bluuebunny/crossref_metadata_2025 huggingface dataset:
Angiotensin‐II Analogues. I: Synthesis and incorporation of the halogenated amino acids 3‐(4′‐iodophenyl)alanine, 3‐(3′,5′‐dibromo‐4′‐chlorophenyl)alanine, 3‐(3′,4′,5′‐tribromophenyl)alanine, and 3‐(2′,3′,4′,5′,6′‐pentabromophenyl)alanine
Authors: Leduc Richard , Bernier Michel , Escher Emanuel
Published: December 2004

The synthesis of the polyhalogenated phenylalanines Phe(3′,4′,5′‐Br3) (3), Phe(3′,5′‐Br2‐4′‐Cl) (4) and DL‐Phe (2′,3′,4′,5′,6′‐Br5) (9) is described. The trihalogenated phenylalanines 3 and 4 are obtained stereospecifically from Phe(4′‐NH2) by electrophilic bromination followed by Sandmeyer reaction. The most hydrophobic amino acid 9 is synthesized from pentabromobenzyl bromide and a glycine analogue by phase‐transfer catalysis. With the amino acids 4, 9, Phe(4′‐I) and D‐Phe, analogues of [1‐sarcosin]angiotensin II ([Sar1]AT) are produced for structure‐activity studies and tritium incorporation. The diastereomeric pentabromo peptides L‐ and D‐13 are separated by HPLC. and identified by catalytic dehalogenation and comparison to [Sar1]AT (10) and [Sar1, D‐Phe8]AT (14).
1,3‐Dipolare Addition von 2‐Benzonitrilio‐2‐propanid an 7‐Methylthieno[2,3‐c]pyridin‐1,1‐dioxid und Folgereaktionen
Authors: Fischer Ulf , Schneider Fernand
Published: December 2004

1,3‐Dipolar Addition of 2‐Benzonitrilio‐2‐propanid to 7‐Methylthieno[2,3‐c]pyridine 1,1‐Dioxide and Subsequent Reactions

The addition of dipole 2, generated photochemically from 2,2‐dimethyl‐3‐phenyl‐2H‐azirine (1), to 7‐methylthieno[2,3‐c]pyridine 1,1‐dioxide yields the pyrroline derivative 4 as a major product and regioisomer 5 in low yield. Compound 4 can be transformed into the pyrrolidine derivative 11 by ring opening, loss of SO2 and hydrogenation. Bromopyrroline derivative 14 gives either by dehydrohalogenation compound 18 or, by substitution, nitrile 17 or ethoxy derivative 19. Substitution of 14 and ring opening yields methoxypyrrole derivative 20, which gives access to the unstable hydroxypyrrole and hydroxypyrrolidine derivative 28 resp. 30. The vinylsulfone 18 is the starting material for addition‐ring‐cleavage reactions. Oxidation of pyrroline derivative 4 gives epoxy‐substituted N‐oxide 39 and di‐N‐oxide 40; and oxidative transformation of pyrrolidine derivative 11 yields the (hydroxymethyl)pyridylpyrrolidine derivative 45.
Stromloser Ionentransport und Potentiometrie an Membranen mit Chromoionophoren für Li+und UO
Authors: Villiger Alois , Morf Werner E. , Simon Wilhelm
Published: December 2004

Zero‐current Ion‐transport Studies and Potentiometric Measurements on Membranes Containing Chromoionophores for Li+and UO

Non‐macrocyclic ionophores for Li+and UOhave been substituted with a diphenylmaleimide unit. In membranes the obtained chromoionophores induce the same ion‐selectivity and ion‐transport behavior as the unsubstituted ligands.
Synthesis and Anaphylactogenicity of Monohaptenic Carbohydrate Conjugates
Authors: Guenin Raymond , Schneider Conrad H.
Published: December 2004

Peptidic model conjugates carrying a single 2‐carboxy‐4,6‐dinitrophenyl haptenic group, and as carbohydrate moieties D‐gluconoyl, β‐D‐mannopyranosyl, 2‐deoxy‐β‐D‐glucopyranos‐2‐yl, or lactobionoyl residues, including the pseudocarbohydrate residue 1,3,4,5‐tetrahydroxycyclohexane‐1‐carbonyl, were synthesized. Conjugates carrying the lactobionoyl of the bis(2‐deoxy‐β‐D‐glucopyranos‐2‐yl) moiety were anaphylactogenic in the guinea pig, passively sensitized against 2‐carboxy‐4,6‐dinitrophenyl antigen.
Highly Stereoselective Total Syntheses of (±)‐Chelidonine and of (±)‐Norchelidonine by an Intramolecular o‐Quinodimethane/Nitrostyrene‐Cycloaddition
Authors: Oppolzer Wolfgang , Robbiani Christian
Published: December 2004

Conversion of 2‐bromomethylstyrene 22 and benzocyclobutenyl carbamate 28 to the benzophenanthridine alkaloids (±)‐chelidonine (1, five steps, 25% from 28) and to (±)‐norchelidonine (2, six steps, 24% from 28) are described. The key step 29 → 31 involves a highly regio‐ and stereocontrolled intramolecular Diels‐Alder reaction of the (E)‐quinodimethane 30.
The Formulation of Four‐Components Practically Perfluorinated Microemulsions
Authors: Oliveros Esther , Maurette Marie‐Thérèse , Braun André M.
Published: December 2004

Microheterogeneous systems consisting of sodium perfluorooctanoate (1), 2, 2, 3, 3, 4, 4, 4‐heptafluoro‐1‐butanol (2), perfluorohexane (3) and water, representing the first practically perfluorinated microemulsions based on ionic surfactants have been formulated. A pseudoternary phase diagram shows a central region of turbid or transparent gels and two regions of monophasic systems (O/W‐ and W/O‐microemulsions) which have been characterized by NMR. spectroscopy.
The Adamantane Rearrangement of 1,2‐Trimethylenenorbornanes. III. AlBr3‐catalyzed rearrangement to 2,6‐trimethylenenorbornane
Authors: Klester Alfred Michael , Ganter Camille
Published: December 2004

From treatment of D‐labelled 1, 2exo‐, 1, 2endo‐ and 2endo, 6endo‐trimethylene‐norbornane (1, 2 and 3, resp.) with aluminum bromide in carbon disulfide, the evidence is gained that a degenerate rearrangement is involved in the admantane rearrangement of both 1 and 2 to 3.
Photochemical Reactions. 129th Communication. Photochemistry of a conjugated diepoxydiene: Product formation via carbonyl ylide and carbene intermediates with participation of neighbouring epoxy functions
Authors: Bischofberger Norbert , Frei Bruno , Jeger Oskar
Published: December 2004

