bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesen mit Nitrilen, LXXXIV Farbe und Stereochemie von 3‐(Cyanmethylen)‐2‐indolonen
Authors: Junek Hans , Dworczak Renate , Sterk Heinz , Fabian Walter 
Published: July 2007

Abstract3‐(Dicyanmethylen)‐2‐indolone (1a–c) und 3‐[Cyan(ethoxycarbonyl)methylen]‐2‐indolone (2a–b) sind auffallend tiefrote Verbindungen. Die Farbigkeit und die Stereochemie dieser Stoffklasse werden untersucht. 1H‐ und 13C‐NMR‐Daten ergaben das Vorliegen von E,Z‐Isomeren in 2a, b, wobei durch Messung des Differenz‐NOE‐Effektes das Auftreten von trans‐s‐cis‐ und trans‐s‐trans‐Konformeren nachgewiesen werden kann. Quantenchemische Berechnungen mittels des semiempirischen AM1‐Verfahrens unterstützen diese spektroskopischen Aussagen. Mit dem INDO/S‐CI‐Verfahren werden die elektronischen Anregungsenergien von 1a, b und 2a, b berechnet und die chromophoren Eigenschaften als intramolekularer Charge‐Transfer‐Übergang diskutiert.
Enantiomerically Pure Building Blocks from Sugars, 9 An Expedient Approach to Pyranoid Ene and Enol Lactones by BF3‐Catalyzed Peroxidation of Glycal and Hydroxyglycal Esters
Authors: Lichtenthaler Frieder W. , Rönninger Stephan , Jarglis Pan 
Published: July 2007

AbstractAn effective and convenient one‐pot procedure, simply involving treatment with boron trifluoride/3‐chloroperbenzoic acid (MCPBA), is detailed for the high‐yield acquisition of enantiomerically pure dihydropyran‐2‐ones from mono‐ and disaccharide‐derived glycal and hydroxyglycal esters. An assessment of the scope of the method is given, a total of 17 examples being ample evidence for its preparative utility and apparent generality. Substantiation of the mechanism presented – BF3‐promoted removal of the allylic acyloxy group, seizure by MCPBA of the allylcarboxonium ion generated, and fragmentation of the resulting hex‐2‐enopyranose 1‐(3‐chloro)perbenzoates on quenching – is provided by characterization of the perester intermediates. Conducting the reaction of glycal esters at room temperature a glycoltype C‐1 – C‐2 bond cleavage occurs instead with the generation of acylated 4,5‐dihydroxypentenals.
Short synthesis of (±)‐4,8‐dimethyl‐1‐oxaspiro[4.5]deca‐3,7‐dien‐2‐one (andirolactone) using the propynoate/cuprate method
Authors: Krause Norbert 
Published: July 2007

AbstractRacemic 4,8‐dimethyl‐1‐oxaspiro[4.5]deca‐3,7‐dien‐2‐one (andirolactone) (1) was synthesized in two steps with 58% overall yield, starting from 4‐methyl‐3‐cyclohexenone (2) and methyl propynoate (3).
Biologically active glycosides from asteroidea, XXII. Glycosphingolipids from the starfish Astropecten latespinosus, I. Structures of three new cerebrosides, astrocerebroside A, B, and C and of related nearly homogeneous cerebrosides
Authors: Higuchi Ryuichi , Kagoshima Masahiko , Komori Tetsuya 
Published: July 2007

AbstractBy means of the high‐performance liquid chromatography (HPLC), three new cerebrosides (ceramide monohexosides), as‐trocerebroside A (8), B (10), and C (18), together with a known cerebroside, acanthacerebroside A (17), were isolated from a molecular species of cerebroside obtained from the less polar fraction of the chloroform/methanol extract of the starfish Astropecten latespinosus. On the basis of chemical and spectral evidences, their structures were determined. The structures of the nearly homogeneous cerebrosides, which appeared to be pure from HPLC and negative FAB mass spectrum, were also described.
Reaktionen der Trialkylsilyl‐trifluormethansulfonate, IX. Elektrophile Silylierung elektronenreicher Alkene
Authors: Schulz Dieter , Simchen Gerhard 
Published: July 2007

