazolidines‐1,3 (R = et; X = O; Y = NH, NMe)
Authors: Dousse Gabriel , Lavayssière Hélène , Satgé Jacques
Published: December 2004

Addition‐elimination reactions from germanium heterocycles . III. 2,2‐Diethyl‐2‐germa‐1,‐3‐oxazolidines (R = Et; X = O; Y = NH, NMe).

The reactions of 2,2‐diethyl‐2‐germa‐1,3‐oxazolidines with heterocumulenes (PhNCO, PhNCS, CS2, CO2, CH2CO) and carbonyl compounds (aldehydes and ketones) are studied. Generally, monoinsertion derivatives are formed by addition of one molecule of the unsaturated compound accross the GeN bond. This bond is always the most reactive center of the molecule. In the case of the carbonyl compounds used, diinsertion may occur in a second step by a further addition across a GeO bond. Generally, this latter reaction is reversible. By thermal eliminat on of (Et2GeO)n or (Et2GeS)3 the monoaddition derivatives yield the corresponding oxazolidines and thiooxazolidines. The mechanisms of these reactions are discussed.
Neue, ungewöhnlich verlaufende Arylierungen der 1,5‐Dihydroxy‐4,8‐diaminoanthrachinon‐2,6‐disulfonsäure mit Kresolen
Authors: Adam Jean‐Marie , Hindermann Peter , Winkler Tammo
Published: December 2004

A novel course of a phenylation reaction of 1,5‐dihydroxy‐4,8‐diaminoanthraquin‐one‐2,6‐disulfonic acid with cresols.

The arylation of 1,5‐dihydroxy‐4,8‐diaminoanthraquinone‐2,6‐disulfonic acid with m‐cresol in conc. sulfuric acid gives in the presence of boric acid a mixture of monosulfonic acids which differ in the substitution of the m‐cresol moiety. The main product (8, 95%) is substituted at the p‐position to the methyl group, the side product (12, 5%) at the p‐position to the OH group. The monosulfonic acid 8, which could not be isolated is further sulfonated under the reaction conditions to the disulfonic acid 9. In the case of o‐cresol, the cresol moiety is substituted in the p‐position (16) to OH group and in the case of p‐cresol in the o‐position (20) to OH group. The obtained monosulfonic acids 16 and 20 resp. are partially sulfonated further under the reaction conditions. The new structures are elucidated by 1H‐ and 13C‐NMR. spectroscopy and the pattern of arylation reaction with phenol is discussed.
Lokalisierung der Ketogruppe in Inandenin‐onen. 160. Mitteilung über Alkaloide
Authors: Guggisberg Armin , Veith Hans‐Jürgen , Hesse Manfred , Schmid Hans
Published: December 2004

Localization of the keto group in Inandenin‐ones.

By Schmidt degradation of the spermidine alkaloids inandenine‐12‐on (1) and inandenine‐13‐on (2) from Oncinotis inandensis followed by hydrolysis, acetylation and esterification four different types of products were obtained: the dicarboxylic diesters 9 and 10, the ω‐amino‐carboxylic esters 11 and 12, the acetylated polyamines 14 and 15, and the acetylated triaminecarboxylic esters 16 and 17. By GLC. and mass spectral analysis of these degradation products, and by comparison with synthetic compounds it was possible to confirm the structures 1 and 2. The same alkaloid mixture (1+2) was obtained from the leaves of Oncinotis nitida BENTH.
Cryptates XXIV: Structure and stability of mononuclear and binuclear cation inclusion complexes of cylindrical macrotricyclic ligands
Authors: Lehn Jean‐Marie , Simon Jacques
Published: December 2004

The cylindrical macrotricyclic ligands 1–3 yield inclusion complexes, [3]‐cryptates, with various metal cations. NMR. studies indicate the successive formation of a mononuclear and a binuclear complex. The former is probably unsymmetrical undergoing fast intramolecular cation exchange; the latter is symmetrical, with a cation located on each macrocyclic subunit of the macrotricyclic system. A heteronuclear (Ag2+, Pb2+) complex has been observed. The stability constants of the mononuclear and binuclear alkali and alkaline‐earth cation complexes of ligands 1–3 have been determined by potentiometric methods. The stabilities are comparable to those of the complexes of the isolated macrocyclic subunit 5b. The binuclear complexes are almost as stable as the mononuclear one even in highly charged species like for instance the complex of ligand 2 with two barium cations. Cylindrical macrotricyclic ligands are topologically well suited for the designed positioning of two metal cations in a binuclear inclusion complex.
Über Pterinchemie. 58. Mitteilung [1]. Sterische Eigenschaften von acylierten 5,6,7,8‐Tetrahydropterinen. Rotameren von 5‐Trifluoracetyl‐tetrahydropterin‐Derivaten
Authors: Weber Rudolf , Viscontini Max
Published: December 2004

Sterochemical Properties of the Acylated 5,6,7,8‐Tetrahydropterines. Rotameres of the 5‐Trifluoroacetyl‐tetrahydropterine Derivatives

6‐Methyl‐ and 6,7‐dimethyl‐5,6,7,8‐tetrahydropterine are acylated with the anhydrides of acetic acid and trifluoroacetic acid. It is shown that the reactivity of the nitrogen otoms increases in the following order: N(3), N(8), N(2′) and N(5). Two rotameres are present in the 1H‐NMR. spectra of the N(5)‐trifluoroacetates, but not in those of the N(5)‐acetates.
Über Pterinchemie. 59. Mitteilung [1]. Konformationsanalyse von acylierten 5,6,7,8‐Tetrahydropterinen
Authors: Weber Rudolf , Viscontini Max
Published: December 2004