On singlet excitation (λ=254 nm, acetonitrile) the diepoxydiene (E)‐7 undergoes photocleavage to the carbonyl ylide VII and the carbenes X and XI. The carbonyl ylide VII rearranges to the thermally labile dioxabicyclo [3.2.1]octene 20 or fragments via VIII to the aldehyde 9 and propyne. The carbene X, showing behaviour typical of vinyl carbenes, undergoes addition to the adjacent double bond furnishing the cyclopropene 11. The carbene XI, however, undergoes an insertion reaction into the neighbouring oxirane C,C‐bond leading to the oxetene (E)‐21 which can be isolated at −78°, but at room temperature is rapidly transformed to the aldehyde 10. On triplet excitation (acetone, λ>280 nm), however, (E)‐7 shows the typical behaviour of epoxydienes, undergoing C, O‐cleavage of the oxirane and isomerization to 22, 23 and (E/Z)‐24.
31P‐NMR and X‐Ray Studies of the Complexes [HgX2 (1)]. (1=2, 11‐bis (diphenylphosphinomethyl)benzo [c]phenanthrene, X=Cl, I)
Authors: Kunz Roland W. , Pregosin Paul S. , Camalli Mercedes , Caruso Francesco , Zambonelli Luigi
Published: December 2004

The 31P{1H}‐NMR characteristics of the complexes [HgX2(1)] and [HgX2‐(PPh2Bz)2] (X = NO3, Cl, Br, I, SCN, CN) and the solid state structures of the complexes [HgCl2(1)] and [HgI2(1)] (1 = 2,11‐bis (diphenylphosphinomethyl)benzo‐[c]phenanthrene) have been determined.

The 1J(199Hg, 31P) values increase in the order CN < I < SCN < Br < Cl < NO3. The two molecular structures show a distorted tetrahedral geometry about mercury. Pertinent bond lengths and bond angles from the X‐ray analysis are as follows: HgP = 2.485(7) Å and 2.509 (8) Å, HgCl = 2.525 (8) Å and 2.505 (10) Å, PHgP = 125.6(3)°, ClHgCl = 97.0(3)° for [HgCl2(1)] and HgP = 2.491 (10) Å and 2.500(11) Å, HgI = 2.858(5) Å and 2.832(3) Å, PHgP = 146.0(4)°, IHgI = 116.9(1)° for [HgI2(1)]. The equation, derived previously, relating 1J(199Hg, 31P) and the angles PHgP and XHgX is shown to be valid for 1.
The Tautomerism of 1,3,4‐Thiadiazol‐2 (3H)‐ones. A 15N‐NMR‐Study
Authors: Fritz Hans , Kristinsson Haukur , Winkler Tammo
Published: December 2004

5‐Substituted 1,3,4‐thiadiazol‐2(3H)‐ones were shown to exist almost exclusively in the oxo tautomeric form with the aid of proton‐coupled 15N‐NMR spectra using the corresponding 3‐methyl‐1,3,4‐thiadiazol‐2(3H)‐ones and 5‐substituted‐2‐methoxy‐1,3,4‐thiadiazoles as reference compounds.
New Synthetic Routes to β‐Olefinic Triphenylphosphonium Salts via (Diolefin)tricarbonyliron Complexes
Authors: Salzer Albrecht , Hafner Andreas
Published: December 2004

The regio‐ and stereospecific preparation of β‐olefinic triphenylphosphonium salts, starting from (diolefin)tricarbonyliron compounds is described. The latter are converted by various routes into either [(allyl)Fe(CO)4]+ ‐ or [(dienyl)Fe(CO)3]+ ‐ derivatives. The allylic cations, when reacted with P (C6H5)3, yield uncomplexed (2‐en‐l‐yl)triphenylphosphonium salts in good yields, while treatment of the dienyl cations with P(C6H5)3 leads to the quantitative formation of (2,4‐diene‐l‐yl)triphenylphosphonium ions still coordinated to the Fe (CO)3‐moiety. A method of oxidative decomplexation is described, by which the free phosphonium salts can be obtained.

All new compounds were characterized by 13C‐NMR spectra and also, where necessary, by 1H‐NMR decoupling experiments to confirm the stereochemical assignments. Many of the new phosphonium salts, potentially useful as Wittig reagents for natural product syntheses, are difficult to obtain by conventional unequivocal routes.
Die Synthese von 7‐anti‐substituierten 2‐exo‐ und 2‐endo‐Norbornanolen. Norbornanreibe. 13. Mitteilung
Authors: Flury Peter , Grob Cyril A.
Published: December 2004

The Synthesis of 7‐anti‐Substituted 2‐exo‐ and 2‐endo‐Norbornanols

The title compounds and the corresponding p‐toluenesulfonates were prepared in connection with a mechanistic study of C‐participation in carbocations.
Neue Heteroarene: Synthese und spektrale Daten von Indolizino[6,5,4,3‐aij]chinolin («Ullazin») und einigen Derivaten
Authors: Balli Heinz , Zeller Martin
Published: December 2004

New Heteroarenes: Synthesis and Spectroscopic Properties of Indolizino[6,5,4,3‐aij]quinoline (‘Ullazine’) and of some Derivatives

The synthesis, 1H‐NMR, 13C‐NMR and electronic absorption spectra of indolizino[6,5,4,3‐aij]quinoline (6a), a new π‐excess heteroarene, and of three 3,9‐disubstituted derivatives are described.
Michael Addition of Lithio‐α‐(methyldiphenylsilyl)acetate to Cyclopentenone: A direct synthesis of (±)‐methyl jasmonate
Authors: Oppolzer Wolfgang , Guo Modao , Baettig Kurt
Published: December 2004

Aprotic 1,4‐addition of a lithiated α‐(methyldiphenylsilyl)acetate to cyclopentenone andin situenolate alkylation provides a direct synthesis of (±)‐methyl jasmonate(Scheme 3).
Zur Verwendbarkeit von 13C‐Substituenteninkrementen bei 1,4‐Benzo‐ und 1,4‐Naphthochinonen
Authors: Neidlein Richard , Kramer Walter , Leidholdt Rolf
Published: December 2004

About the Availability of 13C‐NMR Substituent Increments in 1,4‐Benzo‐ and 1,4‐Naphthoquinones

The 13C‐NMR spectra of a number of substituted 1,4‐benzo‐ and 1,4‐naphthoquinones have been obtained and assigned. Effects of CH3‐, O‐alkyl‐, Cl‐, NH2‐ and N3‐ substituents have been deduced for the quinoid part of the molecules and used for the calculation of 13C‐chemical shifts.
Cyclometalated Arylazo Compounds. Part 4. ortho‐cyano‐1‐arylazonaphthalenes and 3‐amino‐2‐arylbenzo [g]indazoles from cyclopalladated 1‐arylazonaphthalenes. 4th communication on compounds with a metal‐arene σ‐bond
Authors: Gehrig Kurt , Klaus Alfred J. , Rys Paul
Published: December 2004

The reaction of a cyclopalladated 1‐arylazonaphthalene with tetrabutylammonium cyanide leads to an ortho‐cyano‐1‐arylazonaphthalene and a 3‐amino‐aryl‐benzo[g]indazole, depending upon whether triphenylphosphine or 1,2‐bis(diphenyl‐phosphino)ethane (DIPHOS) is used to monomerize the binuclear Pd(II)‐complex. In a similar insertion reaction with cyclohexyl isocyanide the corresponding 3‐(N‐cyclohexyl)‐aminoindazole is formed. A Pd(II)‐isocyano complex is shown to be a possible intermediate in that conversion.
Zum Mechanismus der Photoreduktion von Wasser mit Ruthenium‐trisbipyrazil als Sensibilisator
Authors: Dürr Heinz , Dörr Gisela , Zengerle Klaus , Curchod Jean‐Marc , Braun Andre M.
Published: December 2004