Reactions of Trialkylsilyl Trifluoromethanesulfonates, IX. — Electrophilic Silylation of Electron‐Rich AlkenesKetene O,O‐, O,S‐, and O,N‐acetals 1, 7, and 9 are converted into the C‐silylated derivatives 4, 8, and 11, respectively, by reaction with trimethylsilyl triflate (2a)/tertiary amine or sodium hydride. The ambident character of the ketene O,O‐acetals 1 in the silylation with 2a is studied.
Amphiphilic carbohydrate‐based mesogens, V. Mesogenic 1‐O‐alkyl‐D‐glucitols from alkyl D‐glucopyranosides
Authors: Dahlhoff Wilhelm V. 
Published: July 2007

AbstractThe endocyclic acetal bonds of alkyl D‐glucopyranosides (hexyl to decyl, 1a – e) are regioselectively hydroborated with ethyldiboranes(6) in the presence of 9‐methylsulfonyloxy‐9‐borabicyclo[3.3.1]nonane (MSBBN) after conversion to their 2,3,4,6‐tetra‐O‐diethylboryl derivatives 2a – e. Subsequent deboronations give the mesogenic 1‐O‐alkyl‐D‐glucitols 3a – e.
Monosaccharide mit Stickstoff im Ring, XXXIX. Synthese von modifizierten α‐L‐Fucosidase‐Inhibitoren, die 1,5‐Didesoxy‐1,5‐imino‐L‐fucit als Basisstruktur enthalten
Authors: Paulsen Hans , Matzke Michael , Orthen Bruno , Nuck Rolf , Reutter Werner 
Published: July 2007

Monosaccharides Containing Nitrogen in the Ring, XXXIX. — Synthesis of Analogues of 1,5‐Dideoxy‐1,5‐imino‐L‐fucitol, Inhibitors of α‐L‐FucosidaseVariation of the side chain in the 1,3‐dithiane derivative 1 of D‐galactose leads to a series of analogues of 1,5‐dideoxy‐1,5‐imino‐L‐fucitol (deoxyfuconojirimycin) (33), which are potent inhibitors of α‐L‐fucosidase. Cleavage of the dithioacetal in 5 followed by reduction of the aldehyde 6 and deblocking results in 1,5‐dideoxy‐1,5‐imino‐L‐galactitol (8). The aldehyde 6 is converted by Wittig reaction to 10 and 14 via 9 and 13, which are homologues of 1,5‐dideoxy‐1,5‐imino‐L‐fucitol (33). Cyclization of the Wittig product 15 yields the γ‐lactam 18. After reduction of the acetylated γ‐lactam 19 and subsequent deblocking the trihydroxyindolizidine 24 is obtained, which is an analogue of castanospermine with L‐fuco configuration. The chloride 30, which is available from 27, can be converted by intramolecular substitution and removal of the blocking groups to the bicyclic aziridine derivative (3R,4S,5R,6S) ‐1‐azabicyclo[4.1.0]heptane‐3,4,5‐triol (32). First results on the inhibitory activities of all new analogues on α‐L‐fucosidase are presented.
Natural product chemistry, 140. Synthesis of some new acridones
Authors: Reisch Johannes , Herath H. M. T. Bandara , Kumar N. Savitri 
Published: July 2007

AbstractMethyl 6‐amino‐2,3‐dimethoxybenzoate (6) which was obtained from 6‐formyl‐2,3‐dimethoxybenzoic acid (1), was treated with phloroglucinol to give two new acridone alkaloids, 1,3,8‐trihydroxy‐7‐methoxy‐9‐acridone (7) and 1,3‐dihydroxy‐7,8‐dimethoxy‐9‐acridone (8). Methylation of 7 and 8 gave another four new acridone alkaloids, 1,8‐dihydroxy‐3,7‐dimethoxy‐9‐acridone (9), 1,8‐dihydroxy‐3,7‐dimethoxy‐10‐methyl‐9‐acridone (10), 1‐hydroxy‐3,7,8‐trimethoxy‐10‐methyl‐9‐acridone (11) and 1,3,7,8‐tetramethoxy‐10‐methyl‐9‐acridone (12).
Synthesis of the α‐methyl ketoside of 5‐amino neuraminic acid methyl ester and its corresponding 5‐myristoyl and 5‐cyclopropanoyl derivative
Authors: Schrell Andreas , Whitesides George M. 
Published: July 2007