Conformational Analysis of Acylated 5,6,7,8‐Tetrahydropterines

The conformation of N(5)‐acetates, and of N(5)‐ and N(8)‐trifluoroacetates, respectively, of 6‐methyl‐ and cis‐6, 7‐dimethyl‐tetrahydropterines is studied by 1H‐NMR. spectroscopy. It is shown that the methyl group next to the acylated nitrogen atom is in quasi‐axial position.
Gasförmige Komplexe zwischen Kobaltchlorid und Indiumchlorid
Authors: Dienstbach Falko , Emmenegger Franzpeter
Published: December 2004

Gaseous Complexes between Cobaltchloride and Indiumchloride

The equilibria (1) and (2):

were investigated by optical spectroscopy and by vapour pressure measurements using the transpiration method:

Together with thermodynamic data from the literature the results obtained allow a complete description of all heterogeneous solid/gas as well as the homogeneous equilibria in the gas phase of the system CoCl2/InCl3 in the temperature range 500–800°.
Réactions chimiques oscillantes (type Belousov‐Zhabotinskii) impliquant des cétones cycliques et aliphatiques
Authors: Farage Vincent J. , Stroot Philippe , Janjic Désimir
Published: December 2004

Oscillating Chemical Reactions (Belousov‐Zhabotinskii type) involving cyclic and aliphatic Ketones

Four ketonic compounds (cyclohexanone, cyclopentanone, butanone, and 3‐pentanone) have been found to generate chemical oscillations in the BrO3−/Ce4+/ketone system. The effect of changes in concentrations of the reagents has been investigated and differences in behaviour with other systems found. The dependence of these reactions on temperature has been studied and activation energies calculated.
Etudes photochimiques en série hétérocyclique. V. Mise en évidence d'oxazoles par photooxydation de thiazoles
Authors: Vernin Gaston , Treppendahl Svend , Metzger Jacques
Published: December 2004

Formation of oxazoles as by‐products of photooxydation of thiazoles

In the presence of air, light (high pressure mercury lamp) and iodine as sensitizer, benzene solution of arylthiazoles 2, 3 and 13 (see scheme 1) were converted into a mixture of photoisomers and aryloxazoles (see scheme 2).

Upon shorter times of irradiation under oxygen in chloroform containing methylene blue as a sensitizer 2,4,5‐triphenylthiazole (7) is converted in 2,4,5‐triphenyloxazole.

Under usual photooxidation conditions, in methanol as solvent, most of arylthiazoles studied gave a mixture of nitriles, amides, acids esters and diketones. In the case of thiazole 7, the corresponding oxazole was also found.

A possible mechanism for the photochemical oxidation of arylthiazoles to aryloxazoles, via 2,5‐ and 4,5‐endo‐peroxides, may be proposed (see schemes 5 and 6).
Das unterschiedliche massenspektrometrische Fragmentierungsverhalten von Lysinmethylester und dessen N,N′‐Diacetylderivat. 27. Mitteilung über das massenspektrometrische Verhalten von Stickstoffverbindungen
Authors: Roessler Felix , Hesse Manfred
Published: December 2004

The Different Behaviour of Lysine Methyl Ester and its N,N′‐Diacetyl Derivative under Electron Impact

The base peak in the spectrum of lysine methyl ester is due to the fragment ion C5H10N (m/e 84), for which the cyclic structure g (Scheme 1) is deduced. During its formation from the [M‐COOCH3]‐ion an equilibration of both nitrogen atoms takes place (ion c, Scheme 1). The cyclic nature of ion m/e 84 is in agreement with the intensity of the corresponding ions in the spectra of homologues of lysine methyl ester (Fig. 1). Although in comparison with lysine methyl ester (1) N,N′‐diacetyl‐lysine methyl ester (7) shows the same general fragmentation pathway with formation of the ions [M‐COOCH3] and [M‐COOCH3‐H2NCOCH3] (m/e 126), the exact fragmentation mechanism proves to the different. Two mechanisms are discussed for the formation of the ion m/e 126 from 7 (Schemes 2 and 3). The results are based on the spectra of labelled derivatives.
Synthese und Umwandlungen von Isoxazolidin‐Nucleosiden
Authors: Vasella Andrea
Published: December 2004

Synthesis and Transformations of Isoxazolidine‐Nucleosides

Reaction of the oxime 12 with formaldehyde, acetaldehyde or acetone in the presence of methacrylic acid methylester leads in a highly stereoselective 1,3 dipolar cycloaddition of the corresponding nitrones to the protected isoxazolidine ribosides 13, 14, 20, 21 and 26 (Scheme 1 and 2).

Using a new, mild procedure to effect detriylation, the cycloaddition products were transformed into the alcohols 16–19, 22–25 and 27.

Cleavage of a mixture of the glycosides 16 and 17 yielded the N‐unsubstituted isoxazolidine 29 in 65% optical purity while the cleavage of 27 gave optically pure 28.

Alternatively, the isoxazolidine ribosides 13, 14, 16–18 and 26 were transformed via reductive cleavage of the isoxazolidine N‐O bond and subsequent lactamization into the corresponding pyrrolidinone‐ribosides 30, 33, 35, 42, 49 and 50, the ribitolyl pyrrolidinones 31, 34, 36–39 and 43–46 (see Scheme 4) and the ribitolyl isoxazolidine 47.
Notiz über Methoden zur Umwandlung von 1,2‐Dicarbonsäuren in konjugiert ungesättigte Monocarbonsäuren. Über synthetische Methoden, 12.Mitteilung
Authors: Gygax Peter , Eschenmoser Albert
Published: December 2004

A Note on Methods for the Transformation of 1,2‐Dicarboxylic Acids into α, β‐Unsaturated Monocarboxylic Acids.