On the Mechanism of the Photoreduction of Water with Ruthenium‐trisbipyrazil as Sensitizer

Oxidative and reductive primary steps can be differentiated in using Ru(bipy) and Ru(bipz), respectively, as sensitizers in a photochemically induced, Pt‐catalyzed sacrificial water reduction. Experimental evidence for the reductive primary step and kinetic data are given for the electron transfer to methylviologen as relay compound.
Intramolecular Carbenoid Reactions of Pyrrole Derivatives Efficient Syntheses of Pyrrolizinone and Dihydroindolizinone
Authors: Jefford Charles W. , Johncock William
Published: December 2004

The copper‐catalyzed pyrolysis of 1‐diazo‐3‐(pyrrol‐1‐yl)‐2‐propanone (1a) and 1‐diazo‐4‐(pyrrol‐1‐yl)‐2‐butanone (1b) in benzene solution gave 1 H‐pyrrolizin‐2‐(3H)‐one (4a) and 5,6‐dihydroindolizin‐7 (8H)‐one (4b), respectively, in quantitative yield. Similar pyrolysis of 1‐diazo‐4‐(3‐methylindol‐1‐yl)‐2‐butanone (9) was less efficient giving 1‐methylbenzo[b]‐5,6‐dihydroindroindolizin‐7 (8H)‐one (10) and 4‐(3‐methylindol‐1‐yl)‐but‐l‐en‐3‐one (11) in 7% and 24% yield, respectively.
Ringtransformationen von 3‐substituiertem 5‐Trifluormethyl‐1,3,4‐thiadiazol‐2(3H)‐on mit Nucleophilen
Authors: Kristinsson Haukur , Winkler Tammo , Mollenkopf Max
Published: December 2004

Ring Transformations of 3‐Substituted 5‐Trifluoromethyl‐1,3,4‐thiadiazol‐2(3H)‐one with Nucleophiles

The 3‐chlormethyl‐5‐trifluoromethyl‐1,3,4‐thiadiazolone 3 undergoes a ring transformation to 3‐acylated 2,3‐dihydro‐1,3,4‐thiadiazoles 4 with many nucleophiles. Upon formal replacement of the chloromethyl group in the 3‐position of 3 by an extended bromoalkyl chain (→9a‐c), the reaction with nucleophiles yields 4‐acylated 5,6‐dihydro‐4H‐1,3,4‐thiadiazines 10 (from 9a), 4,5,6,7‐tetrahydrothiadiazepines 13 (from 9b) and 5,6,7,8‐tetrahydro‐4H‐1,3,4‐thiadiazocines 14 (from 9c) by ring enlargement. The 3‐propargyl‐thiadiazolone 17 rearranges with nucleophiles to 4‐acylated 6‐methylidene‐5,6‐dihydro‐4H‐1,3,4‐thiadiazines 18. The structures of the new compounds were elucidated by 1H‐ and 13C‐NMR spectroscopy.
Immobilized Enzyme Particles Prepared by Radiation Polymerization of Polyurethane Prepolymer
Authors: Kumakura Minoru , Kaetsu Isao
Published: December 2004

The immobilization of enzymes such as cellulase by radiation polymerization of dispersed polyurethane prepolymer was studied using tolylene‐2,4‐diisocyanate and 2‐hydroxyethyl methacrylate. The polyurethane particles were obtained by the dispersion of polyurethane prepolymer followed by radiation polymerization, in which the enzyme was immobilized on its surface by convalent bonding. The particle diameter of immobilized enzyme particles varied with monomer concentration and composition. The enzymatic activity of immobilized enzyme particles varied with the temperature of dispersion and irradiation, and decreased with increasing particle diameter.
Interactions between Functional Groups. Part I. Crystal Structure of 2‐Phenylethynyl‐N,N‐dimthlaniline at 98 K: A Remarkably Short CH …︁ C Distance
Authors: Wallis John D. , Dunitz Jack D.
Published: December 2004

In the crystal structure of the title compound at 98 K the dimethylamino group has pyramidal geometry. The nitrogenlone pair is not directed towards the triple bond; instead, one NCH3 bond lies almost in the plane of the disubstituted ring, directed away from the triple bond, while the other NCH3 bond and the lone pair are directed to opposite sides of the plane, nearer to the acetylene. There is a remarkably short intramolecular contact (2.39 Å) between a methyl H‐ and an acetylenic C‐atom. The Taft σI parameter of the arylethynyl substituent appears to be similar to that of a carboxylic ester, judging from the bond‐angle deformation at the ipso‐C‐atom.
On the Structure of Oxirane Molecular Cation. Preliminary Communication
Authors: Bally Thomas , Nitsche Stephan , Haselbach Edwin
Published: December 2004

A recent controversy on the interpretation of the ESR spectrum of ionized oxirane is clarified on the basis of the electronic absorption spectra of ionized tetramethyloxirane and 9,10‐octalineoxide. The results favour a ring‐opened structure for oxirane molecular cation, resulting from CC bond cleavage and being iso‐π‐electronic to allyl radical.
Palladium‐promoted Cyclization of Tetra‐alkylated 1‐Arylazonaphthalenes to 2‐Aryl‐benzo[g]indazoles
Authors: Hugentobler Max , Klaus Alfred J. , Ruppen Peter , Rys Paul
Published: December 2004

1‐Arylazonaphthalenes with all the potential cyclopalladation sites (one peri‐ and three ortho‐positions) substituted by methyl or ethyl groups react with stoicheiometric or catalytic amounts of sodium tetrachloropalladate(II) to the corresponding 2‐arylbenzo[g]indazoles. Possible mechanisms for the catalytic cyclization reaction are proposed.
Über Poterinchemie. 82. Mitteilung. Bildung von Formimidoyl‐Derivaten aus Aminen und Benzylisocyanid; Eine neue Umpolungsmöglichkeit für bestimmte C‐Atome
Authors: Ganguly Subhendu N. , Viscontini Max
Published: December 2004

Formation of Formimidoyl Derivatives from Amines and Benzylisocyanide; A New Possibility of Umpolung for Certain C‐Atoms

Cu(I)Cl can give a colorless and well‐crystallized complex with 4 molecules of benzylisocyanide. This complex is able to transfer the benzylisocyanide ligands to primary and secondary amines and to form N‐benzylformimidoyl derivatives. Catalyic hydrogenolysis removes the benzyl group, and free formimidoyl compounds are obtained in good yield. The method which succeeds with aliphatic amines, could not be applied to the secondary amino group of tetrahydropterines.
Molecular Ions of Transient Species: Vinyl‐Alcohol Cation
Authors: Albrecht Bruno , Allan Michael , Haselbach Edwin , Neuhaus Louis , Carrupt Pierre‐Alain
Published: December 2004

