bluuebunny/crossref_metadata_2025 huggingface dataset:
Organofluorine compounds and fluorinating agents, 10. Unusual regio‐ and stereoselective 3,4‐acetalizations of selected pyranosides by hexafluoroacetone as a result of a new reaction pathway
Authors: Miethchen Ralf , Rentsch Daniel , Michalik Manfred
Published: July 2007

Regio‐ and stereoselective direct acetalizations of chiral vicinal polyols with hexafluoroacetone (HFA) are described. Thus, the reaction of methyl α‐D‐mannopyranoside (1) and methyl a‐L‐rhamnopyranoside (5) with HFA affords cyclic 3, 4‐Acetals accompanied by simultaneous inversion of configuration at C‐3 when N, N′‐dicyclohexylcarbodiimide (DCC) is added as a coreagent. Methyl 2‐O‐(cyclohexylcarbamoyl)‐3, 4‐O‐(hexafluoroisopropylidene)‐a‐D‐altropyranoside (2) and methyl 6‐deoxy‐3, 4‐O‐(hexafluoroisopropylidene)‐a‐L‐altropyranoside (6), respectively, have been found to be the major products. The carbamoyl groups found in 2 and moreover in the byproduct 7 may be cleaved by methanolysis giving the Acetals 3 and 6, respectively. All of the products, 2, 3, 6, and 7 adopt a boat conformation as confirmed by NMR data and, additionally, ensured by X‐ray analysis in the case of 7. The incorrect structural formula for compound 6, reported as “methyl 2, 3‐O‐(hexafluoroisopropylidene)‐ct‐L‐rhamnopyranoside” in ref. [2], has to be corrected. The direct Acetalization described in this paper probably includes an intramolecular nucleophilic attack of a hemiacetal oxygen (4‐position) on C‐3 with substitution of an isourea function. magnified image
Unexpected triphenylphosphane‐promoted conversion of 2‐azido‐3‐vinyl‐l, 4‐naphthoquinones into 2‐amino‐3‐acyl‐l, 4‐naphthoquinones
Authors: Molina Pedro , Tárraga Alberto , Baño Maria Jose Del , Espinosa Arturo
Published: July 2007

An unusual behavior of several 2‐azido‐3‐vinyl‐l, 4‐naphtho‐quinones 1 towards triphenylphosphane leading both to azido group reduction and unsaturated carbon‐carbon side chain oxidation is described. magnified image
Lithium‐selektive Chromoionophore vom Arylazobutenoat‐Typ
Authors: Kirschke Klaus , Baumann Hendrik , Costisella Burkhard , Ramm Matthias
Published: July 2007

Lithium‐Selective Chromoionophores of Arylazobutenoate Type

New lithium‐selective chromoionophoric compounds with arylazobutenoic acid structure have been synthesized from dichlorodihydropyrazole 2. The (E,E) isomers of esters of the arylazobutenoic acid (3a, 4, 5) exhibit a remarkable color change in the presence of lithium ions and triethylamine from orange to purple. magnified image
Pheromone synthesis, CLX. A new synthesis of the oviposition‐deterring pheromone of the European cherry fruit fly Rhagoletis cerasi L.
Authors: Mori Kenji , Qian Zhao‐Hui
Published: July 2007

A new synthesis of the ammonium salt 1c of (8RS,15R)‐N‐[(β‐D‐glucopyranosyloxy)‐8‐hydroxypalmitoyl]taurine, the oviposition‐deterring pheromone of the European cherry fruit fly Rhagoletis cerasi L., was achieved by starting from 2,3,4,6‐tetra‐O‐pivaloyl‐α‐D‐glucopyranosyl bromide (2), taurine (4), ethyl (R)‐3‐hydroxybutanoate (5), propargyl alcohol (6), methyl acetoacetate (7), and 1,6‐hexanediol (8). magnified image
Naturstoffchemie, 180. Synthese von Acronycinepoxid
Authors: Reisch Johannes , Schiwek Katrin
Published: July 2007

Natural Product Chemistry, 180. – Synthesis of Acronycine Epoxide

Treatment of acronycine (1) with dimethyldioxirane in the presence of potassium carbonate resulted in acronycine epoxide (2), 1,2‐dihydro‐1,2‐dihydroxyacronycine and 5‐hydroxyacronycine (3). magnified image
Glycosyl Phosphites as Glycosyl Donors – A Comparative Study
Authors: Müller Thomas , Hummel Gerd , Schmidt Richard R.
Published: July 2007

Tri‐O‐benzyl‐L‐fucose (3) was transformed into the bis(trichloroethyl) phosphite derivative 4 which was allowed to react with 3‐O‐unprotected azidoglucose 7 as fucosyl acceptor in the presence of TMSOTf as catalyst to furnish disaccharide building block 1, useful in Lewis antigen X (LeX) synthesis, in 75% yield. Similarly, 2,3,4,6‐tetra‐O‐acetyl‐D‐galactose (8) was transformed into the bis(trichloroethyl) phosphite derivative 9 which afforded by treatment with acceptor 7 disaccharide 10 in 64% yield. The reaction of the derived acceptor 11 with donor 4 furnished trisaccharide building block 12, useful in Lewis antigen A (Lea) synthesis, in 88% yield. Transformation into the less reactive donor 14 and reaction with lactose acceptor 15 gave pentasaccharide 2 only in modest yield, thus exhibiting the scope and limitations of phosphite leaving groups in glycosylation reactions. magnified image
Synthesis of Garugamblin‐2, a Macrocyclic Diarylheptanoid Constituent of Garuga gamblei
Authors: Keserü György M. , Nógrádi Mihály , Kajtár‐Peredy Mária
Published: July 2007

The macrocyclic diarylheptanoid garugamblin‐2 (1) and its constitutional and sterical isomers 17–19 were synthesized using the isoxazole derivative 8 for the introduction of the β‐methoxyenone function. Ring closure was accomplished by an intramolecular Wittig reaction. magnified image
Anwendung des Azid‐Glycopeptidsynthese‐ Verfahrens in der multiplen Festphasensynthese zur Gewinnung von O‐Glycopeptiden des Mucin‐Typs
Authors: Paulsen Hans , Bielfeldt Tim , Peters Stefan , Meldal Morten , Bock Klaus
Published: July 2007

Application of the Azido Glycopeptide Synthesis Strategy for the Multiple Column Solid Phase Synthesis of Mucin O‐Glycopeptides