AbstractThis communication describes the first synthesis of the α‐methyl ketoside of an N‐unprotected neuraminic acid in the form of its methyl ester (Neu5NH21Me‐α‐2Me) (5a). This compound is a valuable intermediate for the synthesis of unnatural N‐substituted sialic acids. Syntheses of Neusmyristoyl1me‐α‐2Me (5b) and Neuscyclopropanoyl1me‐α‐2Me (5c) are presented.
Lascivol, der Bitterstoff des Unverschämten Ritterlings, Tricholoma lascivum (Agaricales)
Authors: Eizenhöfer Thomas , Fugmann Burkhard , Sheldrick William S. , Steffan Bert , Steglich Wolfgang 
Published: July 2007

Lascivol, the Bitter Component of Tricholoma lascivum (Agaricales)The structure of lascivol (1), the bitter principle of the toadstool Tricholoma lascivum, has been elucidated by chemical and spectroscopic studies including a single crystal X‐ray structure analysis. 1 is degraded to dimethyl L‐glutamate (6) and 5‐methoxy‐2,4‐dimethylindole (5) by acid methanolysis.
Synthese von Metallkomplexen mit Bis(phenalenyl)imin‐Liganden
Authors: Hofmann Michael , Musso Hans 
Published: July 2007

Synthesis of Metal Complexes with Bis(phenalenyl)imine LigandsSynthesis of model pigments and their metal chelates with Zn, Co, Ni, and Mn (26a–d) are described. The former are obtained from 2,4‐dihydro‐4,9‐dihydroxy‐1,2,4‐phenalenethione (14b) by connecting two molecules in a ninhydrin‐like reaction with nitrogen to the ligand 8. These models confirm the structure of the zinc complex 2 isolated from the ascomyces Roesleria hypogea. Isolation of the rearranged ester 18 proves this compound to be an intermediate in the mechanism of the degradation process of phenalenetriones 14 to acenaphthoquinones 16.
Pheromone synthesis, CXXI. Synthesis of (4R*,5R*,6S*,7E,9E)‐4,6,8‐trimethyl‐7,9‐undecadien‐5‐ol and its isomers to determine the relative stereochemistry of the female specific compound of the woodroach Cryptocercus punctulatus
Authors: Mori Kenji , Itou Masamichi , Brossut Rémy 
Published: July 2007

AbstractBy synthesizing some isomers of 4,6,8‐trimethyl‐7,9‐undeca‐dien‐5‐ol, (4R*,5R*,6S*,7E,9E)‐relative stereochemistry was assigned to the isomer isolated as the female specific compound of the tergal glands secretion of the woodroach Cryptocercus punctulatus.
Asymmetric induction of four chiral centers by hetero Diels‐Alder reaction of a chiral nitroso dienophile
Authors: Werbitzky Oleg , Klier Konrad , Felber Helena 
Published: July 2007

AbstractThe Diels‐Alder reaction of cis‐5,6‐diacetoxy‐1,3‐cyclohexadiene (1), which has a meso configuration, with the chiral nitroso dienophile 2 occurs with induction of four asymmetric centers in very high optical yield (ee = 94%) and leads to the dihydro oxazine 3 (89%). The influence of the reaction temperature on the asymmetric induction was investigated and the absolute configuration of the product determined. Reductive cleavage of the N  O bond of 3 presents a simple route to enantiomerically pure derivatives of (1R)‐conduramine A1 (82%).
Über Pyridinium‐N‐phenolat‐Betaine und ihre Verwendung zur Charakterisierung der Polarität von Lösungsmitteln, XV. Sind solvatochrome vinyloge γ‐Pyridon‐Betainfarbstoffe bessere empirische Indikatoren der Lösungsmittelpolarität?
Authors: Reichardt Christian , Milart Piotr , Schäfer Gerhard 
Published: July 2007