A model study using the Diels‐Alder adduct of maleic anhydride and butadiene (see scheme 3) exemplifies the conversion of the succinic acid type of structure into α, β‐unsaturated carboxylic acids via two complementary fragmentations of 3,6‐dioxo‐perhydro‐1,2‐oxazine derivatives.
Asymmetric Hydroformylation of α‐[2H]‐Styrene. Preliminary Communication
Authors: Stefani Annibale , Tatone Dante
Published: December 2004

The hydroformylation of α‐[2H]‐styrene in the presence of an asymmetric rhodium‐catalyst afforded two optically active isomeric aldehydes. The origin of the asymmetric induction is discussed on the basis of the chirality and the optical purity of the two products.
Exo‐ und endo‐Tricarbonyleisenkomplexe von bicyclischen 2,3‐Dimethylidenverbindungen
Authors: Steiner Ulrich , Hansen Hans‐Jürgen , Bachmann Kurt , Von Philipsborn Wolfgang
Published: December 2004

Exo‐ and endo‐Tricarbonyliron Complexes of Bicyclic 2,3‐Dimethylidene Compounds.

The preparation of exo‐ and endo‐tricarbonyliron complexes (exo‐ and endo‐5, ‐6, ‐8, and 9) of 2,3‐dimethylidene‐5‐bicyclo[2.2.1]heptene(1), ‐bicyclo[2.2.1]‐heptane (2), ‐5‐bicyclo[2.2.2]octene (3) and ‐bicyclo[2.2.2]octane (4) is described. The complexes are obtained by thermal reaction of the bicyclic butadienes with di‐ironenneacarbonyl in hexane solution. exo‐ and endo‐5 are also formed photochemically from ironpentacarbonyl and 1 in pentane solution at −35°. The structural assignment of exo‐ and endo‐5 and ‐6 is based on their mass‐spectra and on coordination shifts in 1H‐ and 13C‐NMR.‐spectra exo‐ and endo‐6 are correlated with exo‐ and endo‐5, respectively, by hydrogenation. Hydrogenation of the uncomplexed double bond in exo‐ and endo‐5 occurs in both complexes from the exo side as shown by deuteration experiments. The free ligand 1 reacts in the same stereospecific manner.
Dysidin, ein neuartiger, chlorhaltiger Naturstoff aus dem Schwamm Dysidea herbacea
Authors: Hofheinz Werner , Oberhänsli Willi E.
Published: December 2004

Dysidin, a novel chlorine containing natural product from the sponge Dysidea herbacea

Dysidin (1) has been isolated from the marine sponge Dysidea herbacea. It structure has been determined by degradation studies and spectroscopic methods. The synthesis of a degradation product is described. The relative and absolute configuration is established by X‐ray diffraction methods.
Zur Regioselektivität von Cycloadditionen photochemisch erzeugter Benzonitril‐isopropylide. 51. Mitteilung über Photoreaktionen
Authors: Gerber Ulrich , Heimgartner Heinz , Schmid Hans , Heinzelmann Willy
Published: December 2004

On the regioselectivity of cycloaddition reactions of photochemically generated benzonitrile‐isopropylides

This paper deals with the physical and chemical differences of zwitterionic benzo‐nitrile‐isopropylides, which differ by a p‐substituent in the phenyl ring (H, F, OCH3; Scheme 2). These dipolar species (4–6) are produced by irradiation of the corresponding 2 H‐azirines (1–3; Scheme 1) in a 2‐methylpentane glass at −185°. Their UV. spectra are reproduced in the Figure. The spectra of 4 and 5 are characterized by an ‘aromatic band’ at short wavelength, and a longer wavelength band at approximately 275 nm, which is considered to be characteristic of the nitrile‐ylide system. The UV. spectrum of the methoxy derivative 6, which shows a broad absorption at 260 nm, arises by an addition of the ‘nitrile‐ylide band’ and the anisole band. The three dipolar species 4–6 do not show any significant differences in the regioselectivity of the cycloaddition with methyl α‐methacrylate even though F and OCH3 have quite different σ‐constants (Scheme 1). The addition according to modus A is very much preferred (B/A = 0,076). – It seems, that the substituents F and OCH3 do not affect the physical and chemical behaviour of the parent benzonitrile‐isopropylide (4). All three dipolar species 4–6 react regiospecifically according to modus A with methyl trifluoroacetate (Scheme 1). The regioselectivity is reduced in the cycloaddition of 4 with methyl propiolate and ethyl phenylpropiolate (B/A = 0,04 and 0,28, respectively). The reduced regioselectivity in the latter case may be attributed to a reduced polarity of the triple bond in the dipolarophile.
Metallkomplexe von N‐substituierten 3‐Imino‐isoindolinonen
Authors: L'Eplattenier François A. , Frey Christoph , Rihs Greti
Published: December 2004

Metal Complexes of N‐substituted 3‐Imino‐isoindolinones

The condensation of 3‐imino‐isoindolinone 4 and benzimidazoles or benzthiazoles containing activated methyl‐, methylen‐ or aminogroups (5 resp. 6), yields the iso‐indolinone‐ligands 1 and 2. Metal ions such as Co2+, Ni2+, Cu2+ and Zn2+ form (1:2)‐complexes with these ligands of very high chemical and photochemical stabilities. The magnetic properties of these complexes indicate that the geometry around the central atoms is distorted tetrahedral. A X‐ray diffraction study of one of the Co(II)‐complexes confirms these findings.
Metal ion exchange in square planar Nickel and Palladium Mercaptoethylamine Complexes
Authors: Reichert R. , Schläpfer C. W.
Published: December 2004

Austauschversuche mit radioaktivem Nickel zeigen, dass Ni2+ und Pd2+ in Mercaptoäthylamin(MEA‐)‐Komplexen austauschbar sind. Aus UV./VIS.‐ und 1H‐NMR.‐spektroskopischen Daten geht hervor, dass die Anordnung der Metallionen in Ni2Pd(MEA)4Cl2 symmetrisch ist (Ni Pd Ni), in NiPd2(MEA)4Cl2 dagegen asymmetrisch (Ni Pd Pd).
D(−)‐ and L(+)‐γ‐Carboxyglutamic Acid (Gla): Resolution of Synthetic Gla Derivatives
Authors: Märki Walter , Oppliger Max , Thanei Peter , Schwyzer Robert
Published: December 2004