Following the strategy via azido glycopeptides the 34 O‐glycopeptides 4, 7–23 and 27–42 were synthesized in a multiple column solid phase peptide synthesis. 4, 7–23 and 27–42 are part of the repeating unit of a human intestinal mucin. The amino acids Pro and Thr in the +1 and ‐1 positions relative to the glycosylation site in 4 were exchanged by all usual amino acids. Furthermore the penta‐glycosylated octapeptide 47 was synthesized containing five vicinal 2‐acetamido‐2‐deoxy‐D‐galactosyl residues each α‐linked to Thr. magnified image
Synthese von DD‐Heptosephosphaten als Substrate oder potentielle Inhibitoren für die Heptose‐Synthetase
Authors: Paulsen Hans , Pries Meike , Lorentzen Jens Peter
Published: July 2007

Synthesis of DD‐Heptose Phosphates as Substrates or Potential Inhibitors for the Heptose Synthetase

A synthesis of D‐glycero‐D‐manno‐heptose (DD‐Hep) via an inversion of L‐glycero‐D‐manno‐heptose (LD‐Hep) is described. Starting from DD‐Hep the α‐1‐phosphate 3 and the α‐1‐methylphosphonate 30 were synthesized. Furthermore, the α‐1‐dialkyldithiophosphate esters from DD‐Hep were prepared. The 2,3,4,6, 7‐penta‐O‐benzyl‐D‐glycero‐α‐D‐ manno‐heptosyl trichloroacetimidate (22) turned out to be a very successful glycosyl donor in the reaction with the phosphate esters. The amidophosphates 41 and 42 of DD‐Hep have been synthesized according to the Staudinger reaction using glycosyl azides of DD‐Hep and tribenzyl or tributyl phosphite. The modified phosphates represent potential inhibitors for the heptose synthetase, an enzyme of the biosynthesis of the inner core region of lipopolysaccharides. Reaction of the phosphate 3 with AMP morpholidate afforded ADP‐DD‐Hep 4 which represents the product of the heptose synthetase enzyme reaction. magnified image
Synthesis of N‐Acetylneuraminic Acid Derivatives and Structural Analogues
Authors: Bodenmüller Arthur , Schmidt Richard R.
Published: July 2007

The cis‐selective Wittig reaction of D‐lyxo‐pentodialdose derivative 2 with C4 building block 3 in the presence of NaN(TMS)2 as a base furnished C9 species 4 which was transformed into ring‐opened derivative 7; diastereoselective epoxidation of the CC double bond with MCPBA afforded the required epoxide 8. Regioselective epoxide opening via trichloroacetimino derivative 9 and cleavage of the derived oxazoline 10 led to 5‐trichloroacetylamido‐substituted compound 11 having from C‐4 to C‐9 the functions and stereochemistry found for neuraminic acid. Regioselective oxidation of the 2‐hydroxy group of 1,2,4,6‐tetra‐O‐unprotected 11 with (Bu3Sn)2O/Br2 afforded directly 2‐nonulose derivative 13 which adopts the pyranose form. Compound 13 could be readily transformed into the known methyl 5‐acetylamido‐3,5‐dideoxy‐D‐glycero‐D‐galacto‐2‐nonulopyranoside (19). Regioselective Cbz protection of the 1‐hydroxy group of 13 and then treatment with MeOH/HCl furnished methyl pyranoside 22. Per‐O‐acetylation and subsequent hydrogenation liberated the primary hydroxy group at C‐1, thus providing after oxidation and esterification of the carboxylic acid moiety N‐dichloroacetylneuraminic acid derivative 25. Treatment with Bu3SnH/AIBN afforded O‐acyl protected Neu5Ac derivative 26. The structure of 26 was confirmed by an independent synthesis from Neu5Ac. magnified image
Preparation of the N‐Acetylglucosaminidase Inhibitor 1‐Acetamido‐1,2,5‐trideoxy‐2,5‐imino‐D‐glucitol from Methyl α‐D‐Mannopyranoside
Authors: Schumacher‐Wandersleb Michael H. M. G. , Petersen Stefan , Peter Martin G.
Published: July 2007

Fragmentation of methyl 3‐O‐benzyl‐6‐bromo‐2‐O‐(tert‐butyldimethylsilyl)‐6‐deoxy‐4‐O‐(4‐methoxybenzyl)‐α‐D‐mannopyranoside (2) and in situ reductive amination give (3R,4S,5R)‐6‐benzylamino‐4‐benzyloxy‐5‐(tert‐butyldimethylsilyloxy)‐3‐(4‐methoxybenzyloxy)hexene (3) which is converted by intramolecular aminomercuration into an epimeric mixture of the bromomercuriopiperidine derivatives 4 and 5. The minor D‐manno epimer 4 is transformed into mesylate 10 which, upon reaction with LiN3 in DMF, suffers a piperidine‐pyrrolidine ring contraction to give azidomethylpyrrolidine 11. Reductive acetylation by means of thioacetic acid affords the fully protected pyrrolidine aza sugar derivative 12. The major L‐gulo epimer 5 is transformed into the mesylate 15 which, again, upon reaction with LiN3 in DMF undergoes piperidine‐pyrrolidine ring contraction to give the 1‐azido‐3‐O‐benzyl‐2,5‐benzylimino‐6‐bromomercurio‐1,2,5,6‐tetradeoxy‐4‐O‐(4‐methoxybenzyl)‐L‐iditol (16). Eliminative dehalomercuration by means of Zn powder is accompanied by in situ reduction of the azido group to give amino alkene 17. Intramolecular aminomercuration of 17 followed by N‐acetylation yields the protected 1,2,5,6‐tetradeoxy‐2,5‐imino‐D‐glucitol derivative 20 as the major epimer. Reductive oxygenation of 20 leads to pyrrolidine 22 which is deprotected to give title compound 1. Selective cleavage of the PMB group of 22 leads to 24. Benzylation of 22 affords again 12 from which the OH group at C‐4 is liberated by selective cleavage of the PMB ether to give pyrrolidine 13. Compound 1 inhibits NAGase from bovine kidney. magnified image
Conformation of Deoxy Oligosaccharides: Solution Conformation and Flexibility of the Antibiotic Kijanimicin Studied by NMR Spectroscopy and MMC Calculations
Authors: Köpper Sabine
Published: July 2007