Pyridinium N‐Phenoxide Betaines and Their Application for the Characterization of Solvent Polarities, XV. — Are Solvatochromic Vinylogous γ‐Pyridone Betaine Dyes Better Empirical Indicators of the Solvent Polarity?The new negatively solvatochromic betaine dyes 11 and 12 are synthesized. Their solvatochromism is weaker compared with that of the standard betaine dye 1, used to introduce the ET(30) scale of solvent polarity.
Constituents of holothuroidea, II. Six newly identified biologically active triterpenoid glycoside sulfates from the sea cucumber Cucumaria echinata
Authors: Miyamoto Tomofumi , Togawa Kenichi , Higuchi Ryuichi , Komori Tetsuya , Sasaki Takuma 
Published: July 2007

AbstractFrom the whole body of sea cucumber Cucumaria echinata (Cucumariidae), we recently identified six genuine holostane‐type triterpenoid glycoside sulfates designated as cucumechinoside A (1), B (2), C (3), D (4), E (5), and F (6). The structures 1–6 were determined on the basis of chemical and spectral investigations. Antitumor activities of these cucumechinosides and their solvolized compounds (10, 11, and 12) against murine lymphoma L 1210 and human epidermoid carcinoma KB cell in vitro were examined, and their antifungal and antiprotozoal activities were also investigated.
Total synthesis of cedrusin and its methyl ether
Authors: Antus Sándor , Baitz‐Gács Eszter , Bauer Rudolf , Gottsegen Agnes , Seligmann Otto , Wagner Hildebert 
Published: July 2007

AbstractA simple synthesis of the racemates of two naturally occurring neolignans 1 and 2 was achieved starting from caffeic acid ethyl ester and the methyl ferulate 6, respectively.
Benzofuran dioxetanes, a new class of mutagenic agents: Synthesis by photooxygenation of benzofuran derivatives
Authors: Adam Waldemar , Albrecht Olaf , Feineis Erich , Reuther Irene , Saha‐Möller Chantu R. , Seufert‐Baumbach Petra , Wild Dieter 
Published: July 2007

AbstractTetraphenylporphine‐sensitized photooxygenation of benzofuran derivatives1afforded the corresponding benzofuran dioxetanes2in good yields. Allylic hydroperoxides3were formed regioselectively from 2,3‐dimethyl‐substituted benzofurans as minor products, except in the case of the benzofuran1d, which gave predominantly the hydroperoxide3d. The relative reactivities of the benzofurans toward singlet oxygen depended on the nature of substituents at the C‐2 and C‐3 positions of the furan rings. The benzofuran dioxetanes2were strongly mutagenic in the Salmonella typhimurium strain TA 100, their mutagenicity depending on the type of substituents of the dioxetane and of the benzo rings.
Antibiotics from gliding bacteria, XLIII. Phenoxan: A novel inhibitor of HIV‐1 infection in cell cultures from Polyangium sp., strain Pl VO19 (Myxobacteria)
Authors: Jansen Rolf , Kunze Brigitte , Wray Victor , Reichenbach Hans , Jurkiewicz Elke , Hunsmann Gerhard , Höfle Gerhard 
Published: July 2007

AbstractGuided by a biological screening with a cell assay, the first HIV‐1 inhibitor from a gliding bacterium, phenoxan (1), was isolated. The structure of 1 was determined by spectroscopic methods to be a substituted oxazole‐γ‐pyrone, showing a remarkable similarity to aureothin (2) and spectinabilin (3).
Synthese von 2‐Desoxy‐α‐O‐glycopeptiden mit dem N‐Iodsuccinimid‐(NIS‐) Verfahren
Authors: Kottenhahn Matthias , Kessler Horst 
Published: July 2007