The chemical resolution of γ,γ′‐di‐t‐butyl DL‐N‐benzyloxycarbonyl‐γ‐carboxy‐glutamate is described in detail (preliminary account see [1]). The D (−)‐derivative was obtained as a crystalline quinine salt, and the L (+)‐derivative as a crystalline salt with (−)‐ephedrine in yields of 44 and 70%, respectively. Physical data are indicated for the enantiomers of γ,γ′‐di‐t‐butyl N‐benzyloxycarbonyl‐γ‐carboxyglutamate, γ,γ′‐di‐t‐butyl γ‐carboxyglutamate, and γ‐carboxyglutamic acid. The absolute configurations and optical purities of the γ,γ′‐di‐t‐butyl (+)‐ and (−)‐N‐benzyloxycarbonyl‐γ‐carboxyglutamates were determined by removal of the protecting groups and decarboxylation to optically active glutamic acid.
Azimine. II. Synthese und thermische Fragmentierung von cis‐ und trans‐2,3‐Diphenyl‐1‐phthalimido‐2,3‐di[15N]‐azimin
Authors: Leuenberger Christian , Karpf Martin , Hoesch Lienhard , Dreiding André S.
Published: December 2004

Azimines. II

Teil I, siehe [1].

.
Preparation and Thermal Fragmentation of cis‐ and trans‐2,3‐Diphenyl‐1‐phthalimido‐2,3‐di[15N]‐azimine

Teilweise vorgetragen in der Versammlung der Schweizerischen Chemischen Gesellschaft am 8./9. Oktober 1976 in Genf und als Autoreferat veröffentlicht [2].

cis‐ and trans‐2,3‐Diphenyl‐1‐phthalimido‐2,3‐di[15N]‐azimine (11 and 12) wer synthesized from cis‐di[15N]‐azobenzene (10) and phthalimido‐nitrene (2), the latter generated by lead tetraacetate oxidation of N‐aminophthalimide (1). Useful information was obtained from the comparison of several data of 11 and 12 with those of the unmarked diphenyl‐azimines 5 and 6 (R = C6H5).

The 15N‐ and 13C‐NMR. spectra of 11 and 12 were interpreted to furnish additional evidence for the azimine structure and for the indicated configurations. The IR. spectra permitted identification of two bands in the 1200 to 1450 cm−1 region, probably characteristic for the functionality of diaryl‐phthalimido‐azimines. Comparison of the mass spectrum of 11/12 with that of the unmarked analogues 5/6 (R = C6H5) permitted the interpretation of the fragmentation path of 1‐phthalimidoazimines. The major path may be the purely thermal decomposition to 13 and 7 (R = C6H5), respectively. Two other competing fragmentation paths are discussed.

Prolonged thermolysis of 11 at 61° in solution gave 83% of N,N′‐diphenyl‐N N′‐phthaloyl‐di[15N]‐hydrazine (13) of 98% isotope purity, which means that the imide nitrogen atom and N(1) of the azimine function are removed in this reaction. A mechanism passing through an intermediate cyclic tetrazene 16 is considered.

Benzocyclobutenedione (14) added to trans‐azobenzene (4, R = C6H5) under the influence of a high pressure lamp in a quarz apparatus to give N,N′‐diphenyl‐N,N′‐phthaloyl‐hydrazine (7, R = C6H5). This reaction was found not to take place in the dark, even after prolonged heating in trichloromethane.
Photochemistry of Chlorinated 2‐Cycloalkenones
Authors: Altmeyer Isabelle , Margaretha Paul
Published: December 2004

The 6‐chloro‐2‐cyclohexenones 3, 6 and 11, and the 5‐chloro‐2‐cyclopentenone 15 were newly synthesized. The results obtained with compounds 3 and 15 in photocycloadditions to olefins show that the oxetane vs. cyclobutane product ratio is reduced by the substitution of florine by chlorine in the α′ ‐position of the enone. No oxetanes are formed in the intramolecular photocycloaddition of 6. Compound 11 does not photoadd to olefins. The newly synthesized 2‐chloro‐3‐cyclohexenones 8 and 9 are also photostable towards light of λ=366 nm, but π‐π*‐excitation (λ=254 nm) in pentane leads to the formation of 4,4‐dimethylcyclohexanone (29).
Isolation and Identification of Three Major Metabolites of Retinoic Acid from Rat Feces
Authors: Hänni Ralph , Bigler Felix
Published: December 2004

Following the intraperitoneal administration of high doses of 14C‐ and 3H‐ labelled retinoic acid (1) to rats, three major metabolites and the intact compound were isolated from the feces in microgram amounts by use of column, thin‐layer and high‐pressure liquid chromatography. Their structures were elucidated by mass spectrometry and Fourier Transform 1H‐NMR. spectroscopy as 2 (all‐trans‐4‐oxoretinoic acid), 3 (7‐trans‐9‐cis‐11‐trans‐13‐trans‐5′‐hydroxy‐retinoic acid).