The solution conformation of the macrolide antibiotic kijanimicin (1) was deduced by a combination of NMR spectroscopy and potential energy calculations of the carbohydrate parts using the HSEA force field. The study was based on temperature dependent NMR spectroscopic shift data, 1D nuclear Overhauser enhancements (NOE) of selected protons and 2D rotating frame NOE of the complete antibiotic. NOEs in the oligosaccharide part of the antibiotic indicated some unusual short distances between the α‐linked digitoxose residues A and B, as well as between not directly linked residues A and C. Calculation of preferred conformations revealed a global minimum with ΦA,B/ΨA,B ≈ 70°/50°, ΦB,C/ΨB,C ≈ 60°/30°, and ΦB,D/ΨB,D ≈ −60°/5° for the oligosaccharide moiety. MMC simulations of the conformational flexibility indicated a high rigidity of the carbohydrate. The range of the glycosidic angles covered during MMC simulations was 50°–70° for the α‐linkages of the oligosaccharide. The ß‐glycosidic linkages of residue D and E showed slightly more flexibility, covering a range of 120° – 270°. Minimum energy calculations of the oligosaccharide part revealed a second minimum with different orientation of sugar residues A‐B and an energy difference of 2 kcal/mol to the global minimum. This energy difference increased to 12 kcal/mol when the complete antibiotic was calculated and MMC simulations did not show any transitions between the two minima. The experimental NOE in the oligosaccharide moiety and the enhancements between carbohydrate and lactone part agree well with theoretical NOEs that were obtained by sampling the global minimum in MMC simulations. The conformation of the macrolide moiety was evaluated by comparing experimental NOEs with the crystal structure of the isolated aglycon. The conformation found in solution is slightly altered around the sites of attachment of the carbohydrate parts. Constancy of the proton chemical shifts over a temperature range of 70°C indicated the high degree of rigidity of the carbohydrate moiety and most of the macrolide structure. Flexibility was observed for the C‐13/C‐20 part of the lactone ring. The antibiotic has a fairly unpolar surface and adopts a well defined and quite rigid conformation. magnified image
Chirale Lactole, XII. Untersuchungen zur basenkatalysierten Glycolaldehydaldolisierung
Authors: Noe Christian R. , Knollmüller Max , Ettmayer Peter , Freissmuth Jerome
Published: July 2007

Chiral Lactols, XII. – Studies on the Aldolization of Glycolaldehyde Catalyzed by Bases

Base‐catalyzed aldolization of the glycolaldehyde derivative 1 is studied under various reaction conditions. The resulting products, tetrose and hexose derivatives 2–11, are reduced to the corresponding sugar alcohols and analyzed by HPL chromatography. All experiments leading to a trimerization of 1 give threose 3 as major product among the tetroses and allose 4 among the hexoses. An exception is the reaction catalyzed by LiOH, in which trimerization of 1 to the corresponding hexose derivatives proceeds much slower and as products galactose 10 together with glucose 6 are favored above the other hexoses. magnified image
Synthesis and Transformation of 3‐Coumarinyl Methyl Ketone (Thio)Acylhydrazones and 5‐Substituted 3‐Acetyl‐2‐(3‐coumarinyl)‐2‐methyl‐1,3,4‐oxadiazolines under Acetylating Conditions
Authors: Somogyi László
Published: July 2007

The synthesis of 3‐acetylcoumarin (thio)acylhydrazones 1a–e and their transformation to 5‐substituted 3‐acetyl‐2‐(3‐coumarinyl)‐2‐methyl‐1,3,4‐oxa(thia)diazolines 2a–f (cyclic isomers of the alternatively accessible diacylhydrazones, e.g. 1f–h) under acetylating conditions are described. Treatment of the acetylation products 2c–f with the acetylating agent Ac2O/ZnCl2 resulted in the unexpected formation of acylhydrazones 1c, d, i with cleavage of the oxadiazoline ring and simultaneous loss of the acetyl group. magnified image
Reaction of Benzoyl(thioacetanilides) with α,β‐Unsaturated Nitriles; Synthesis of Functionalyzed Pyridines and Thiazoles
Authors: Bogdanowicz‐Szwed Krystyna , Ciechanowicz‐Rutkowska Maria , Czarny Agnieszka , Filippini Giuseppe , Pilati Tulio , Rys Barbara
Published: July 2007

The synthesis of spirofused 2‐thioxopyridines 3 from benzoyl(thioacetanilides) 1 and cyclohexylidenemalononitrile (2) is described. Cyclopentylidene‐ and cycloheptylidenemalononitrile do not react with 1. Heating of 1 in the presence of piperidine yields thiazoles 4. The structure of 4a has been established by an X‐ray analysis. magnified image
Stereoselective Synthesis of Steroids and Related Compounds, IV. Addition of Cerium Reagents Derived from (Trimethylsilyl)propargyl Bromide to Aldehydes
Authors: Eckenberg Peter , Groth Ulrich , Köhler Thomas
Published: July 2007

The addition of (trimethylsilyl)propargylmagnesium bromide (9) to aldehydes afforded predominantly the allenylic alcohols rac‐10. The regioselectivity of this addition changes dramatically when organocerium reagents were used for the addition. In this case nearly exclusive formation of the homopropargylic alcohols rac‐8 was observed. Highest selectivity for this process was obtained when cerium(III) isopropoxide (13) was used as a precursor for the formation of the organocerium reagent. magnified image
Total Synthesis of Myxovirescins, 3 Coupling of the Two Key Fragments and Last Steps to Myxovirescins A1 and M2
Authors: Maestro Miguel A. , Sefkow Michael , Seebach Dieter
Published: July 2007

The last steps of a chiral building‐block approach to the synthesis of myxovirescins A1, A2 and M2 are described. The “northwestern” parts, hydroxy sulfones (see preceding paper), and the “southeastern” parts, hydroxy aldehyde derivatives (first paper in this series), of the target molecules (Scheme 1) are first coupled by a Julia olefination (60–70% yield); the resulting linear intermediates are oxidized (CH2OH → CO2H) and deprotected for the final Yamaguchi macrolactonization (85–90% yield, Scheme 2). Deprotection by hydrolysis of three different acetal moieties and chromatographic purification gave 20‐mg amounts of synthetic myxovirescins M2 and A1 (Scheme 3) which were identical in all respects with authentic samples isolated and supplied to us by the team at the Gesellschaft für Biotechnologische Forschung in Braunschweig. – The total syntheses of the macrocyclic antibiotics consist of 62 and 66 steps, and the longest linear sequence of 25 steps was carried out in an overall yield of 2.5 and 0.85% (over 85 and 80% each step), respectively. magnified image
Iridoids from Verbascum nigrum
Authors: Vesper Thorsten , Seifert Karlheinz
Published: July 2007

In addition to the known 6‐O‐{3‐O‐[(E)‐p‐coumaroyl]‐α‐L‐rhamnopyranosyl}aucubin (2) three novel acyl iridoid diglycosides 3–5 have been isolated from the aerial parts of Verbascum nigrum. On the basis of their spectral data the structures of these iridoids have been elucidated as 6‐O‐{2‐O‐[(E)‐p‐coumaroyl]‐α‐L‐rhamnopyranosyl}aucubin (3, nigroside III), 6‐O‐{3‐O‐[(E)‐isoferuloyl]‐α‐L‐rhamnopyranosyl‐} aucubin (4, nigroside IV) and 6‐O‐{2‐O‐[(E)‐isoferuloyl]‐α‐L‐rhamnopyranosyl}aucubin (5, nigroside V). magnified image
Antibiotics from Gliding Bacteria, LIX. Disorazoles, Highly Cytotoxic Metabolites from the Sorangicin‐Producing Bacterium Sorangium Cellulosum, Strain So ce12
Authors: Jansen Rolf , Irschik Herbert , Reichenbach Hans , Wray Victor , Höfle Gerhard
Published: July 2007