Synthesis of 2‐Deoxy‐α‐O‐glycopeptides by the N‐Iodosuccinimide (NIS) ProcedureGlycosidation of amino acid/peptide derivatives of serine, threonine, or hydroxyproline with glycals like tris‐O‐acetyl‐D‐glucal 1 or tris‐O‐acetyl‐D‐galactal 2 and N‐iodosuccinimide (NIS) gives 2‐deoxy‐2‐iodo‐α‐O‐glycopeptides with high yields and excellent anomeric purity. Disaccharide glycals like per‐O‐acetyl‐D‐cellobial 15, per‐O‐acetyl‐D‐lactal 16, and 2′,3′,4′,6′‐tetra‐O‐acetyl‐β‐D‐galactopyranosyl‐(1 – 3)‐4,6‐di‐O‐benzyl‐D‐galactal 17 can also be used as glycosyl donors in this process. They give moderate to good yields of α‐O‐glycoside with formation of small amounts of β‐O‐glycopeptide. The NIS procedure is especially favored for the direct and stereoselective glycosidation of larger peptide fragments, which is very difficult with classical techniques. The so‐formed 2‐deoxy‐2‐iodo‐α‐O‐glycopeptides were deiodinated by using different methods and then deacetylated in the sugar moiety.
Epitope analysis: N4‐Formylation of the D‐benzylpenicilloyl antigenic structure
Authors: Schneider Conrad H. , De Weck Alain L. 
Published: July 2007

AbstractAcetic anhydride treatment of 6‐(benzylpenicilloylamido)‐hexanoic acid bis(benzylammonium) salt (1a) in formic acid gave the N4‐formylated derivatives 2a and 2b as diastereomeric mixtures. The inhibitory capacity of these haptens was assessed in a precipitating system involving anti‐D‐α‐benzylpenicilloyl antibody and D‐α‐benzylpenicilloyl antigen.
Antibiotics from gliding bacteria, XLIV. Ambruticins VS: New members of the antifungal ambruticin family from Sorangium cellulosum
Authors: Höfle Gerhard , Steinmetz Heinrich , Gerth Klaus , Reichenbach Hans 
Published: July 2007

AbstractA group of six new antifungal metabolites (ambruticins VS‐1 to ‐5, VS‐3 N‐oxide) was isolated from the myxobacterium Sorangium cellulosum. They were separated by RP chromatography and identified as (5S,6R)‐5‐amino‐6‐hydroxypolyangioic acids 1b–e, 2b and methyl ester 2a by spectroscopic methods.
Circular dichroism, XCV. Chiroptical properties of stereoisomeric conjugated oximes, I
Authors: Frelek Jadwiga , Huang Liang , Kerek Francis , Snatzke Günther , Szczepek Wojciech J. 
Published: July 2007

AbstractThe CD of ketoximes of defined (E)/(Z configuration and some of their O‐derivatives of steroids (4‐en‐3‐ones, 4‐en‐6‐ones, 5‐en‐7‐ones, 4,6‐dien‐3‐ones) and monoterpenoids (verbenone, carvone) have been investigated. All show two Cotton effects around 250 nm (band II) and 230 nm (band III), which usually have opposite signs. For the first‐mentioned one a rule is proposed for the correlation between CD and absolute configuration. Most of the (Z)‐oxime derivatives give an additional Cotton effect around 290 nm (band I), whose sign is always opposite to that of band II.
Photochemie von Aminoketonen, 14. Synthese und transannulare Photocyclisierung von 2‐Benzoyl‐1,4‐bis(tosyl)piperazinen
Authors: Wessig Pablo , Legart Frank , Hoffmann Berit , Henning Hans‐Georg 
Published: July 2007

