bluuebunny/crossref_metadata_2025 huggingface dataset:
Preparation and Characterization of Oligo‐(2,2′‐Bipyridyl)pyrazines
Authors: Heirtzler Fenton R. , Neuburger Markus , Zehnder Margareta , Constable Edwin C.
Published: July 2007

An improved preparation of 2,2′‐bipyridine‐6‐carboxaldehyde 1 provides this compound in good yield for the further syntheses of oligo‐(2,2′‐bipyridyl)pyrazines 6–8, new ligands for supramolecular metallorganic complexes. According to 1H‐NMR spectroscopic and X‐ray crystallographic studies, the bis(2,2′‐bipyridyl) compound 6 exists in a helical conformation in solution and in the solid state. The structure of the tetrakis(2,2′‐bipyridyl) compound 8 is also confirmed through its crystal structure.
Synthesis and In Vitro Antitumor Activity of 2′‐Deoxy‐5‐fluorouridylyl‐(3′→5′)‐2′‐deoxy‐5‐fluoro‐N4‐octadecylcytidine: A New Amphiphilic Dinucleoside Phosphate
Authors: Schott Herbert , Ludwig Peter S. , Gansauge Frank , Gansauge Susanne , Schwendener Reto A.
Published: July 2007

The new amphiphilic dinucleoside phosphate, 2′‐deoxy‐5‐fluorouridylyl‐(3′→5′)‐2′‐deoxy‐5‐fluoro‐N4‐octadecylcytidine (4) was synthesized on a gram scale, using the phosphotriester method, starting from the cytostatic drug 2′‐deoxy‐5‐fluorouridine (5FdU) and 2′‐deoxy‐5‐fluoro‐N4‐octadecylcytidine (1d). In in vitro clonogenic growth assays using the human pancreatic adenocarcinoma cell line MIA PaCa 2, the amphiphilic dimer was significantly more effective than the parent monomeric 5FdU. The IC50 of the dimer was 10 μg/ml when applied as an aqueous solution and 12 μg/ml when given as a liposome dispersion, whereas with 5FdU the IC50 concentration was not reached within the concentration range used.
Michael Addition versus 1,3‐Cycloaddition Reactions of Pyridinium Ylides with (Arylmethylene)isoxazol‐5‐ones: Diastereoselective Formation of 4‐[1‐Aryl‐2‐(1‐pyridinio)ethyl]isoxazolium‐5‐olates
Authors: Risitano Francesco , Grassi Giovanni , Bruno Giuseppe , Nicolò Francesco
Published: July 2007

The reactions of (arylmethylene)isoxazol‐5‐ones 1 with pyridinium ylides 2 lead to the diastereoselective formation of olates 4. The reasons for the favored Michael addition and the unsuccessful subsequent cyclization to fused O‐heterocycles are discussed on the basis of X‐ray analysis as well as 1H‐NMR and chemical evidences.
Asymmetric Synthesis of (R,S)‐Dehydroiridodial, (R,S)‐Dehydroiridodiol and Analogues
Authors: Enders Dieter , Kaiser Anja
Published: July 2007

The synthesis of (R,S)‐(–)‐dehydroiridodiol(dial) [(R,S)‐6b], isolated from the plant Actinidia polygama Miq., and its analogues, in high diastereo‐ and enantiomeric purity (ee ⩾ 96%) is described. Key steps of the synthesis are the Michael addition of metallated SAMP hydrazones [(S)‐1] to the 2‐cyclopentenecarboxylate 2 and subsequent conversion to the 5‐substituted 2‐methylcyclopentenecarboxylates 5.
Cycloadditions, 55. – Substituent Effects in Tandem Intramolecular Silyl Nitronate Olefin Cycloadditions (ISOC) Leading to Functionalized Tetrahydrofurans
Authors: Hassner Alfred , Friedman Oded , Dehaen Wim
Published: July 2007

The intramolecular silyl nitronate olefin cycloaddition (ISOC) leading to substituted, fused‐ring tetrahydrofurans 6 was examined with regard to optimum conditions and substituent effects. The required unsaturated nitro ethers 3 resulted from low‐temperature, base‐mediated Michael addition of allyl alcohols 2 to nitroolefins 1, followed by conversion to unsaturated silyl nitronates 4. Cycloaddition of the latter and elimination of silanol provided 6. One‐pot tandem reactions, starting with nitroolefins 1 and allyl alcohols 2 and involving four steps, sometimes proceeded in better yields but often gave unexpected side products. Terminal olefinic electron‐donating substituents (Me, MeO) increased the rate of cycloaddition, while an internal olefinic methyl substituent slowed down the reaction. In the case of nitronates possessing ester or nitrile moieties as terminal olefin substituents, tandem Michael addition to produce substituted furans 14, 15 occurred faster than trapping of the nitronate anion by TMSCI.
Synthesis of Carbon‐Backbone‐Elongated GDP‐L‐Fucose Derivatives as Substrates for Fucosyltransferase‐Catalysed Reactions
Authors: Vogel Christian , Bergemann Claudia , Ott Andrej‐Jakob , Lindhorst Thisbe K. , Thiem Joachim , Dahlhoff Wilhelm V. , Hällgren Christer , Palcic Monica M. , Hindsgaul Ole
Published: July 2007