Twenty‐nine disorazoles A–H (1–29) were isolated by solvent partitions and chromatographic separations from Sorangium cellulosum, strain So ce12, the producer of the sorangicin antibiotics. The disorazoles proved to be highly cytotoxic and active against fungi. The structures of the main component disorazole A1 (1) and 28 variants were elucidated by 2D‐NMR and mass spectroscopy. The disorazoles are macrocyclic dilactones of two 2‐pentadecyloxazol‐4‐carboxylic acids, which are modified in their carbon chain by variation of the position and configuration of double bonds and oxygen substituents like epoxide, hydroxyl, or methyl ether groups. In addition to these, three disorazoles are ring‐enlarged by lactonization to a more distant hydroxyl group. By feeding of 13C‐enriched precursors the biosynthetic origin of the carbons in disorazole A (1) was investigated. C‐2 of the oxazole and the attached pentadecyl chain arise from acetate. The geminal methyl groups and the methoxyl group are derived from the methyl group of methionine. magnified image
Synthesis of Sugar‐Amino Acid Conjugates via 2,3‐Dideoxy‐hex‐2‐enopyranos‐4‐uloses
Authors: Apostolopoulos Costas D. , Couladouros Elias A. , Georgiadis Minas P.
Published: July 2007

Michael addition of amino acids to 5‐substituted 2,3‐dideoxy‐hex‐2‐enopyranos‐4‐uloses 1a–c afforded stereoselectively several sugar‐amino acid conjugates in good yield. magnified image
Studies on Heterocyclic Enaminonitriles, XVI. Reactions of 2‐Benzamido‐4,5‐dihydro‐3‐thiophene‐ and ‐3‐furancarbonitriles with Cyanomethylene Compounds
Authors: Yamagata Kenji , Hashimoto Yoshichika , Yamazaki Motoyoshi
Published: July 2007

The reactions of 2‐benzamido‐4,5‐dihydro‐3‐thiophene‐ and ‐3‐furancarbonitriles (1 and 2) with ethyl or methyl cyanoacetate and malononitrile (2 equiv.) in the presence of sodium hydride (1 equiv.) in dimethyl sulfoxide at 140°C gave ethyl or methyl cyano[3‐cyano‐4,5‐dihydro‐2(3H)‐thienylidene‐ and ‐furanylidene]acetates (3a or 3b and 4a or 4b) and [3‐cyano‐4,5‐dihydro‐2(3H)‐thienylidene‐ and ‐furanylidene]propanedinitriles (3c and 4c). On the other hand, compound 2 reacted with malononitrile (2 equiv.) in the presence of sodium hydride (1 equiv.) in dimethylformamide at room temp. to give [(2‐amino‐4,5‐dihydro‐3‐furanyl)(benzamido)‐methylene]propanedinitrile (5). The same treatment of 2 with ethyl or methyl cyanoacetate followed by reaction with acetic anhydride gave ethyl or methyl 6‐acetoxy‐3‐benzamido‐2,4‐dicyano‐2‐hexenoate (6a or 6b). magnified image
Synthetic Microbial Chemistry, XXVI. Absolute Configuration of (+)‐Xanthocidin as Determined by the Synthesis of its Enantiomers of Known Stereochemistry
Authors: Mori Kenji , Horinaka Akio , Kido Masaru
Published: July 2007

The absolute configuration of the antibiotic (+)‐xanthocidin (4,5‐dihydroxy‐5‐isopropyl‐4‐methyl‐2‐methylene‐3‐oxocyclopentane‐1‐carboxylicacid, 1) was shown to be 1R,4S,5S by the synthesis of its enantiomers. Lipase AK (Amano) was used for the key resolution step, and the absolute configuration of the resolved intermediate (+)‐16 was determined by the X‐ray analysis of its (1S)‐camphanic ester (+)‐20. magnified image
Synthesis of Medium and Large Ring Compounds, XXXVII. Synthesis and Olfactory Properties of (Z)‐5,6‐Dimethylcyclododec‐5‐en‐1‐one and (Z)‐(±)‐5,6‐Dimethylcyclododec‐5‐en‐1‐ol
Authors: Kraft Philip , Tochtermann Werner
Published: July 2007

According to molecular modelling calculations the title compound 13 should fit the olfactory receptor of trans‐10‐ethyltetrahydroionol (1). In order to check this prediction the target molecule 13 and ketone 12 have been synthesized by starting from cyclooctyne and furan. Cleavage of the oxanorbornene bridge of the selectively hydrogenated Diels‐Alder adduct 5 with LTBAH/triethylborane, oxidation, epoxidation and α,β‐epoxyketone → alkynone fragmentation result in a ring enlargement of cyclooctyne by an oxotetramethylene unit. Key reaction is the diboration of cycloalkynone 9 followed by a Suzuki coupling with iodomethane. Reduction of ketone 12 gives the desired dimethylcyclododecenol 13, which possesses only a weak cedarwood note. In contrast, the corresponding ketone 12 has an intensive odor described as dry, cedar‐wood‐like with interesting cooling animal facets. magnified image
Secondary Metabolites by Chemical Screening, 28. Aspinonene, a New Multifunctional Fungal Metabolite
Authors: Fuchser Jens , Grabley Susanne , Noltemeyer Mathias , Philipps Siegrid , Thiericke Ralf , Zeeck Axel
Published: July 2007

A new C9 epoxide named aspinonene (1) was found by chemical screening in the culture broth of Aspergillus ochraceus (strain FH‐A 6692). Its structure was deduced from spectroscopic data as well as from an X‐ray analysis of the dibromobenzoate of 1. The configuration of C‐2 was further verified by esterification of the ketone 4 with chiral acids (Helmchen's method). The reactivity of the functional groups was studied by acylation, silylation, ketalization, and oxidation. Due to the diversity of its functional groups and the neighbouring centres of chirality 1 is discussed as a secondary metabolite suited as a building block for synthesis. magnified image
The Absolute Configuration of Muamvatin
Authors: Dahmann Georg , Hoffmann Reinhard W.
Published: July 2007