Vinyl alcohol 1 was prepared by thermolysis of cyclobutanol and its photoelectron spectrum was determined. I = 9.18 eV and I = 9.52 eV were found, the vibrations progression (ṽ = 1400 cm−1) for this lowest energy transition 1(X)→1+(X̃) indicating significant skeletal changes in the ion. The question of the relative stability of the syn (1)‐ vs. anti‐ions (1) is discussed in the light of theoretical calculations. The energy of the second π‐state of 1+ is estimated at 13.6–14.1 eV above the ground state of 1.
Synthese von Bicyclo[3.3.o]oct‐1(5)en‐2‐on aus Cyclohexanon
Authors: Lorenzi‐Riatsch Annalaura , Nakashita Yoshihiko , Hesse Manfred
Published: December 2004

Synthesis of Bicyclo[3.3.0]oct‐1(5)en‐2‐one from Cyclohexanone

Treatment of 2‐nitrocyclohexanone (2) with acrylaldehyde yielded in the presence of tetrabutylammonium fluoride the bicyclic product 5, which was oxidized to the nitro‐diketone 3. The conversion of 3 to the title compound 1 was achieved in the nearly quantitative yield under unusual conditions: K2CO3/H2O and H2SO4. Compound 3, was also converted to 1 (stepwise and one‐pot reaction, respectively) by treatment with 1. NaOCH3, 2. TiCl3, and 3. H2SO4 (Scheme).
Protolytic Opening of Two Diastereoisomeric Cyclopropanols
Authors: Schönholzer Peter , Wan Terence S. , Fischli Albert
Published: December 2004

Cob(I) alamin (1(I))‐catalyzed reduction of the aldehyde 2 led to the two crystalline cyclopropanols 3 and 4 (see Scheme 2). The protolytic ring‐opening starting from 3 produced the saturated aldehydes 6 and 7;8 was formed in traces only (see Scheme 3). The protolysis starting from 3 led, therefore, mainly to retention of configuration at the spiro C‐atom (7); ring‐opening with inversion was observed in traces only (8). Starting from 4, the protolysis produced 9 and 7; the absence of 8 showed this protolysis to proceed 9 and 7; the absence of 8 showed this protolysis to proceed exclusively with inversion of configuration at the spiro center. Of the p‐bromobenzoate 5 (cf. Scheme 2) the structure has been determined by X‐ray analysis.
Stoffwechselprodukte von Mikroorganismen 226. Mitteilung Versuche zur Strukturaufklärung von Niphimycin, 3. Teil. Identität von Scopafungin mit Niphimycin I und Lage des Malonylrestes in Niphimycin und Copiamycin
Authors: Gassmann Peter , Hagmann Leonhard , Keller‐Schierlein Walter , Samain Daniel
Published: December 2004

Structural Elucidation of Niphimycin, Part 3. Identity of Scopafungin and Niphimycin I. Position of the Malonyl Residue of Niphimycin and Copiamycin

The identity of scopafungin with niphimycin I was proven by spectroscopic and chromatographic methods and by common degradation products. The position of the malonyl residue in niphimycin I (9) and in copiamycin (14) was deduced by 1H‐NMR spin‐decoupling experiments of a degradation product (10).
Preparation of Bicyclo[3.3.0]octane‐2,8‐dione‐ and Declain‐1,8‐dione‐Derivatives
Authors: Duthaler Rudolf O. , Maienfisch Peter
Published: December 2004

Alkylation of bicyclo[3.3.0]octane‐2,8‐dione (1), which is prepared by a modification of the procedure described in the literature, gives the methyl‐ and propynyl‐derivatives6and7(Scheme 1). In addition to the method described previously (Scheme 2), 9‐methyl‐cis‐decalin‐1,8‐dione9is obtainable stereoselectively either by cyclization of keto‐acid16, or by aldol cyclization of keto‐aldehyde26and oxydation of the resulting alcohols24and25(Scheme 4). The β‐keto‐alcohols24and25undergo a base‐catalyzed isomerization; thetrans‐decalin isomers27and28are not detected in this equilibrium mixture (Schemes 4and5)l. Monoreduction ofcis‐dione9gives theendo‐alcohol25, while27is the favored product of the reductin oftrans‐dione10(Scheme 4). Optically pure (+)‐25can be prepared from (9S,10R)‐monoacetal29(Scheme 5).
(5R*, 9S*)‐ and (5R*, 9R*)‐2,2,9‐Trimethyl‐1,6‐dioxaspiro[4.4]non‐3‐ene and their Dihydro Derivatives as New Constituents of Geranium Oil
Authors: Kaiser Roman
Published: December 2004

(5 R*,9S*)‐ and (5R*,9R*)‐2,2,9‐Trimethyl‐1,6‐dioxaspiro [4.4]non‐3‐ene (1a and 1b resp.) and their dihydro derivatives 2a and 2b are described as new constituents of geranium oil. The structures and configurations of 1a, 1b, 2a, and 2b, are based on spectra interpretation and syntheses. Also some other monoterpenoid constituents identified in the same boiling range are discussed.
Synthesis of the Alleged Natural Monoterpenoid α‐Santolinenone
Authors: Guella Graizano , Cavazza Marino , Guerriero Antonio , Pietra Francesco
Published: December 2004

Authentic α‐santolinenone ( = (+)‐(4R)‐1(7)‐p‐menthen‐2‐one; (+)‐1) is made available for the the first time in 30% overall yield from (+)‐(4R)‐p‐menthene ((+)‐2) via the diastereoisomeric allylic alcohols (+)‐4a/(+)‐4b, which are oxidized to (+)‐1 with Ag2CO3/Celite. Yields are good, except for the last stage; indeed, only alcohol (+)‐4a, with equatorial OH‐group, undergoes oxidation, and (+)‐1 is partly substracted via a hetero Diels‐Alder dimerization giving a mixture of the diastereoisomeric dihydropyrans (+)‐5a/(+)‐5b. When Cr(VI) reagents ae used, (+)‐4a/(+)‐4b mainly give phellandral (6) and carvotanacetone (7), NnO2 reacts too sluggishly with (+)‐4a/(+)‐4b. A camphor pyrolyzate, previously thought to be 1 must be a different compound, probably 7.
Synthese von (S)‐Plectaniaxanthin
Authors: Dumont Raymond , Pfander Hanspeter
Published: December 2004

Synthesis of (S)‐Plectaniaxanthin

The optically active C10‐end group (S)‐5, prepared from the C5‐aldehyde (R)‐4 (ex L‐serine (2)), has been used for the synthesis of (S)‐plectaniaxanthin (1). The (R)‐chirality of natural 1 assigned by Rønneberg et al. [6] is confirmed.
New Saponins from Phytolacca dodecandra l'HERIT
Authors: Domon Bruno , Hostettmann Kurt
Published: December 2004