Starting from the 6‐O‐tert‐butyldimethysilyl‐2,3;4,5‐di‐O‐isopropylidene‐D‐galactose diethyl dithioacetal (4) and proceeding through a Wittig reaction and Swern oxidation, a series of L‐fucose analogues, which unlike the normal L‐fucose possess an extended alkyl‐chain at C‐5, can be produced. The elongated carbon backbone in the L‐fucitols (22–25) as well as in the L‐fucose derivatives (30–33) increases the hydrophobic nature of the sugar molecule, promoting liquid‐crystalline properties in both series. The further derivatization of the L‐fucose analogues 30, 31 leads to the corresponding β‐L‐galacto‐deco‐ and dodeco‐pyranosyl phosphates 46, 47 and, in turn, to the respective pyranosyl guanosine 5‐diphosphates 48, 49. The reaction of the β‐L‐galactopyranosyl guanosine 5‐diphosphate 48 with 8‐methoxycarbonyloctyl 2‐acetamido‐2‐deoxy‐4‐O‐(β‐D‐galactopyranosyl)‐β‐D‐glucopyranoside (50) in the presence of a 3/4‐α‐fucosyltransferase furnished an O‐glycosidic linkage of the α‐L‐galactopdecopyranose 30 at the 3‐O‐position of the N‐acetyllactosamine glycoside 50. The chemo‐enzymatic coupling reaction proves that the synthesized carbon‐backbone‐elongated L‐galactopyranosyl guanosine 5‐diphosphates are suitable substrates for the α‐fucosyltransferases.
Allenyl Enolates – A New Class of Chiral Ambident Nucleophiles, 5. Ireland–Claisen Rearrangements of Allenic Silyl Ketene Acetals
Authors: Becker Markus , Krause Norbert
Published: July 2007

Allenic silyl ketene acetals 3 formed by conjugate 1,6‐addition of organocuprates to 2‐propen‐1‐yl and 2‐buten‐1‐yl 2‐en‐4‐ynoates 1 and regioselective enolate capture with silyl electrophiles readily undergo [3,3]‐Ireland‐Claisen rearrangements to the 2‐substituted methyl 3,4‐dienoates 4. The simple diastereoselection of the formation of 4b could be improved by variation of the silylating agent as well as the addition of bases. in the case of product 4c, the sigmatropic rearrangement also takes place with good diastereofacial selectivity, i.e., with axis‐to‐center chirality transfer.
Chemistry of Aziridine Carboxylic Acids, 7. Synthesis of Ethyl (2R,3S)‐N‐Boc‐ and ‐N‐Benzyl‐3‐vinylaziridine‐2‐carboxylates: New Potential Building Blocks for Enantiomerically Pure Unsaturated Amino Acids
Authors: Jähnisch Klaus
Published: July 2007

Enantiomerically pure cis‐ and trans‐1H‐aziridine‐carboxylic acid derivatives 2a, b and 3a, b have been prepared by asymmetric Michael‐type addition of ammonia to chiral acrylates 1a, b with high syn selectivity. The title compounds were obtained from the diols 8a, b by Corey‐Winter olefination.
Recent Advances in N‐Protection for Amino Sugar Synthesis
Authors: Debenham John , Rodebaugh Robert , Fraser‐Reid Bertram
Published: July 2007

Recent synthetic efforts in the construction of oligosaccharides, glycoproteins, glycolipids and other glycoconjugates containing a variety of 2‐amino‐2‐deoxy sugars have led to the development of new methods for nitrogen protection. These new nitrogen‐protecting groups have been removed from substrates using mild and often chemoselective conditions. In this microreview, the preparation, present uses, and deprotection of amino sugar derivatives employing these new agents are described. Applications of phthalimides with electron‐withdrawing groups including the tetrachlorophthaloyl (TCP), dichlorophthaloyl (DCPhth), dithiasuccinoyl (Dts), N‐pent‐4‐enoyl and N,N‐diacetyl functionalities are discussed.
Pheromone Synthesis, CLXXIX. Synthesis of Lurlenic Acid and Lurlenol, the Sex Pheromones of the Green Flagellate Chlamydomonas
Authors: Takanashi Shin‐Ichi , Mori Kenji
Published: July 2007