A degradation product 2 of muamvatin has been synthesized starting from the stereodefined building blocks 7 and 9. This synthesis allowed assignment of the absolute configuration of muamvatin as well as of the relative configuration at all stereocenters except for C‐11. The latter configuration is proposed on the basis of the 1H‐NMR data of natural muamvatin. Attempts have been made to clarify the configuration at C‐11 of muamvatin by synthesis starting from the aldehyde 9 and the ketones 28. magnified image
Reaction of 2′‐Deoxyguanosine with Glyceraldehyde
Authors: Ochs Stefan , Severin Theodor
Published: July 2007

Reaction of 2′‐deoxyguanosine with glyceraldehyde under physiological conditions leads to the formation of ammonium 2‐[9‐(2‐deoxy‐β‐D‐ribofuranosyl)‐6,9‐dihydro‐6‐oxo‐1H‐purin‐2‐ylamino]propionate (8). The same substance can be detected in 2′‐deoxyguanosine/glucose reaction mixtures as minor product. magnified image
Preparation of Diastereomeric 3,4‐O‐Pyruvate Acetal‐Containing D‐Galactopyranose Derivatives, Structural Assignment and Use for Oligosaccharide Synthesis
Authors: Ziegler Thomas , Herold Gerhard
Published: July 2007

Treatment of phenyl 1‐thio‐ and allyl 2,6‐di‐O‐benzoyl‐D‐galactopyranosides 3 with methyl pyruvate and BF3 · Et2O in various solvents gave 1,6‐anhydro‐3,4‐di‐O‐benzoyl‐2‐deoxy‐2‐phenylthio‐β‐D‐idopyranose (4) and the corresponding diastereomers of 3,4‐O‐pyruvate acetal‐containing galactosides 5. The phenyl 1‐thio‐β‐galactoside R‐5a and the allyl a‐galactoside R‐5b were both converted into methyl 3,4‐O‐[1‐(R)‐(methoxycarbonyl)ethylidene]‐β‐D‐galactopyranoside (9), the structure of which as well as that of 4 was confirmed by X‐ray crystallography. Compound R‐5a was converted into 5‐[(benzyloxycarbonyl)amino]pentyl 6‐O‐benzoyl‐3,4‐O‐[1‐(R)‐(methoxycarbonyl)ethylidene]‐β‐D‐galactopyranoside (18) by using the (2‐chloroacetoxymethyl)benzoyl (CAMB) group for the temporary protection of position 2. Glucosamination of 18 and subsequent deblocking of the intermediate disaccharide gave β‐D‐GlcpNAc‐(1→2)‐3,4‐(S)‐pyruvate‐β‐D‐Galp‐O(CH2)5NH2 (21) which represents a fragment of the Escherichia coli K 47 polysaccharide.
[(2H‐Azirin‐2‐yl)methyl]phosphonate: Darstellung aus allylischen α‐ und γ‐Hydroxyphosphonaten und Anwendung zur diastereoselektiven Synthese von substituirten [(Aziridin‐2‐yl)methyl]phosphonsäureestern
Authors: Öhler Elisabeth , Kanzler Silvia
Published: July 2007

[(2H‐Azirin‐2‐yl)methyl]phosphonates: Synthesis from Allylic α‐ and γ‐Hydroxyphosphonates and Application to Diastereoselective Formation of Substituted [(Aziriden‐2‐yl)methyl]phosphonates

Various substituted (3‐azido‐1‐alkenyl)phosphonates 3 (R3 = alkyl) or their equilibrium mixtures with the regioisomeric α‐azidophosphonates 4 (R3 = Ph) have been synthesized from allylic α‐ or γ‐hydroxyphosphonates 2 or 1 by Mitsunobu reaction with TPP/DEAD/HN3, and converted into the new [(2H‐azirin‐2yl)methyl]phosphonates 6 upon heating in toluene with DBU catalysis. The transformation 3/4→6 proceeds via base‐catalyzed rearrangement to the (3‐azido‐2‐alkenyl)‐phosphonates 5 and subsequent thermolysis. Reduction of the 2H‐azirines 6 with NaBH4 in methanol at 5°C results in the predominant formation of the disubstituted aziridines cis‐7. Addition of trimethylsilyl cyanide to compounds 6 yields stereoselectively the highly functionalized aziridines trans‐8, while NaOCH3‐catalyzed addition of dimethyl phosphite proceeds with even higher selectivity to yield the bisphosphonates trans‐9 with excellent yields.
Rubidium‐selektive Chromoionophore mit N‐(Arylazoalkenoyl)azacoronand‐Struktur
Authors: Kirschke Klaus , Baumann Hendrik , Costisella Burkhard , Ramm Matthias
Published: July 2007

Rubidium‐Selective Chromoionophores with N‐(Arylazoalkenoyl)azacoronand Structure

The N‐(arylazoalkenoyl)azacoronands 2a–2c have been synthesized by ring‐opening reaction of the dichloropyrazolin‐5(4H)‐one 1 with the corresponding azacrowns. The structure of 2a was determined by X‐ray analysis. In the presence of Rb+ salts the neutral solutions of 2a and 2b in acetonitrile or acetonitrile/water mixtures show a change of colour from yellow to red. Spectroscopic results of 1H‐, 2H‐, 13C‐ and 87Rb‐NMR investigations indicate a complexation of the Rb ion between the crown and the phenolic OH group of 2b.
Einfluß lipophiler Reste in Glucosaminderivaten auf deren Umsetzung durch Galactosyltransferase
Authors: Áts Sándor‐Csaba , Lehmann Jochen
Published: July 2007

Influence of Lipophilic N‐Acyl Derivatives of D‐Glucosamine in the Galactosylation with Galactosyltransferase

Several D‐glucosamine derivatives varying in N‐acylation were used as acceptor substrates for galactosyltransferase and the relative rates of their galactosylation by UDP‐Gal measured. One of them, 2‐deoxy‐2‐[4‐(2‐indolyl)butyramido]‐D‐glucose (6) was newly synthesised and galactosylated at a signficantly enhanced rate (14 times) in competition with GlcNAc as standard. Generally an increased lipophilicity increases the relative rate, provided the N‐acyl group in question does not sterically hinder acceptor binding because it increases the bulk of the pyranose ring system.
Contribution to the Transformations of 1‐Thioflavonoids with Hypervalent Oxidants
Authors: Somogyi László
Published: July 2007

Permanganate oxidation transforms 1‐thioflavanone (1a) to the corresponding 1,1‐dioxide 1c. Periodate oxidation of 1a affords in the cold mainly the corresponding sulfoxide 1b, and that of 1a or 1‐thioflavone 1‐oxide (2b) provides on heating 1‐thioflavone 1,1‐dioxide (2c). Since 1b is resistant to ceric ammonium nitrate (CAN) the mechanism of the dehydrogenation reaction of 1a with CAN furnishing 1‐thioflavone (2a) with transient formation of 1b, as suggested in the literature, is questionable.
Synthesis of Indeno[1,2‐b]pyrazine N‐Oxides by Reaction of Ninhydrin with 1,2‐Bishydroxylamines
Authors: Mazhukin Dmitrii G. , Tikhonov Aleksei Ya. , Volodarsky Leonid B. , Evlampieva Natal'ya P. , Vetchinov Valerii P. , Mamatyuk Victor I.
Published: July 2007