Three bidesmosidic saponins (1–3) have been isolated from the methanolic extract of the berries of Phytolacca dodecandra l'HERIT (Phytolaccaceae) by a combination of rotation locular counter‐current chromatography and column chromatography on reversed phase (RP‐8) With MeOH/H2O. The structures have been established by 1H‐NMR, 13C‐NMR, FAB‐MS, and D/CI‐MS, as well as on the basis of acidic and basic hydrolyses. The monodesmosidic saponins 1a–3a obtained after partial hydrolysis with a base exhibit strong molluscicidal activity against the schistosomiasis‐transmitting snail Biomphalaria glabrata. Saponins 1–3, 1a, and 3a are reported for the first time, whereas 2a has been identified previously in the aqueous extract of P. dodecandra berries.
The CAMET and CASET links for the synthesis of protected oligopeptides and oligodeoxynucleotides on solid and soluble supports
Authors: Schwyzer Robert , Felder Eduard , Merli‐Failli Paola
Published: December 2004

Simple bifunctional carboxy‐ and phospho‐protecting groups are described which allow the attachment of protected amino acids and nucleotides to soluble or insoluble carriers. After chemical synthesis with conventional procedures, the completed oligopeptides or oligonucleotides can be detached by base‐catalyzed β‐elimination, leaving other protecting groups intact. These protected biopolymer segments can then be purified, characterized, and used for further synthetic work by virtue of their free carboxy or phospho groups. It is also possible to deprotect peptides and nucleotides on the supports: this procedure may be used for the preparation of affinity‐chromatographic materials.
Fragmentation of 6‐Deoxy‐6‐halo‐hexono‐1,5‐ortholactones: A Concerted, Nonstereospecific Process
Authors: Bernet Bruno , Vasella Andrea
Published: December 2004

The synthesis of the D‐arabino‐ and D‐ribo‐ortholactones 13a–f and 15b–f and their treatment with Zn leading to the unsaturated esters 14a–d and 16a–d are described. Possible fragmentation mechanisms are discussed. The results were only compatible wit a concerted, nonsynchronous process, where both the axial lone pair of the ring oxygen atom and the lone pair formed during rupture of the C(5), O‐bond participate in the elimination of the axial and of the equatorial C(1)‐alkoxy groups, respectively.
Synthesis and Photochemistry of 2,2‐Dimethyl‐3(2H)‐thiophenone, a Ketonic Tautomer of 3‐Hydroxythiophene. Preliminary Communication
Authors: Anklam Elke , Ghaffari‐Tabrizi Ramin , Hombrecher Hermann , Lau Sabine , Margaretha Paul
Published: December 2004

On irradiation (λ = 366 nm), the 4‐thia‐2‐cyclopentenone 3a behaves in complete analogy to the oxa‐enone 3c undergoing regio‐ and stereospecific cyclodimerization, regiospecific cycloaddition with 2‐methylpropene and cycloaddition with 2,3‐dimethyl‐2‐butene to afford cyclobutane derivatives. In contrast, the 4‐aza‐2‐cyclopentenone 3b does not undergo the above‐mentioned reactions but only slow photodecomposition.
Elektromotorisches Verhalten von Flüssigmembranelektroden‐Messketten mit enantiomerenselektiven chiralen Ionophoren
Authors: Morf Werner E. , Bussmann Walter , Simon Wilhelm
Published: December 2004

Electromotive Behaviour of Liquid‐membrane Electrode Assemblies Based on Enantiomer‐selective Chiral Ionophores

A comprehensive theoretical treatment is given for the potentiometric behavior of enantiomer‐selective membrane electrodes based on chiral ionophores and plasticizers. The membrane model allows for free and complexed enantiomeric or racemic ions (e.g. ephedronium and l‐phenylethylammonium ions) as well as for achiral interfering ions. Experiments are derived for the determination of the stoichiometry and the relative stability of enantiomeric ion/enantiomeric ligand complexes, and for the analytical measurement of the enantiomeric excess of ions in solution.
An efficient synthesis of α,β‐unsaturated aldehydes by a four‐carbon unit extension of Grignard reagents
Authors: Cloux Roland , Schlosser Manfred
Published: December 2004

Copper‐catalyzed addition of organomagnesium halides to 2‐(2,2‐diethoxyethyl)oxirane (1) affords aldol acetals 2 which upon acid treatment undergo hydrolysis and dehydration to give α,β‐unsaturated aldehydes 7 with high yields.
Chemo‐ and Stereoselective Coordination of 5,6‐Dimethylidene‐7‐oxabicyclo[2.2.1]hept‐2‐ene by d8‐ and d6‐Metal Carbonyls. Diels‐Alder reactivity of Dienes Perturbed by Remote Olefin Complexation
Authors: Vioget Philippe , Bonivento Massimiliano , Roulet Raymond , Vogel Pierre
Published: December 2004

The endocyclic double bond C(2), C(3) in 5,6‐dimethylidene‐7‐oxabicyclo[2.2.1]‐hept‐2‐ene (1) can he coordinated selectively on its exo‐face before complexation of the exocyclic s‐cis‐butadiene moiety. Irradiation of Ru3(CO)12 or Os3(CO)12 in the presence of 1 gave tetracarbonyl [(1R,2R, 3S,4S)‐2,3‐η‐(5,6‐dimethylidene‐7‐oxabicyclo[2.2.1]‐hept‐2‐ene)]ruthenium (6) or ‐osmium (8). Similarly, irradiation of Cr(CO)6 or W(CO)6 in the presence of 1 gave pentacarbonyl[(1R, 2R, 3S,4S)‐2,3‐η‐(5,6‐dimethylidene‐7‐oxabicyclo[2.2.1]hept‐2‐ene)]chromium (10) or ‐tungsten (11). Irradiation of complexes 6 and 11 in the presence of 1 led to further CO substitution giving bed‐tricarbonyl‐ae‐bis[(1R,2R,3S,4S)‐2,3‐η‐(5,6‐dimethylidene‐7‐oxabicyclo[2.2.1]hept‐2‐ene)]ruthenium (7) and trans‐tetracarbonyl[(1R,2R,3S,4S)‐2,3‐η‐(5,6‐dimethylidene‐7‐oxabicyclo‐[2.2.1]hept‐2‐ene)]tungsten (12), respectively. The diosmacyclobutane derivative cis‐m̈‐[(1R,3R,3S,4S)‐(5,6‐dimethylidene‐7‐oxabicyclo[2.2.1]hepta‐2,3‐diyl)]bis(tetracarbonyl‐osmium) (Os‐Os) (9) wa also obtained. The Diels‐Alder reactivity of the exocyclic s‐cis‐butadiene moiety in complexs 7 and 8 was found to be significantly higher than that of the free triene 1.
X‐Ray and 1H‐NMR Configurational Assignment of Valofan (α‐Allphanoyl‐α‐allyl‐γ‐valerolactone) Diastereoisomers
Authors: Lauterwein Jürgen , Alan Pinkerton J. , Wittekind H. Harald , Testa Bernard
Published: December 2004