Lurlenic acid {(4E,8E,12E)‐14‐[2′‐hydroxy‐3′,4′‐dimethyl‐5′(1″‐β‐D‐xylopyranosyloxy)phenyl]‐4,8,12‐trimethyltetradeca‐4,8,12‐trienoic acid (1)} and lurlenol (2), the sex pheromones produced by the female gametes of the green flagellate Chlamydomonas, were synthesized by starting from D‐xylose, 2,3‐dimethyl‐p‐hydroquinone and geranylgeraniol or farnesol. Synthetic 1 and 2 were biologically active, while the possible biogenetic precursor 3 was inactive.
Positional and Facial Selectivity in Diels‐Alder Reactions of (−)‐(aS,7S)‐Colchicine: Synthesis of Novel Analogues of the Alkaloid
Authors: Brecht René , Haenel Frank , Seitz Gunther , Frenzen Gerlinde , Pilz Astrid , Massa Werner , Wocadlo Sigrid
Published: July 2007

Positional and facial selectivity in Diels‐Alder reactions of several hetero‐ and carbodienophiles with (−)‐(aS,7S)‐colchicine (1) has been examined. In all cases, cycloaddition occurred with high positional selectivity at the 8,12‐positions of the alkaloid and preferentially from the diene facesynto the allylic substituent at the stereogenic center C‐7. The observed high π‐facial diastereoselectivity is independent of the polarity of the solvent used and is therefore probably a consequence of steric factors. The structures of the Diels Alder‐adducts of1with singlet oxygen,N‐phenyl‐1,2,4‐triazolinedione (PTAD) andtrans‐cyclooctene,4,5, and15, respectively, were assigned on the basis of spectral data and verified by X‐ray crystallography.
Photoreactions of trans‐10b,10c‐Dimethyl‐10b,10c‐dihydropyrenes
Authors: Cerfontain Hans , Koeberg‐Telder Ankie , Bakker Bert H. , Mitchell Reginald H. , Tashiro Masashi
Published: July 2007

The photoisomerization of trans‐10b,10c‐dimethyl‐10b,10c‐dihydropyrene (1), its 2,7‐di‐tert‐butyl derivative 5 and a series of potassium sulfonate derivatives of 1, in both [D8]1,4‐dioxane and [D2]dichloromethane as solvent, has been studied using λ = 420–570 nm irradiation. Irradiation of a deoxygenated solution of 1 in dioxane leads to the exclusive formation of anti‐8,16‐dimethyl[2.2]metacyclophane‐1,9‐diene (2), whereas the photoconversion of 1 in a non‐degassed solution leads to the successive formation of 2 and 5,8‐epidioxy‐anti‐8,16‐dimethyl[2.2]metacyclophane‐1,9‐diene (7). Similarly, irradiation of the 2,7‐di‐tert‐butyl derivative 5 in oxygen containing [D8]dioxane as solvent leads to the consecutive formation of the corresponding 5,13‐di‐tert‐butyl derivatives 6 and 8. Irradiation of mixtures of potassium sulfonate derivatives of 1 (1‐Sn) in D2O as solvent leads to photoisomerization with formation of the correspondingly substituted sulfonate derivatives of 2. Only with the dipotassium 2,4‐ and 2,5‐disulfonates of 1 eventually small amounts of the corresponding epidioxy‐bridged products 7 were formed. The photoisomerization 1‐Sn → 2‐Sn appeared to be most effective for 1‐2‐S and 1‐2,5‐S2 and least effective for 1‐2,4,7‐S3 and 1‐2,4,7,10‐S4. In the dark, the epidioxy products 7 and 8 reverted to give initially the corresponding metacyclophanes 2 and 6, and subsequently the respective dihydropyrenes 1 and 5, and the dark reactions of the potassium sulfonate derivatives 2‐Sn yielded the correspondingly substituted 1‐Sn. A quantitative study showed that the dark reactions steps 7 → 2, 8 → 6, and 2‐Sn → 1‐Sn (n = 1–4) exhibit first‐order kinetics. For the deoxygenation of 5,8‐epidioxy‐anti‐8,16‐di‐methyl[2.2]metacyclophane‐1,9‐diene (7) the rate coefficient is ca. 2.7 times that of its 5,13‐di‐tert‐butyl derivative (8), and the rate coefficient for the isomerization 2‐Sn → 1‐Sn follows the order 2‐5‐S → 2‐5,13‐S2 > 2‐1,5,10‐S3.
An Efficient Procedure for the Preparation of 3‐Acetyl‐2,3‐dihydrobenzo‐thiazoles by Ring Contraction of 2,4‐Diaryl‐2,3‐dihydro‐1,5‐benzothiazepines under Acetylating Conditions
Authors: Tóth Gábor , Lévai Albert , Balázs Barbara , Simon András
Published: July 2007