The reaction of the ninhydrin (1) with 1,2‐bishydroxylamines 2a–c affords dihydroindeno[1,2‐b]pyrazine N,N′‐dioxides 5a–c. The intermediates hexahydro‐ and tetrahydroindeno[1,2‐b]pyrazines 3a and 4c, which have been isolated, are easily transformed into 5a, c. Heating of 5b, c or keeping of 5b on alumina gives indeno[1,2‐b]pyrazine N‐oxides 6b, c, N,N′‐dioxide 7c and indeno[1,2‐b]pyrazine 8. Treatment of 5b with a solution of hydrochloric acid in H2O/MeOH leads to 6b, whereas treatment of 5b with KOH furnishes mono‐N‐oxides 6b, 9 and dioxide 7b. Compound 8 is prepared by deoxygenation of 6b with TiCl3. The reduction of 6b with NaBH4 yields alcohol 10 and the reaction of 6b with NH2OH/AcOH gives a mixture of isomeric oximes (E)‐11 and (Z)‐11.
Chemical Interactions of Thiosemicarbazides with 1,4‐Benzo‐ and 1,4‐Naphthoquinones
Authors: Hassan Alla A. , Ibrahim Yusria R. , Semida Ashraf A. , Mourad Aboul‐Fetouh E.
Published: July 2007

Thiosemicarbazones 2a–e form charge‐transfer (CT) complexes with chloranil (CHL), fluoranil (TFQ) and 2,3‐dicyano‐1,4‐naphthoquinone (DCNQ). The donors 2a–d react with 2,3‐dichloro‐5,6‐dicyano‐1,4‐benzoquinone (DDQ) to yield 3‐amino‐5‐arylthiadiazoles 7 and DDQ‐H2 (8). The thiosemicarbazide itself interacts with CHL via CT complexation to form the products 10–13. Heating of thiosemicarbazide (1) with 2,3‐dichloro‐1,4‐naphthoquinone (DCHNQ) affords the thiadiazine derivative 15.
The Reaction of Some α‐Oxygenated Cyclic Ketones with Sulfur Ylides
Authors: Marschner Christoph , Baumgartner Judith , Griengl Herfried
Published: July 2007

Cyclopentanones 1, 4 and 7, as well as uloses 11, 14, 17, and 20, all possessing an oxygen atom in α‐position with respect to the carbonyl group, have been allowed to react with dimethylsulfonium and dimethyloxosulfonium methylides. It has been found that the nucleophilic attack can be directed by the neighboring axial oxygen substituent, which leads to unusual selectivity compared to normal nucleophilic attack. The isomeric epoxides resulting from sterically directed attack have been prepared in all cases either by reaction with bromomethyllithium or by using an olefination‐epoxidation procedure.
Megastigmanes and Other Constituents of the Absolute of Boronia megastigma from Tasmania
Authors: Weyerstahl Peter , Marschall Helga , Bork Wolf‐Rainer , Rilk Rainer
Published: July 2007

Some low‐volatile constituents of the absolute of Boronia megastigma (Rutaceae) from Tasmania were isolated and characterized. Besides β‐ionone (1) and many of its derivatives, e.g. 2–7, we isolated the isomeric 3‐hydroxymegastigm‐7‐en‐9‐ones 8–10 and the megastigm‐7‐ene‐3,9‐dione (11). Furthermore, the p‐coumaric acid derivatives (E, Z)‐12 and ‐13, alkyl esters of 8‐hydroxylinalool (16a–g) and the N‐[2‐(4‐prenyloxyphenyl)ethyl]tiglamide (17) were identified.
Tetrazinodihetarene: Synthese und Eigenschaften neuer mehrstufiger Redoxsysteme vom „Weitz‐Typ”︁
Authors: Stumpf Martin , Balli Heinz
Published: July 2007

Tetrazinodihetarenes: Synthesis and Properties of New Multistep “Weitz‐Type” Redox Systems

The s‐tetrazine derivatives 3a–d and 6 were obtained by electrophilic amination of N‐heterocycles bearing a leaving group in α‐position and subsequent condensation under basic conditions. The corresponding N‐amino salts 2a–f, 5 and 7 could be isolated and characterised. Under the same conditions, it was not possible to obtain a corresponding tetrazine from 5 but the mesoionic hetarylium‐N‐imide 6 could be isolated. The structure of 11 was supported by X‐ray structure determination of its hydrogen sulfate salt. The redox potentials of the new compounds were determined by cyclovoltammetric methods. The tetrazines easily form radical salts which show unusually high stability.
A New Convenient Route for the Synthesis of DOPA Peptides
Authors: Nakonieczna Lucja , Przychodzeń Witold , Chimiak Andrzej
Published: July 2007

The tert‐butyldimethylsilyl group as the catechol protective group of DOPA (compound 1a), Boc‐DOPA (compound 1b) and DOPA esters (compounds 2a–c) is introduced. The compounds 2a–c and 1b are used as the starting substrates for the synthesis of the protected N‐terminal DOPA and C‐terminal DOPA dipeptides, 3a–d and 4a–f, respectively. Optimal conditions for deprotection are presented. Acidolysis of the fully protected DOPA peptides 3a–d and 4a–f gives quantitatively the pure DOPA dipeptides in one step.
Caffeic Acid Glycoside Esters from Gratiola officinalis L.
Authors: Rothenburger Jan , Haslinger Ernst
Published: July 2007

Two caffeic acid glycoside esters, verbascoside and arenarioside, were isolated from “hedgehyssop” Gratiola officinalis L. Their structures were determined by several one‐and twodimensional NMR experiments. After hydrolysis with 2 N hydrochloric acid and 4% sodium hydroxide solution the components were identified by GC. The absolute configuration of the monosaccharides was determined by GC separation of the diastereomers which were obtained by glycosidation with (S)‐(+)‐2‐butanol. An equilibrium between Z and E isomers was observed.
Derivate der Oxalyldimalonsäure
Authors: Stachel Hans‐Dietrich , Schorp Matthias , Maier Ludwig , Dandl Klaus
Published: July 2007