Hydroxylation of the 5‐methyl group of the cyclohexene ring, oxidation of the cyclohexene ring in position 4 and cis‐trans isomerisation of the nonatetraenoic acid side chain were the reactions, which produced these products from retinoic acid. The metabolites 2 and 4 each accounted for about 4% of the radioactivity administered. The metabolite 3 and the parent compound accounted for about 16% and 17% of the dose, respectively.
Nouveaux exemples de radicaux libres stables de dérivés hétérocycliques de sucres. Communication préliminaire
Authors: Tronchet Jean M. J. , Ojha‐Poncet Joëlle , Winter‐Mihaly Eva , Kohler Boris , Geoffroy Michel
Published: December 2004

Some more examples of stable free radicals of carbohydrate heterocyclic derivatives

2‐Glycosyl‐4,4,5,5‐tetramethylimidazoline‐ 3‐oxide‐1‐oxyls and 2‐glycosyl‐4,4,5,5‐tetramethylimidazoline 1‐oxyls have been prepared in nine carbohydrate series, which proves the generality of the method. The hyperfine coupling constant between the free electron and the α‐proton of the glycosyl group is never very large (0‐2.3 G) but a correlation between its value and the structure of the aglycone has been noted. Free radicals of that type, stable in aqueous solutions, are potentially interesting for biological studies.
Hormone‐Receptor Interactions. Carboranylalanine (Car) as a Phenylalanine Analogue: Reactions with Chymotrypsin
Authors: Fischli Walter , Leukart Othmar , Schwyzer Robert
Published: December 2004

In order to test the effects of the replacement of phenylalanine by carboranylalanine (Car) in biological ligand‐acceptor interactions, Z · Ala‐Ala‐Car · OH (1) and Ac · Car · OEt (2) were synthesized and their reactions with chymotrypsin studied. The two compounds proved to be good inhibitors with K(i) values of 3 · 10−4M (1) and 8.6 · 104M (2); the K(i) of Z · Ala‐Ala‐Phe · OH (1a) is 1 · 10−3M. The inhibition constants were determined by a new photolytic technique, inhibition of photoaffinity labelling by Z · Ala‐Ala‐Phe(pN3) · OH. Ac · Car · OEt is not hydrolysed by chymotrypsin. The findings indicate that the carboranyl group can interact with the ‘phenyl recognition site’ of the enzyme to produce the binding that is characteristic of aromatic amino acid residues. However, some kind of distortion in the region of the ‘mechanistic site’ must be postulated in order to account for the failure of hydrolysis. Some possible effects of the replacement of aromatic amino acids by Car in peptide hormones on hormone‐receptor interactions are discussed.
Synthesis of 4‐(4′‐Methyl‐2′‐oxo‐cyclohex‐3′‐en‐1′‐yl)‐pentanal and its Conversion into Derivatives of Spiro[4.5]decane and of 1,6,7,7a‐Tetrahydro‐2H‐indene
Authors: Goldberg Ora , Dreiding André S.
Published: December 2004

Synthese von 4‐(4′‐Methyl‐2′‐oxo‐cyclohex‐3′‐en‐1′‐yl)‐pentanal und dessen Umwandlung in Spiro[4.5]decan‐ und 1,6,7,7a‐Tetrahydro‐2H‐inden‐Derivate

Es wird die Synthese von 4‐(4′‐Methyl‐2′‐oxo‐cyclohex‐3′‐en‐1′‐yl)‐pentanal als ein (1:1)‐Gemisch von zwei Diastereoisomeren 10A und 10B auf folgendem Weg beschrieben: Die Umsetzung des Grignard‐Reagens von 1,1‐Äthylendioxy‐3‐brom‐propan (2) mit 2‐Methoxy‐4‐methyl‐acetophenon (1) ergab 1,1‐Äthylendioxy‐4‐hydroxy‐4‐(2′‐methoxy‐4′‐methyl‐phenyl)‐pentan (3), welches sich mit methanolischer Salzsäure in 2‐Methoxy‐5‐(2′‐methoxy‐4′‐methyl‐phenyl)‐5‐methyl‐tetrahydrofuran (7A,B) umwandeln liess. Durch Birch‐Reduktion von 7A,B wurde 4‐(2′‐Methoxy‐4′‐methyl‐cyclohexa‐1′,4′‐dien‐1′‐yl)‐pentan‐1‐ol (8), und danach durch milde Hydrolyse 4‐(4′‐Methyl‐2′‐oxo‐cyclohex‐3′‐en‐1′‐yl)‐pentan‐1‐ol (9A,B)2 erhalten. Oxydation von 9A,B lieferte schliesslich den erwähnten Keto‐aldehyd 10A,B. Einige Produkte von Nebenreaktionen, nämlich 4, 5, 11, 12 und 13A,B, sind auch beschrieben.

Der Keto‐aldehyd 10A,B liess sich in ein Gemisch, bestehend aus drei Diastereo‐isomeren A, B und C von 1‐Hydroxy‐4,8‐dimethyl‐spiro[4.5] dec‐7‐en‐6‐on (15) und aus zwei Diastereoisomeren A und B von 1,5‐Dimethyl‐1,6,7,7a‐tetrahydro‐2H‐inden‐3‐carbaldehyd (14), umwandeln. Für diese aldolartigen Cyclisierungen wurden vier verschiedene Methoden verwendet: (a) Stehenlassen in Tetrachlorkohlenstoff‐lösung, (b) Behandlung mit etwas Trifluoressigsäure in Chloroformlösung, (c) und (d) Schütteln einer Ätherlösung mit wässeriger Salzsäure oder Natronlauge. Oxydation von 15A und 15C lieferte eines der Diasteroisomeren von 4,8‐Dimethyl‐spiro[4.5]‐dec‐7‐en‐1,6‐dion (16A), und Oxydation von 15B führte zum anderen (16B).
1,3‐Cyclobutandionderivate aus Keten
Authors: Tenud Leander , Weilenmann Max , Dallwigk Edgar
Published: December 2004

1,3‐Cyclobutanedione derivatives from ketene

The dimerisation of ketene leads mainly to the methylidene‐β‐lactone ‘Diketene’ 2c. It is shown, that also a small amount of the symmetrical dimer, 1,3‐cyclobutadione 1c is produced, which under the reaction conditions is acetylated to 3‐acetoxycyclo‐butenone (5).
Synthese von Benzofulvenen und Dibenzofulvenen über 1‐Chloralkyl‐acetate
Authors: Neuenschwander Markus , Vögeli Rudolf , Fahrni Hans‐Peter , Lehmann Hans , Ruder Jean‐Pierre
Published: December 2004