The two diastereoisomers of valofan were separated by semi‐preparative HPLC. The preferred solution conformation of the two diastereoisomer was established by 1H‐NMR spectroscopy. The spectra could be interpreted in confirgurational terms. The configuration of the more lipophilic isomer was ascertained bty X‐ray crystallography as r‐2‐allophanoyl‐2‐allyl‐t‐4‐methylbutyrolactone.
‘Lone Pair’ and ‘CI Bond’ Ionization Energies of exo‐ and endo‐2‐Norbornyl Iodides
Authors: Honegger Evi , Heilbronner Edgar , Dratva Alfred , Grob Cyril A.
Published: December 2004

A PE‐spectroscopic study of exo‐ and endo‐2‐norbornyl iodides suggests that the relative ability of the 2‐norbornyl group to stabilize an electron deficiency on a substituent X (e.g. I) in exo‐ or endo‐position depends on the location of the positive charge. There is no difference if the positive hole is strongly localized on on the substituent X (e.g. the 5p−1 state of the title compounds). On the other hand, our results indicate that teh positive hole semi‐localized in an exo‐CX bond is better stabilized by the 2‐norbornyl group than a semi‐localized, positive hole in an endo‐CX bond.
Electrochemical Synthesis of the Sex Attractant Pheromone of the Housefly: (Z)‐9‐Tricosene
Authors: Yadav Ashok K. , Tissot Paul
Published: December 2004

The electrochemical synthesis of muscalure, (Z)‐9‐tricosene(1), has been carried out by coelectrolysis of erucic acid (2) and propionic acid (3) in an undivided cell in methanol. To optimize the yield of the cross coupled product 1, the reaction has been studied in detail by varing different parameters, viz., electrode material, current density, molar ratio of 2 to 3, degree of partial neutralization and quantity of water in methanol.
γ‐Nitro‐γ‐butyrolacton
Authors: Kostova Kaline , Hesse Manfred
Published: December 2004

γ‐Nitro‐γ‐butyrolactone

By oxidation of 3‐(1‐nitro‐2‐oxocyclohexyl)propanal (1) with KMnO4, besides 3‐(1′‐nitro‐2′‐oxocyclohexyl)pripionic acid (2), the complete hydrolysis product 4‐oxononanedioic acid (4) and the oxidized semi‐hydrolysis product 5‐(2‐nitro‐5‐oxotetrahydro‐2‐furyl)pentanoic acid (3) were formed. The crystalline 3 decomposes at r.t. forming 4 and nitrous gases; its structure was established by X‐ray determination.
Synthesis, Structure, and Redox Chemistry of a Vitamin‐B12s‐Related Macrocyclic Complex of Cobalt(I)
Authors: Walder Lorenz , Rytz Gerhard , Vögeli Ulrich , Scheffold Rolf , Engel Peter
Published: December 2004

(±)‐[1‐hydro‐8H‐HDP]cobalt(I) 1

Full name of 1: [2,2,3,3,7,7,8,8,12,12,13,13,17,17,18,18,‐hexadecamethyl‐2,3,7,8,12,13,17,18,‐octahydro‐1H,23H‐10,20‐diaza‐porphinato]cobalt(I); full name of 2a: dibromo[2,2,3,3,7,7,8,8,12,12,13,13,17,17,18,18‐hexadecamethyl‐2,3,7,8,12,13,17,18‐octahydro‐1H,21H‐10,20‐diazaporphinato]cobalt(III).

For the nomenclature of [HDP]‐complexes see addendum in [2].

is obtained by chemical or electrochemical four‐electron reduction of (±)‐dibromo‐ or (±)‐dicano[1‐hydroxy‐8H‐HDP]cobalt(III) 2a or 2b4, respectively. The crystal nad molecular structure of 1 was determined by combination of X‐ray analysis and MS, 1H‐, and 13C‐NMR spectroscopy. Square‐planar coordinated Co(I) lies closely to the best plane through the four N‐atoms which form the first coordination sphere. Thermodynamic data for the coordination of axial bases with the cation of [1‐hydroxy‐8H‐HDP]cobalt 2 in its different metal oxidation states were determined. The pathway of the overall four‐electron reduction of 2a to 1 was elucidated: it involves a two‐electron reduction of the central metal, a two‐electron reduction of the macrocycle accompanied by elimination of the OH‐group and final protonation at C(1). Evidence for an intramolecular electron transfer between the central metal and the macrocycle is presented.
Komplementär diastereoselektive Cobalt‐Methylierungen des Vitamin‐B12‐Derivates «Cobester»
Authors: Kräutler Bernahard , Caderas Christian
Published: December 2004

Complementary Diastereoselective Cobalt Methylations of the Vitamin‐B12 Derivative Cobester

Treatment of heptamethyl cob(I)yrinate (2) in toluene/tetrahydrofurane (ca. 4:1) with methyl p‐toluenesulfonate under exclusion of O2 and with protection from light leads to the selective formation of the heptamethyl Coβ‐methylcob(III)yrinate (perchlorate 1b) in 75% yield. In contrast, methylation of 2 with methyl iodide under the same conditons results in the isomeric heptamethyl Coα‐methyulcob(III)yrinate (perchlorate 1a) in 73% yield, besides 7% of 1b. This complementary diastereoface‐selectivity of the methylation at the Co‐center results from alkylation under kinetic control and apparently involves two mechanistically distinct alkylation processes. A radical mechanism is considered to account for the stereochemically unusual outcome of the reaction with methyl iodide.
Bestimmung des Aggregationsgrads lithiumorganischer Verbindungen durch Kryoskopie in Tetrahydrofuran
Authors: Bauer Walter , Seebach Dieter
Published: December 2004

Degree of Aggregation of Organolithium Compounds by Means of Cryoscopy in Tetrahydrofuran

The association behaviour of alkyl‐, aryl‐ and alkinyl‐lithium compounds as well as of lithium enolates and chiral lithium azaenolates is determined from freezing‐point depression values in dilute tetrahydrofuran solutions at −108°C. Compared toX‐ray‐crystallographic data (lithiated methyldithiane, phenyllithium, lithio derivatives of a ketone, carboxylic amide and ‐ester, and a diketopiperazine‐bislactim‐ether), desaggregation is found under these conditions. The structures determined by 13C‐NMR spectroscopy for BuLi, lithiophenylacetylene and (t‐butyl)lithioacetylene are confirmed. The dilithio salt of a carboxylic acid is polymeric, a chiral lithio‐hydrazone and a chiral lithio‐oxazolidine are monomeric and dimeric, respectively. Lithium diisopropylamide is a monomer‐dimer equilibrium mixture. The apparatus described permits both synthesis and measurement of the reactive species under inert atmosphere conditions in the same vessel.
On the Nature of the 7‐Norbornadienyllithiums. Preliminary Communication
Authors: Goldstein Melvin J. , Wenzel Timothy T.
Published: December 2004

Lithium reductions of 7‐chloronorbornadiene and ofbis(7‐norbornadienyl)mercury both provide (C7H7)2Li2(5a). This product is accompanied by C7H7Li2Cl (5c) in the first case, and by C7H7Li (5b) in the second. The theoretically anticipated properties of all three organolithiums are apparent in the consistentCssymmetry of their hydrocarbon ligands, their protolytic destruction by 12‐crown‐4, and their significantJ(C(7), Li) (5a, 7.6;5b, 16.0;5c8.9 Hz).
Stabilities and Structures of Cu(II) Complexes with Linear Pentadentate Ligands by EPR Spectroscopy
Authors: Gampp Harald
Published: December 2004