Derivatives of Oxalyldimalonic Acid

Starting with furanone 3 and mesoxalic acid esters, the compounds 8 as monolactones of the title compound have been synthesized. A versatile intermediate is the dioxinone 15, the masked acylketene 16. Regioselective partial saponification of 8a led to the diester 8e which was converted into the dilactone 2. The enamine 8d isomerizes by two pathways. By alkanolate catalysis the γ‐alkylidenetetramic acid 24 was obtained and used to prepare the lactam‐lactone 25 and the dilactam 27. Thermal isomerization of 8d gave the cyclic tetracarbonylmethane derivative 19. Ring opening reactions of 19 did not furnish derivatives of the title compound but the isomeric acids 20–23. Some open‐chain derivatives of oxalylbismalonic acid (12, 26) were obtained from 8c/8d by lactone cleavage.
Aufbau und Konformation der Hexahydro‐isochino[2,1‐b][2]benzazepine
Authors: Meise Werner , Arth Christoph , Zlotos Darius , Jansen Martin , Feldmann Claus
Published: July 2007

Synthesis and Conformation of the Hexahydro‐isoquino[2,1‐b][2]benzazepines

The synthesis of Hexahydro‐isoquino[2,1‐b][2]benzazepines 6a–c in a three‐step reaction is reported; their conformation is investigated by spectroscopic methods, X‐ray analysis and dehydrogenation with mercury(II) acetate.
Partial Synthesis of Nitrogenous Brassinosteroid Analogues with 22,26‐Epiminocholestane and Spirosolane Skeleton
Authors: Quyen Le Thi , Adam Günter , Schreiber Klaus
Published: July 2007

Starting with the known (22S,25R)‐16β‐acetoxy‐N‐acetyl‐22,26‐epiminocholest‐5‐en‐3β‐ol (4), which has been prepared from the Solanum steroid alkaloid solasodine (3), we synthesized the nitrogenous brassinosteroid analogues (22S,25R)‐2α,3α,16β‐trihydroxy‐22,26‐epimino‐5α‐cholestan‐6‐one (11), (25R)‐2α,22α‐dihydroxy‐5α,22αN‐spirosolan‐6‐one (13), (22S,25R)‐2α,3α,16β‐trihydroxy‐22,26‐epimino‐6,7‐seco‐5α‐cholestano‐6,7‐lactone (15), and (25R)‐2α‐3α‐dihydroxy‐6,7‐seco‐5α,22αN‐spirosolano‐6,7‐lactone (18) as well as some of their derivatives.
Synthesis of (3R)‐3‐Hydroxy‐2‐Hexanone, (2R,3R)‐2,3‐hexanediol and (2S,3R)‐2,3‐hexanediol, the Male Sex Pheromone of Hylotrupes bajulus and Pyrrhidium sanguineum (cerambycidae)
Authors: Schröder Frank , Fettköther Regina , Noldt Uwe , Dettner Konrad , König Wilfried A. , Francke Wittko
Published: July 2007

The following compounds were identified as male pheromone components of the longhorn beetles Hylotrupes bajulus and Pyrrhidium sanguineum: (3R)‐3‐hydroxy‐2‐hexanone [(3R)‐1], (2S,3R)‐2,3‐hexanediol [(2S,3R)‐4] and (2R,3R)‐2,3‐hexanediol [(2R,3R)‐4]. The syntheses of enantiomerically pure samples, enantiomeric separation by chiral gas chromatography and unambiguous structure assignment of the target compounds are described.
Synthesis and Biological Activity of a Potent Renin Inhibitor of the Azapeptide Type
Authors: Gante Joachim , Krug Michael , Lauterbach Günter , Weitzel Reinhard
Published: July 2007

A highly potent renin inhibitor of the azapeptide type (2) is synthesized by starting from the hydrazine derivative 3. This peptide analogue inhibits renin in the same range (nanomolar) as its purely peptidic original 2a, but reveals much higher specificity for renin than 2a does.
ENSO history recorded in Agathis australis (kauri) tree rings. Part B: 423 years of ENSO robustness
Authors: Fowler A. M.
Published: July 2007

Part A of this study identified the potential of kauri tree rings for reconstructing the history of past ENSO activity. Plausible indices of multidecadal to centennial‐scale ENSO activity (phase dominance and robustness) that could be derived from kauri regional master chronologies are hypothesized here, and they are tested against the instrumental SOI record, using partitioning and graphical analyses. The subset of the indices passing this first screening are then tested for sensitivity to the complex evolving sample depth and site‐composition mix that characterizes regional tree‐ring chronologies. Corrections for evolving sample depth are developed where possible. The two indices of ENSO activity remaining after these two screening phases (evolving chronology time‐series variance and decadal‐scale spectral signature) are used to infer 423 years of ENSO robustness and the results are compared to two multiproxy ENSO reconstructions. Results suggest that ENSO robustness (1) peaked in the 20th century, (2) is characterized by persistent 55–80 year cyclicity, (3) was low in the mid‐20th century only relative to robust ENSO activity at the beginning and end of that century, (4) reached a pre‐20th century peak in the mid‐18th century, and (5) was weakest near the beginning of the 19th century. Copyright © 2007 Royal Meteorological Society
Analysis of large‐scale conditions associated with convection over the Indian monsoon region
Authors: Roy Bhowmik S. K. , Sen Roy Soma , Kundu P. K.
Published: July 2007

This paper examines the thermodynamics of the atmosphere in relation to occurrence of convective rainfall over the Indian region. Various thermodynamical and kinematic parameters such as convective available potential energy (CAPE), convective inhibition energy (CINE), equivalent potential temperature and relative vorticity field are computed based on model analysis field of the limited area model of India Meteorological Department. The data period of this study is from 15 March 2001 to 28 February 2002. The study shows that the spatial distribution of CAPE in pre‐monsoon and monsoon season exhibits a belt of high CAPE along the east coast extending north up to Gangetic West Bengal and another zone of high CAPE along the southwest coast. During post‐monsoon and winter seasons, the belt of maximum CAPE shifts over the extreme southern Peninsula. The annual variation of CAPE over all stations is bi‐modal in nature with twin peaks each at the beginning and at the end of the monsoon season. Magnitude of CINE on the other hand is nearly zero during the monsoon season. The result shows that presence of strong thermodynamic environment is not sufficient for the occurrence of deep convection. Factors like proper dynamic conditions play a very important role in controlling the occurrence of deep convection. The surface warming during the pre‐monsoon season destabilizes the atmosphere, but large‐scale moist convection, generally, does not take place until CINE becomes close to zero (in the monsoon season). Preceding the monsoon season, the land sea contrast heating strengthens circulation in the lower atmosphere, which in turn leads to the moistening and destabilization of lapse rate. This process starts about a month prior to the actual start of the monsoon rainfall, allowing moisture to build up to lead to the widespread monsoon rainfall. During winter months, rainfall occurs over northwest India in association with high negative value of CINE and over southern Peninsula in association with high value of CAPE. Substantial changes are noticed in the equivalent potential temperature (θe) and vorticity profiles between days with and without rainfall over northwest India (Delhi). The results suggest that the increase in moisture in association with the occurrence of rainfall over Delhi is of advective origin. Where as, other regions (Kolkata, Mumbai and Thiruvananthapuram) display relatively smaller changes in the vertical profiles of θe, indicating an in situ presence of moisture. Copyright © 2007 Royal Meteorological Society
Study of erythemal, UV (A + B) and global solar radiation in Valencia (Spain)
Authors: Cañada J. , Esteve A. R. , Marín M. J. , Utrillas M. P. , Tena F. , Martínez‐Lozano J. A.
Published: July 2007