Synthesis of benzofulvenes and dibenzofulvenes via 1‐chloroalkyl‐acetates

1,2‐Benzofulvene (6a) and 1,2,3,4‐dibenzofulvene (7a) as well as the corresponding 6‐methyl‐ and 6‐phenyl‐derivatives are prepared by reaction of sodium indenide and sodium fluorenide with 1‐chloroalkyl acetates (3), followed by elimination with KOC(CH3)3. The over‐all yields are comparable with the results of the fulvene series and are in most cases considerably higher than the yields of the Thiele‐method.
Thermische und photochemisch induzierte intramolekulare, 1,3‐dipolare Cycloadditionen von 4‐Phenyl‐3‐(2‐allylphenyl)‐sydnon. Vorläufige Mitteilung. 53. Mitteilung über Photoreaktionen
Authors: Meier Hansruedi , Heimgartner Heinz , Schmid Hans
Published: December 2004

Thermal and photochemically induced intramolecular 1,3‐dipolar cycloaddition reactions of 4‐phenyl‐3‐(2‐allylphenyl)‐sydnone

The title compound 9 was synthesised in the usual way, starting from 2‐allylaniline and ethyl 2‐bromo‐2‐phenylacetate, via the nitrosaminacid 8 (Scheme 2). 9 reacts at room temperature with its potential azomethinimine‐function in an intramolecular [3+2]‐cycloaddition to give the tricyclic compound 11 (Scheme 2). On irradiation, 9 yields the dihydro‐3H‐pyrazolo[2,3‐a]indole 10 which probably arises by intramolecular [3+2]‐cycloaddition of the corresponding intermediate nitrilimine.
High‐Pressure, High‐Resolution Nuclear Magnetic Resonance (HPHR‐NMR.): A Tool in Chemical Kinetics
Authors: Merbach André E. , Vanni H.
Published: December 2004

In recent years the volume of activation Δ V* has become a powerful tool in chemical kinetics. High resolution NMR. spectroscopy is now one of the most common techniques used in the study of the kinetics of labile chemical systems. In order to measure Δ V* by this technique, we have built a 1H‐probe‐head, for a Fourier transform spectrometer, working up to 4 kbar and with a resolution of 0.6 Hz. The temperature is regulated and measured with an accuracy better than 0.2°. The high pressure probe‐head has been tested on a chemical system showing a dissociative‐associative crossover for the ligand substitution mechanism. It had been shown previously that the ligand exchange TaBr5 · L + *L ⇄ TaBr5 · *L + L proceeds via a D mechanism when L=Me2O, and via an Ia mechanism when L=Me2S. As expected, ΔV is positive (+30.5 ± 2.0 cm3 mol−1) for the dissociative process and negative (−12.6 ± 1.0 cm3 mol−1) for the associative one.
Synthese von vier chiralen, elektrophilen C3‐ und C4‐Synthesebausteinen aus Hydroxycarbonsäuren
Authors: Seuring Bernhard , Seebach Dieter
Published: December 2004

Synthesis of four chiral electrophilic C3‐ and C4‐synthons from hydroxycarboxylic acids

The chiral alkylating reagents4,6c, and10a/bare prepared from lactic, β‐hydroxy butyric, and malic acid, respectively. Their use in natural product synthesis is referred too.
Nucleoside und Nucleotide. Teil 10. Synthese von Thymidylyl‐(3′‐5′) ‐thymidylyl‐(3′‐5′)‐1‐(2′‐desoxy‐β‐D‐ribofuranosyl)‐2(1 H)‐pyridon
Authors: Cerletti Nico , Tamm Christoph
Published: December 2004

Nucleosides and Nucleotides. Part 10. Synthesis of Thymidylyl‐(3′‐5′)‐thymidylyl‐(3′‐5′)‐1‐(2′‐deoxy‐β‐D‐ ribofuranosyl)‐2(1 H)‐pyridone

The synthesis of 5′‐O‐monomethoxytritylthymidylyl‐(3′‐5′)‐thymidylyl‐(3′‐5′)‐1‐(2′‐deoxy‐β‐D‐ribofuranosyl)‐2(1H)‐pyridone ((MeOTr)TdpTdp∏d, 5) and of thymidylyl‐(3′‐5′)‐thymidylyl‐(3′‐5′)‐1‐(2′‐deoxy‐β‐D‐ribofuranosyl)‐2(1 H)‐pyridone (TdpTdp∏d, 11) by condensing (MeOTr) TdpTd (3) and p∏d(Ac) (4) in the presence of DCC in abs. pyridine is described. Condensation of (MeOTr) TdpTdp (6) with Πd(Ac) (7) did not yield the desired product 5 because compound 6 formed the 3′‐pyrophosphate. The removal of the acetyl‐ and p‐methoxytrityl protecting group was effected by treatment with conc. ammonia solution at room temperature, and acetic acid/pyridine 7 : 3 at 100°, respectively. Enzymatic degradation of the trinucleoside diphosphate 11 with phosphodiesterase I and II yielded Td, pTd and p∏d, Tdp and Πd, respectively, in correct ratios.
An Efficient Approach to Patchouli Alcohol Analogues
Authors: Näf Ferdinand , Decorzant René , Thommen Walter
Published: December 2004

A short approach to the tricyclo [5.3.1.03,8] undecane derivatives 1, 10, 11 and 12 and to the tricyclo [4.3.1.03,7] decane derivative 2, starting from industrially available intermediates, is described. Of the compounds 1, 10, 11, and 12, which possess the ring system of patchouli alcohol, 12 also exhibits a woody, patchouli‐like note. The 1H‐NMR.‐spectra of 1, 2 and 8–12 are discussed.
Stereoselektivität und Reaktivität bei der 1,3‐dipolaren Cycloaddition chiraler N‐(Alkoxyalkyl)nitrone
Authors: Vasella Andrea
Published: December 2004