The pH‐dependent equilibria between Cu(II) and the potentially pentadentate ligands 4,7,10‐triazatridecane‐1,13‐diamine (1) and 1,9bis(2‐hydroxyphenyl)‐2,5,8‐triazanonane (2) have been studied in aq. solution at 298 K by EPR titration. Each ligand forms complexes CuLHx (x=1,2,3) with strongly overlapping spectra. By using a recently developed algorithm, which does not need nay information with regard to the spectra of the species, stability constants and spectra were calculated from the EPR titration data. The anisotropic EPR spectra of the complexes were measured at 153 K and display axial or nearly axial symmetry (g∥ > g⊥) in each case. Based on the spectral parameters the assignment of the structures of the complexes was possible. With 1 and 2 the protonated complexes are equatorially coordinated, whereas in the fully deprotonated complexes an additional axial interaction occurs which is stronger with 2 than with 1.

The results of this study show that EPR spectroscopy is a useful method for investigating equilibrium systems of Cu2+ even in complicated cases where minor species occur and where the individual spectra are unknown and strongly overlapping.
Inverted Hyperconjugation in Symmetrical 1,4‐Dihalocubanes
Authors: Honegger Evi , Heilbronner Edgar , Urbanek Thomas , Martin Hans‐Dieter
Published: December 2004

The σ‐orbital manifold of cubane 1, as suggested by its PE spectrum, is divided into two sets separated by a 3 eV gap extending from ∼ ‐10.5 eV to ∼ ‐13.5 eV. Halogen substituents with np AO basis energies falling into this gap (e.g. Cl or Br) will, therefore, hyperconjugate appreciably with both sets. Interaction with the lower‐lying set will lead to the usual destabilization (‘normal’ hyperconjugation), whereas interaction with the set above will necessarily lead to a ‘stabilization’ (‘inverted’ hyperconjugation). As a result the lone‐pair ionization energies of Cl or Br substituted cubanes (derived from PE spectra) are much larger than naively expected for an alkyl halide containing as much as 8 C‐atoms. In particular no significant shift of the e lone‐pair bands in the PE spectra of 1,4‐dichloro‐ and 1,4‐dibromocubane can be detected with respect to the first ionization energies of the free atoms Cl and Br, or of HCl and HBr.
Dimerisation of caffeine
Authors: Horman Ian , Dreux Bernard
Published: December 2004

Displacements of 1H‐NMR chemical shifs for caffeine in D2O solution as a function of concentration conform to the behaviour expected for pure dimer formation according to the equilibrium 2(caffeine)⇄(caffeine)2 with a statistical probability of at least 95%. Confidence limits reported earlier for the dimerisation constant of caffeine represent the real statistical dispersion in the experimental data and do not reflect a systematic error such as tetramer formation.
Umlagerungsreaktionen von (2′‐Propinyl)cyclohexadienolen und ‐semibenzolen
Authors: Lukáč Josef , Heimgartner Heinz
Published: December 2004

Rearrangements of (2′‐Propinyl)cyclohexadienols and ‐semibenzenes

The acid‐catalyzed dienol‐benzene rearrangement of 3‐ and 5‐methyl‐substituted (2′‐propinyl)cyclohexadienols has been investigated. Treatment of the dienols with CF3COOH in CCl4 yields allenyl‐ and (2′‐propinyl)benzenes via [3,4]‐ and [1,2]‐sigmatropic rearrangements, respectively. The reaction with H2SO4 in Et2O leeds to a mixture of allenyl‐, 2′‐propinyl‐, 3′‐butinyl‐ and (2′,3′‐butadienyl)benzenes (Scheme 3). The latter are products of a thermal semibenzene‐benzene rearrangement (cf. Scheme 9). The corresponding semibenzenes have been prepared by dehydration of the cyclohexadienols with H2SO4 or POCl3 (Schemes 6 and 7). Under acidic conditions, the p‐(2′‐propinyl)semibenzenes 33–35 (Scheme 8) undergo [3,4]‐ and [1,2]‐sigmatropic rearrangements to give again allenyl‐ and (2′‐propinyl)benzenes, whereas the thermal rearrangements to the 3′‐butinyl‐ and (2′,3′‐butadienyl)benzenes (Scheme 9) involves a radical mechanism. In contrast, the o‐(2′‐propinyl)semibenzene b (Scheme 7) leads to (2′,3′‐butadienyl)benzene 32 via a thermal [3,3]‐sigmatropic rearrangement.
Synthese macrocyclischer Lactame aus Ketonen durch Ringerweiterung
Authors: Wälchli Rudolf , Bienz Stefan , Hesse Manfred
Published: December 2004

Synthesis of Macrocyclic Lactams from Ketones by Ring Enlargement Reaction

A general synthesis of N‐unsubstituted and N‐alkyllactams of general structure III is given. Starting materials for this conversion are the aldehydes of general structure I which, by reductive amination, are converted to the corresponding amines II. Under base catalysis, the ring enlargement II→III takes place (Scheme 3).
Planarisierung von tetrakoordiniertem Kohlenstoffatom. Synthese des überbrückten all‐cis‐[5.5.5.5]Fenestrans 13‐Oxapentacyclo[5.5.2.11.7.04,15.010,15] pentadecan‐14‐on
Authors: Pfenninger Armin , Roesle Alex , Keese Reinhart
Published: December 2004

Planarisation of Tetracoordinate Carbon Atom, Synthesis of the Brigded all‐cis‐[5.5.5.5]Fenestrane 13‐Oxapentacyclo[5.5.2.11,7.04,15.010,15]pentadecan‐14‐one

The synthesis of the ketolactone 23 from (Z,Z)‐1,5‐cyclooctadiene is reported. Transannular carben insertion, achieved via photolysis of the deprotonated (2,4,6‐trisisopropylphenylsulfonyl)hydrazone of 23 gives the bridged all‐cis‐[5.5.5.5]fenestrane 3.
Water Exchange on Hexaaquavanadium(III): a Variable‐Temperature and Variable‐Pressure17O‐NMR Study at 1.4 and 4.7 Tesla
Authors: Hugi Alain D. , Helm Lothar , Merbach André E.
Published: December 2004