Photochemistry of Amino Ketones, 141). – Synthesis and Transannular Photocyclisation of 2‐Benzoyl‐1,4‐bis‐(tosyl)piperazines1,1‐Dialkyl‐1,2‐bis(tosylamino)ethanes 4 are prepared in a three‐step reaction starting with dialkyl ketones 1. With strong bases in dimethylformamide compounds 4 react regioselectively with 1,2‐dibromoalkyl phenyl ketones 5 to afford the 2‐benzoyl‐1,4‐bis(tosyl)piperazines 6. On irradiation (≥ 300 nm) the piperazines 6a, b, f, g, without substituents in position 6, undergo Norrish‐II cleavage yielding open‐chain products. Depending on the ring conformations the 2,2‐dialkylpiperazines 6c, d, e form diazabicycloalkanes 10 and 11 on irradiation.
Darstellung und Reaktionen von N‐Phenacyl‐N‐tosylhydroxylaminen und ‐hydrazinen
Authors: Wessig Pablo , Henning Hans‐Georg 
Published: July 2007

Preparation and Reactions of N‐Phenacyl‐N‐tosylhydroxylamines and ‐hydrazinesO‐Alkyl‐N‐phenacyl‐N‐tosylhydroxylamines 3 were prepared in two steps from O‐alkylhydroxylamines 1. In the presence of a base the N‐tosylhydroxylamines 3 undergo rearrangement and cleavage to N‐tosylphenacylamine (5) and aldehydes 6. N‐Alkul‐N′‐phenacyl‐N,N′‐ditosylhydrazines 12 were obtained by stepwise treating of N,N′‐ditosylhydrazine with alkyl halide and phenacyl bromide/potassium tert‐butoxide/DMF.
Synthesis of 1 ‐[2,3‐dideoxy‐3‐(3‐hydroxypropyl)‐D‐pentofuranosyl]thymines
Authors: Walczak Krzysztof , Pupek Krzysztof , Pedersen Erik B. 
Published: July 2007

AbstractFree radicals generated by reaction of protected methyl 2,3‐ dideoxy‐3‐iodopentofuranosides 2, 3, and 9 with tributyltin hydride in the presence of a radical initiator (AIBN) were treated with acrolein to give methyl 2,3‐dideoxy‐3‐(3‐oxopropyl)pentofuranosides 4 and 5. Reduction of 5 with Sodium borohydride followed by protection of hydroxy groups by reaction with tert‐butyl chlorodiphenylsilane gave the carbohydrate derivative 11 which was condensed with silylated thymine to afford a separable mixture of α‐ and β‐nucleosides 13 and 14. These nucleosides were subsequently deprotected to give the 3′‐propyl‐extended thymidine 16 and its corresponding α‐isomer 15.
Synthese neuer optisch aktiver Kronenether
Authors: Dehmlow Eckehard V. , Knufinke Volker 
Published: July 2007

Syntheses of New Optically Active Crown EthersOptically active crown ethers 1a–1l, 2, 3a, b, 4a, b, 5a, b and the analogue 6 are synthesized. The efficiency of these compounds as phase‐transfer catalysts for a series of enantioselective reactions will be tested. This will be described in a following publication.
Efficient one‐pot approach to sugar phosphates of potential biochemical interest
Authors: Fatima Ayjaz , Zaman Fakhar , Malik Abdul , Shekhani Mohammed Saleh , Voelter Wolfgang 
Published: July 2007

AbstractEfficient one‐pot syntheses of sugar phosphates 4 – 8 are developed by way of displacement reactions of suitably protected monosaccharides with tetrabutylammonium dihydrogen phosphate and dibenzyl phosphates. This procedure is mild, convenient, and does not attack highly acid‐labile groups.
Unsymmetrically substituted furoxans, XIII. Phenylfuroxancarbaldehydes and related compounds
Authors: Gasco Andrea Marcello , Fruttero Roberta , Sorba Giovanni , Gasco Alberto 
Published: July 2007

AbstractThe synthesis and structure of the two isomeric phenylfuroxancarbaldehydes 7a and 7b, of the phenylfurazancarbaldehyde 6 and of the corresponding alcohols 3a, 3b and 5 are reported. Thermal equilibration of the furoxan derivatives and their oxidation to the corresponding carboxylic acids 8a and 8b are also discussed.
Ring Transformation Reactions, I. Conversion of 6‐Aryl‐4‐(methylthio)‐2‐oxo‐2H‐pyran‐3‐carbonitriles to pyrazoles
Authors: Ram Vishnu Ji , Verma Monika , Hussaini Falak Anwer , Shoeb Aboo 
Published: July 2007