Stereoselectivity and Reactivity in the 1,3‐Dipolar Cycloaddition of Chiral N‐(Alkoxyalkyl)nitrones

The stereoselectivity in the reaction of hydroxy‐oxime 1 with acetaldehyde and methyl methacrylate yielding the diastereomeric isoxazolidine‐ribosides 9–12 was determined to be 93%. The predominant adducts 9 and 10 were cleaved to the diastereomeric isoxazolidines 19 and 20, respectively, which upon oxidation gave the same optically active 2‐isoxazoline 21, thus demonstrating the participation in the cycloaddition of both (E/Z)‐isomeric nitrones 13 and 14. Based upon comparison of the optical rotations, the isoxazolidines 7, 8, 19 and 20 and the 2‐isoxazolines 21 and 22 possess the same chirality, found to be R by correlating 7 with (+)‐(S)‐citramalic acid. ‐ Since the hydroxy‐oximes 1 and 36 showed the same stereo‐selectivity in the reaction with formaldehyde and methyl methacrylate, the trityl group of 1 does not influence the stereoselectivity in the cycloaddition. The hydroxyoxime 38 led in the same type of reaction to the isoxazolidines 7, 8, 19 and 20 possessing (S)‐chirality, the stereoselectivity (79–95%) being similar to the one observed with 1 (67–95%). The explanation of this stereoselectivity is based upon a stereoelectronic effect in the transition state of the cycloadditions (kinetic anomeric effect). As predicted, the N‐(alkoxyalkyl)nitrones showed enhanced reactivity in the cycloaddition with unactivated olefins (leading to 47, 48, 50 and 51). The importance of exo vs. endo approach of the dipolarophile was evidenced by reacting 1 with formaldehyde and methyl acrylate giving predominantly 57 with (5S)‐configuration. ‐ Use of the hydroxy‐oxime 65 allows synthesis of optically active isoxazolidines with regeneration of the starting hydroxy‐oxime.
Diénamines hétérocycliques. III. Réexamen de la réaction de la base de Fischer avec le tétracyanoéthylène
Authors: Hubschwerlen Christian , Fleury Jean‐Pierre , Fritz Hans
Published: December 2004

Heterocyclic dienamines III. A re‐examination of the reaction of Fischer's base on tetracyanoethylene

Depending on the order of addition, Fischer's base 5 (1,3,3‐trimethyl‐2‐methylidene‐indoline) reacts 1:1 with tetracyanoethylene to give either the tricyanovinylation product 6 or the spiro compound 7. A skeletal rearrangement of a zwitterionic intermediate can explain the formation of the spiro compound. The latter undergoes a thermal isomerization yielding by ring expansion the tetrahydroquinoléine 8. On reaction with LiAlH4 or CH3ONa 7 and 8 lead both to triazatetracycles. All structures are assigned on the basis of spectral data.
Note sur quelques complexes entre nicéthamide (N,N‐diéthyl‐nicotamide) et/ou de la pémoline (phényl‐5‐imino‐2‐oxazolidone‐4) et divers sels, particulièrement de sels calciques de monoesters aminoalkylphosphoriques
Authors: Rabinowitz J. , Thorndahl S. , Gold‐Aubert Ph.
Published: December 2004

Note on some complexes between nikethamide and/or pemoline with various salts, especially calcium aminoalkylphosphates

A number of binary and ternary complexes of nikethamide and/or pemoline with various calcium salts, particularly calcium aminoalkylphosphates, have been prepared in order to assess their pharmacological properties. The formation of such complexes has been established by IR. spectroscopy.
Zum basenkatalysierten H/D‐Austausch des acetylenischen Wasserstoffatoms in aromatischen Alkinylverbindungen
Authors: Kramis Jost , Hansen Hans‐Jürgen
Published: December 2004

On the Base‐Catalysed H/D‐Exchange of the Acetylenic Hydrogen Atom in Aromatic Alkynyl Compounds

H/D‐exchange rates for a number of compounds of the general type 1 (X = p‐CH3O, m‐CH3O, p‐CF3, m‐CF3, p‐CH3, p‐Cl, H; Z  O, NH, CH2) were determined in N‐methyl‐pyrrolidine (NMP)/D2O mixtures at 25° (see Table 1).

It is shown that the log k values of the H/D‐exchange correlate nicely (r = 0.995) with the chemical shift of the acetylenic proton in 1. Thus, the H/D‐exchange rate is given by log k (min−1) = 2.91 · δ (ppm) ‐ 7.79 for the NMP/D2O mixture at 25°.
Neue 18‐substituierte Steroide. I. 18‐Methylidenprogesteron über Steroide 232. Mitteilung
Authors: Kalvoda Jaroslav , Grob Jürgen , Anner Georg
Published: December 2004

New 18‐Substituted Steroids. I. 18‐Methylideneprogesterone

Three independent syntheses of 18‐methylideneprogesterone, the first representative of a new group of biologically highly active steroidal compounds, are described. In the first approach 3‐acetoxy‐20‐oxo‐5‐pregnen‐18‐carbonitril (2) is transformed into the final product by a reaction sequence involving the Cope degradation of the N‐oxide 6 of the corresponding tertiary aminomethyl derivative. The Wittig reaction 3,3,20,20‐Bis(äthylendioxy)‐5‐pregnen‐18‐al (11) represents the crucial step in the second synthesis. In the last procedure the 18‐methylidene‐20‐oxo grouping is generated by fragmentation of an 18,21‐bridged 1,3‐diol system (19). The two former methods are very versatile and generally applicable for the synthesis of other analogues.
Ringschlussreaktionen mit 2‐(β‐Styryl)benzylaminen 5‐Phenyl‐1H‐2‐benzazepine. 23. Mitteilung über siebengliedrige Heterocyclen
Authors: Gast Gérard , Schmutz Jean , Sorg Dieter
Published: December 2004