Water exchange on hexaaquavanadium (III) has been studied as a function of temperature (255 to 413 K) and pressure (up to 250 MPa, at several temperatures) by17O‐NMR spectroscopy at 8.13 and 27.11 MHz. The samples contained V3+(0.30–1.53 m), H+(0.19–2.25 m) and17O‐enriched (10–20%) H2O. The trifluoromethanesulfonate was used as counter‐ion, and, contrary to the previously used chloride or bromide, CF3SOis shown to be non‐coordinating. The following exchange parameters were obtained:k= (5.0 ± 0.3) · 102s−1, ΔH* = (49.4 ± 0.8) kJ mol−1, ΔS* = −(28 ± 2) JK−1mol−1, ΔV* = −(8.9 ± 0.4) cm3mol−1and Δβ* = −(1.1 ± 0.3) · 10−2cm3mol−1MPa−1. They are in accord with an associative interchange mechanism,Ia. These results for H2O exchange are discussed together with the available data for complex formation reactions on hexaaquavanadium(III). A semi‐quantitative analysis of the bound H2O linewidth led to an estimation of the proportions of the different contributions to the relaxation mechanism in the coordinated site: the dipole‐dipole interaction hardly contributes to the relaxation (less than 7%); the quadrupolar relaxation, and the scalar coupling mechanism are nearly equally efficient at low temperature (∼ 273 K), but the latter becomes more important at higher temperature (75–85% contribution at 360 K).
Synthese und Reaktionen des 5‐[p‐(Dimethylamino)phenyl]‐2,2‐dimethyl‐4‐phenyl‐3‐oxazolins
Authors: Foricher Joseph , Montavon François , Pfoertner Karl‐Heinz , Schönholzer Peter
Published: December 2004

Synthesis and Reactions of 5‐[p‐(Dimethylamino)phenyl]‐2,2‐dimethyl‐4‐phenyl‐3‐oxazoline

The title compound 8 has been synthesized in a one‐pot reaction of 4′‐(dimethylamino)benzoin (4) with 2‐propanone and NH3. The preparation of the intermediate 4 from 3 is the first example of an acid‐catalyzed transformation of the stable benzoin 3 into the corresponding less stable benzoin 4. Structures and yields of various by‐products occurring under different reaction conditions during the synthesis of 8 from 4 are given. The O‐atom of the 3‐oxazoline ring in 8 could be replaced by S from P2S5 yielding the 3‐thiazoline 14. Separation of the enantiomers of the racemate 8 could only be performed by transforming them into the trimethylanilinium salts 8b and 8c of (−)‐ and (+)‐10‐camphorsulfonic acid, respectively. Solid NaOAc in boiling toluene caused the precipitation of the 10‐camphorsulfonic acids from the quaternary ammonium salts as sodium salts and the removing of the third methyl group from the quaternary ammonium salts as AcOMe to give the enantiomers (−)‐(5S)‐8 and (+)‐(5R)‐8. Their absolute configurations are deduced from an X‐ray analysis of 8b.
Propellanes. Part LXXVIII. Preparation of Several Triaza[3.3.3]propellanes and an Oxadiaza[3.3.3]propellane
Authors: Weinberg Olga , Knowles Philip , Ginsburg David
Published: December 2004

3,7,10‐Tribenzyl‐3,7,10‐triaza[3.3.3]propellane (4a), 3,7‐dibenzyl‐10‐phenyl‐3,7,10‐triaza[3.3.3]propellane (4c), 3,7‐dibenzyl‐10‐(p‐tolyl)‐3,7,10‐triaza[3.3.3]propellane (4b), and 3‐oxa‐7,10‐diaza[3.3.3]propellane (6) have been prepared.
Synthesis of the Glycopeptide Partial Sequence A80–A84 of Human Fibroblast Interferon
Authors: Kunz Horst , Waldmann Herbert
Published: December 2004

The glycopentapeptide H‐(GlcNAcβ1‐)Asn‐Glu‐Thr‐Ile‐Val‐OH (10) representing the partial sequence A80–A84 of human fibroblast interferon was synthesized using the newly developed allyl‐ester protection of carboxy functions. The allyl esters, which are stable to acids and to bases, can be cleaved under very mild, neutral conditions using tris(triphenylphosphine)rhodium(I) chloride or tetrakis(triphenylphosphine)palladium(0) as a catalyst. This synthetic method opens up a preparative route to glycopeptide model structures of glycoproteins of high biological interest.
The Structure of Pyroergotamine
Authors: Day Roberata O. , Day Victor W. , Wheeler Desmond M. S. , Stadler Paul A. , Loosli Hans‐Rudolf
Published: December 2004

The molecular structure of pyroergotamine has been determined by single‐crystal X‐ray diffraction analysis to be the pyruvoyldiketopiperazine 1. The diketopiperazine ring exists in a folded or boat conformation, with a dihedral angle of 40° between the two almost planar peptide units. The R‐group of the phenylalanine residue occupies a quasi‐axial position of the diketopiperazine ring, while that of the proline residue is in a quasi‐equatorial position. Puzzling spectroscopic and chemical properties of the compound can be rationalised in terms of crowding within the molecule.
Transamidation reactions. Part 11. N‐substituted 3‐aminopropanenitriles and 2‐aminoacetonitriles as Schiff‐base equivalents
Authors: Askitoǧlu Elefteria , Guggisberg Armin , Hesse Manfred
Published: December 2004

In presence of a strong base, the 13‐membered cyclic compound 3 yielded, by loss of acetonitrile or its equivalent, the bicyclic product 5 instead of the 17‐membered compound 4 as expected (Scheme 2). Investigation of model compounds (Scheme 4) and of model reactions (Schemes 5 and 6) led to the conclusion that the reaction proceeds via an intermediate formaldehyde imine; a Schiff base, e.g. 3b (Scheme 5), which reacts intra‐ and intermolecularly with a nucleophile to form a Mannich‐type product. It seems to be a general principle that N‐substituted 3‐aminopropanenitrile and 2‐aminoacetonitrile derivatives behave in the presence of a strong base as Schiff ‐base equivalents (Schemes 5 and 6).
Deoxy‐nitrosugars. 10th Communication. Synthesis of Isosteric Phosphonate Analogues of Ulose‐1‐Phosphates
Authors: Julina Radomir , Vasella Andrea
Published: December 2004

A general approach to isosteric phosphonate analogues of ulose‐l‐phosphates is described. A base‐catalysed chain elongation via a Michael addition of 1‐deoxy‐1‐nitro‐sugars 4, 8, and 16 to the vinylphosphonate 18 followed by hydrolysis of the nitro adducts gave the analogues of D‐ribulose‐1‐phosphate, D‐fructose‐1‐phosphate, and D‐sedoheptulose‐1,7‐diphosphate 21, 23, and 27, respectively, in high yields.
Laser Flash Photolysis of Chloranil in Solution
Authors: Guerry‐Butty Elisabeth , Haselbach Edwin , Pasquier Cécile , Suppan Paul , Phillips David
Published: December 2004

Chloranil (2,3,5,6‐tetrachloro‐2,5‐cyclohexadiene‐1,4‐dione; C) in deoxygenated acetonitrile shows transient absorptions which are assigned to the radical anion \documentclass{article}\pagestyle{empty}\begin{document}$ \rm {C}^{- \kern-4pt {.}} $\end{document} and to the triplet 3C*. The absorption due to \documentclass{article}\pagestyle{empty}\begin{document}$ \rm {C}^{- \kern-4pt {.}} $\end{document} rises ‘instantly’ during the 12 ns laser flash and then more gradually in a time of μs. This observation is explained as electron capture from neat acetonitrile by photoexcited C taking place from both its singlet and triplet states with rate constants estimated as 109 and 104 s−1 M−1, respectively.