AbstractA new ring transformation reaction has been studied by treating 6‐ or 5,6‐disubstituted 4‐(methylthio)‐2‐oxo‐2H‐pyran‐3‐carbonitriles 2 with hydrazine and methylhydrazine leading to polysubstituted pyrazoles 4, 5, 6.
Terpenes and Terpene Derivatives, XXVII. Salsolene oxide – A sesquiterpene epoxide with a new carbon skeleton
Authors: Weyerstahl Peter , Marschall Helga , Wahlburg Hans‐Christian , Kaul Vijay K. 
Published: July 2007

AbstractFrom the essential oil of Artemisia salsoloides a sesquiterpene epoxide with a new carbon skeleton, salsolene oxide (1), could be isolated. The structure and relative stereochemistry were deduced from extended NMR studies.
Addition von Nitromethan an Aldosen Untersuchung der Diastereoselektivität der Fischer‐Sowden‐Reaktion mit Hilfe der 13C‐NMR‐Spektroskopie
Authors: Köll Peter , Stenns Claudia , Seelhorst Willi , Brandenburg Heinz 
Published: July 2007

Addition of Nitromethane to Aldoses. – A Comprehensive Study of the Diastereoselectivity of the Fischer‐Sowden Reaction by the Help of 13C‐NMR Spectroscopy1)The addition of nitromethane to aldoses, commonly referred to as „Fischer‐Sowden reaction”︁, is not as stereoselective as can be concluded from the literature. This is the outcome of a comprehensive study which covered besides glyceraldehyde all aldotetroses, ‐pentoses and ‐hexoses. The ratio of the pair of diastereomeric nitroalditols has been determined in each case by 13C‐NMR spectroscopy. Thus, incidentially, a whole set of spectral data for all tetritols, pentitols, hexitols and heptitols with a terminal nitro group has been obtained, which can be correlated systematically to the respective data for the parent alditols. From these results follows that at least under conditions which give high yields of products, the reaction is thermodynamically controlled; thus, the product ratio is determined by the different energy content of the product nitroalditols (or their nitronates), which is a result of different patterns of steric interactions between substituents.
Hochsubstituierte Cyclopentadiene mit Arylthio‐ und Arylsulfonyl‐Gruppen
Authors: Hartke Klaus , Lee Kyung‐Hee , Massa Werner , Schwarz Birgit 
Published: July 2007

Highly Substituted Cyclopentadienes with Arylthio and Arylsulfonyl GroupsCyclopentadienes 1 react with diaryl disulfides 2 to form the tetrakis(arylthio)cyclopentadienides 3, which have been oxidized with m‐chloroperbenzoic acid to give the tetrakis(arylsulfonyl)cyclopentadienides 5. Protonation of 5 yields the tetrakis(arylsulfonyl)cyclopentadienes 7 by migration of arylsulfonyl groups. Oxidation of 3 by iodine leads to the dihydropentafulvalenes 11. By reaction of 3 with arylthiosulfonates 14 the pentakis(arylthio)cyclopentadienes 15 have been obtained. Their salts 16 may be oxidized to form the pentakis(arylsulfonyl)cyclopentadienides 17, or condensed with sulfenyl chlorides to give the hexakis(arylthio)cyclopentadienes 19. The structure of the phenylthio compound 19a was confirmed by an X‐ray structure analysis.
Pheromone synthesis, CXXIX. Synthesis of the (5S,9S)‐isomers of 5,9‐Dimethylheptadecane and 5,9‐dimethyloctadecane, the major and the minor components of the sex pheromone of Leucoptera malifoliella costa
Authors: Mori Kenji , Wu Jiang 
Published: July 2007

AbstractThe synthesis of (5S,9S)‐5,9‐dimethylheptadecane (1) as well as that of (5S,9S)‐5,9‐dimethyloctadecane (2) has been achieved by starting from methyl (R)‐3‐hydroxy‐2‐methylpropanoate (3a) and (S)‐citronellal (7).