Cyclization reactions with 2‐(β‐styryl)benzylamines 5‐Phenyl‐1H‐2‐benzazepines

Cyclization of the urea derivative 3 with POCl3 to give 2‐(4‐methyl‐1‐piperazinyl)‐4‐phenylquinoline (4) was carried out in analogy to the quinoline synthesis of Foulds & Robinson. This reaction was used for the preparation of 2‐benzazepines. The trisubstituted ureas 6 and 8, derived from the 2‐(β‐styryl)‐benzylamines 5, were cyclized with POCl3 to yield the 3‐amino‐5‐phenyl‐1H‐2‐benzazepines 7 and 9, respectively. Similarly, cyclization of the corresponding acetyl‐derivatives 10 gave the 3‐methyl‐5‐phenyl‐1H‐2‐benzazepines 12. On the other hand, the disubstituted urea 15, cyclized under the same conditions to the 1‐methyl‐1‐phenylisoindoline derivative 16, and 2‐(β‐styryl)benzylamine (5a) on treatment with phosgene gave the isoindoline 17 in an analogous manner.
Solvolytic Ring‐opening of Alkoxychlorofluorocyclopropanes: A Ready Access to Fluorinated α,β‐Unsaturated Aldehydes and Ketones
Authors: Bessière Yvonne , Savary Dang Ngoc‐Huê , Schlosser Manfred
Published: December 2004

Alkoxychlorofluorocyclopropanes are easily prepared by chlorofluorocarbene addition to en‐ethers in a two‐phase system and converted by simple heating in an aqueous solvent mixture to 2‐fluoro‐2‐alkenals which can be reduced to the corresponding alcohols.
Zur Biogenese des Muscarins in Mycelkulturen von Clitocybe rivulosa
Authors: Nitta Keiichi , Stadelmann René Josef , Eugster Conrad Hans
Published: December 2004

Studies on the biosynthesis of muscarine in mycelial cultures of Clitocybe rivulosa

The incorporation and distribution of several 14C‐labelled simple compounds into muscarine has been investigated with mycelial cultures of Clitocybe rivulosa. Specifically, the carbon atoms 1, 2 and 3 of pyruvate are incorporated into CH3‐C(2), C(2) and C(3), and the carbon atoms 2, 3 and 4 of glutamate into C(4), C(5) and CH2‐C(5) of muscarine. The carbon atoms 1 and 5 of glutamate are lost during the biosynthesis. Therefore, muscarine can be regarded as a derivative of glutamate.
Zur Kenntnis des Aminal‐Enamin‐Gleichgewichtes bei Cyclopropan‐carbaminalen
Authors: Huber Martin K. , Martin Roger , Rey Max , Dreiding André S.
Published: December 2004

The Aminal‐enamine Equilibrium in Cyclopropane‐carbaminals.

The following cyclopropane‐carbaminals were synthesized: N,N′‐(T‐2,t‐3‐dimethyl‐r‐1‐cyclopropyl)methylene‐dipyrrolidin (15), the corresponding (c‐2, c‐3)‐isomer 16, N,N′‐(cyclopropyl)methylene‐dipyrrolidin (17) and N,N′‐(c‐2, t‐3‐diphenyl‐r‐1‐cyclopropyl)methylene‐dipyrrolidin (18). Their constitutions and configurations were derived from the method of synthesis and from 1H‐NMR.‐spectra. The c‐c‐r‐1‐dimethyl‐aminal 16 rearranged at room temperature to its t‐t‐r‐1‐dimethyl‐isomer 15. This demonstrates the existance of an aminal‐enamine equilibrium for cyclopropane‐carbaminals although cyclopropane‐carbenamines have not been isolated as yet. The kinetic data found for the rearrangement of 16 to 15 are compatible with two mechanisms: In the first one, the protonated aminal 21 decomposes into the iminium‐ion 22, which, in turn, yields the enamine 19. In the second one, 21 is converted to 19 in a single step. The formation of cyclopropyl‐pyrrolidino‐acetonitrile (26) and dipyrrolidino‐ethylene‐1,1‐dicarbonitrile (27) from the reaction of the aminal 17 with tetracyanoethylene may also be explained with an aminal‐enamine equilibrium. ‐ This equilibrium lies strongly on the side of the aminal. Investigations of the aminal‐enamine ratio of several cycloalkanecarbaminals, namely of the 3‐ring derivative 17, the 4‐ring derivative 35 and the bicyclic 5‐ring derivative 38, show that ring strain is a determining factor for the equilibrium bias. This strain may also explain that the aminomethanol 41 was isolable.

Some of the aminals were synthesized from previously unknown aldehydes. t‐2, t‐3‐dimethyl‐r‐1‐cyclopropane‐carbaldehyde (11) and its (c‐2, c‐3)‐isomer 12 were obtained by stereoselective ring‐contraction of the 2‐chloro‐cyclobutanols 46 and 48/49, respectively. The configurations of the aldehydes 11 and 12, of the starting cyclobutanones 44 and 45 and of the cyclobutanol 46 were established by 1H‐NMR. measurements. From the steric course of the ring contraction it can be concluded that it is the fastest rearrangement of 2‐halo‐cyclobutanols with base, when the conformation having an equatorial halogen atom is not obstructed. c‐2, t‐3‐diphenyl‐r‐1‐cyclopropane‐carbaldehyde (14) and 3‐phenyl‐1‐cyclobutane‐car‐baldehyde (34) were synthesized by reduction of the corresponding ester 50 and acid 52, respectively, followed by Sarett‐oxidation.