Although ultraviolet B radiation (UVB), the solar radiation band between 280 and 315 nm, is only a small fraction of the extraterrestrial solar radiation, it accounts for 80% of the harmful effects of exposure to the sun. In this work values of erythemal solar irradiance (UVER) measured in Valencia on a horizontal plane in the period between June 2003 and June 2005 are analysed and compared with measures of UV (A + B) and global irradiances on a horizontal plane. UV erythemal (UVER) irradiance has been measured using a YES‐UVB‐1 broadband radiometer; UV (A + B) irradiance has been measured using a TUVR Eppley radiometer with spectral response between 290 and 385 nm and global irradiance on a horizontal plane has been measured with a Kipp and Zonen model CM‐6 broadband radiometer. A study of a statistically representative index of UVER irradiance has been made by comparing with the results corresponding to UV (A + B) irradiance and those of global irradiance on a horizontal plane. A fit has been performed using all the irradiance values to estimate the UVER and UV (A + B) components as functions of the other ranges. We have calculated for each month the irradiation acumulated during an average day, for the UVER, UV (A + B) and global, the highest values was 4.1, 791 and 25 146 kJ/m2 respectively. Copyright © 2007 Royal Meteorological Society
Cyclicity analysis of precipitation regimes in the Yangtze River basin, China
Authors: Becker S. , Hartmann H. , Zhang Q. , Wu Y. , Jiang T.
Published: July 2007

Daily precipitation data of 148 weather stations located in the Yangtze River basin (P.R. China) are analysed to detect cycles in the annual frequency of occurrence of precipitation events of 1‐, 5‐ and 10 days duration. These events were defined in terms of exceedances of some selected thresholds. The events corresponding to 10, 25 and 30 mm thresholds for 1‐, 5‐ and 10‐day precipitation totals, respectively, are analysed in detail. For the identification of cycles, basin‐wide averaged standardized time series of frequency of precipitation events are used. It is found that peaks in the smoothed time series occurred around 1974, 1982 and 1991. The Fourier, autoregressive and wavelet analyses reveal distinct cycles of 7–9 and 2–3 year periods, which dominate large parts of the time series. In addition, a shift towards a 4–5 year period in the annual frequency of precipitation events is noticed since the mid‐ to late‐nineties. Major peaks in the annual frequency of occurrence of precipitation events are expected to occur around 2012, 2015 and 2018 according to the spectrum analyses. Copyright © 2007 Royal Meteorological Society
Solamargine upregulation of Fas, downregulation of HER2, and enhancement of cytotoxicity using epirubicin in NSCLC cells
Authors: Liang Chia‐Hua , Shiu Li‐Yen , Chang Li‐Ching , Sheu Hamm‐Ming , Kuo Kou‐Wha
Published: July 2007

Nonsmall‐cell lung cancer (NSCLC) is not generally a chemosensitive tumor, and the mechanism of resistance to the relevant anticancer drugs has not been fully elucidated. Solamargine (SM), the major steroidal glycoalkaloids extracted from the Chinese herb Solanum, inhibits the growth of human tumor cells. We have previously demonstrated that SM regulates tumor necrosis factor receptors (TNFRs)‐ and mitochondria‐mediated pathways and sensitizes NSCLC cells to initiate apoptosis. Interestingly, this investigation reveals that SM up‐regulated Fas expression and down‐regulated the expression of HER2, whose overexpression is associated with resistance to drugs, and promotes chemotherapy‐induced apoptosis in NSCLC A549 and H441 cells. After treatment with SM, the expression of HER2 mRNA was correlated with the expression of topoisomerase IIα (TOP2A) mRNA. The combinatory use of low concentrations of SM with low‐toxic topoisomerase II inhibitor epirubicin accelerated apoptotic cell death. Therefore, the downregulation of the HER2 and TOP2A expression by SM with epirubicin may partially explain the SM and epirubicin cytotoxicity synergy effect in NSCLC. Results of this study suggest that SM induces Fas and TNFR‐induced NSCLC cell apoptosis and reduces HER2 expression. These findings provide the synergistic therapeutic interaction between SM and epirubicin, suggesting that such combinations may be effectively exploited in future human cancer clinical trials.
The prediction of 1H chemical shifts in amines: a semiempirical and ab initio investigation
Authors: Basso Ernani A. , Gauze Gisele F. , Abraham Raymond J.
Published: July 2007

Twenty one conformationally fixed amines and their N,N‐dimethyl derivatives were obtained commercially or synthesized. These included cis and trans 4‐t‐butyl cyclohexylamine, 2‐exo and 2‐endo norbornylamine, 2‐adamantylamine, 4‐phenylpiperidine, 1‐napthylamine and tetrahydro‐1‐napthylamine. The 1H NMR spectra of these amines were measured in CDCl3 solution, assigned and the 1H chemical shifts given. This data was used to investigate the effect of the amino group on the 1H chemical shifts in these molecules. These effects were analyzed using the CHARGE model. This calculates the electric field and steric effects of the amino group for protons more than three bonds removed, together with functions for the calculation of two‐bond and three‐bond effects. The rotational isomerism about the CN bond of the amino group was investigated by ab initio calculations of the potential energy surface (PES) about this bond at the HF/3–21G level. The resulting conformers were then minimized at the B3LYP/6‐311 + + G (d,p) level. These geometries were then used to calculate the 1H chemical shifts in the above compounds by CHARGE and the ab initio gauge‐invariant atomic orbital (GIAO) method at the B3LYP/6–311 + + G(d,p) level and the shifts were compared with those observed. The compounds investigated gave 170 1H chemical shifts ranging from 0.60 to 8.2 ppm. The rms errors (obs.—calc.) were ca 0.1 ppm (CHARGE) and ca 0.2 ppm (GIAO). Large deviations of ca 1.0 ppm were observed for the NH protons in the GIAO calculations. The complex spectra of alkyl and aryl amines can thus be successfully predicted by both ab initio and semiempirical methods except for the NH protons, for which the ab initio calculations are not sufficiently accurate. Copyright © 2007 John Wiley & Sons, Ltd.