Reaction of 2,4‐diaryl‐2,3‐dihydro‐1,5‐benzothiazepines 1 with a mixture of acetic anhydride and pyridine afforded 3‐acetyl‐2,3‐dihydrobenzothiazoles 2 as sole products in good yields. Stereochemistry and the hindered rotation of the amide group were studied by means of NMR spectroscopy and the results were corroborated by AM1 calculations. A reaction mechanism for the ring contraction is proposed.
Demethyl(trifluoromethyl)actinomycins, II. Bis(trifluoromethylated) 4‐(2′‐Benzoxazolyl)actinocin Derivatives
Authors: Bahner Isabel , Lackner Helmut
Published: July 2007

In a previous study, performed in connection with the total synthesis of trifluoromethylated actinocinyl peptides 2a, the oxidative condensation of the corresponding o‐aminophenol precursor 1 furnished a novel trimerisation product, which had been tentatively assigned to the triphenedioxazine structure 3[1]. Now, an improved synthesis of the trimer and extensive 1‐ and 2D‐NMR studies have resulted in a new, quite unexpected structure: the 4‐(2′‐benzoxazolyl)actinocin derivative 8a, which replaces 3. Apparently, the quinone‐sided CF3 group of an actinocin intermediate is unusually activated and reacts with a third o‐aminophenol unit. The modifications to the synthesis increase the overall yield of demethyl‐(trifluoromethyl)actinomycins by a factor of five.
New Synthesis of 28‐Homobrassinolide from Stigmasterol
Authors: Hazra Braja G. , Kumar Tirunahari Pavan , Joshi Padmakar L.
Published: July 2007

An efficient and short synthesis of 28‐homobrassinolide (6) has been achieved in 12 steps with 15.6% overall yield from stigmasterol (8). Salient features of this synthesis are: (a) use of tetradecyltrimethylammonium permanganate for chemoselective cis‐dihydroxylation of the 2,22E‐dien‐6‐one 9, avoiding the use of OsO4; (b) one‐step epoxidation of the (22E)‐olefin and Baeyer‐Villiger oxidation of the B‐ring ketone 11 with trifluoroperoxyacetic acid; and (c) regioselective ring‐opening of the 22,23‐epoxide 12 to the bromohydrin 13 with LiBr and Amberlyst‐15 resin under mild conditions and in excellent yield.
Asymmetric Synthesis of Primary Amines by Nucleophilic Addition of Alkyllithium Compounds to Aldehyde SAMP/RAMP Hydrazones
Authors: Enders Dieter , Nübling Christoph , Schubert Heinrich
Published: July 2007

The aldehydes 1 or 5 are converted to the SAMP hydrazones 2 or the α‐alkylated SAMP hydrazones 7 and treated with organolithium compounds at low temperature. Cleavage of the NN bond of the resulting hydrazines 3 and 8 with Raney‐Ni/H2, or of the N‐methoxycarbonylhydrazines 9 with Li/NH3, yield the amines 4 with 61–90% ee, the amines 11 with 45–96% de and 93 → 99% ee. The absolute configuration of the amines 11 was established by X‐ray analysis of an appropriate MTPA derivative.
High Regioselectivity in Polar Additions to 1,6‐Diazacyclodeca‐3,8‐diynes
Authors: Ritter Joachim , Gleiter Rolf
Published: July 2007

The reactions of 1,6‐dialkyl‐1,6‐diazacyclodeca‐3,8‐diynes (9, a = CH3, b = C2H5, c = i‐C3H7) with HCl, H2O and CH3OH have been investigated. The reaction of 9c with HCl selectively gives N,N′‐diisopropyl‐4‐chloro‐1,2,3,5,6,7‐hexahydro‐2,6‐naphthyridine (13c) in quantitative yield. Investigation of this reaction at different temperatures allows the activation parameters for the process to be derived (ΔH≠ = 24 ± 1 kcal · mol−1, ΔS≠ = – 9 ± 2 cal · mol−1 · K−1). The regioselective reaction of 9c with methanol affords a quantitative yield of N,N′‐diisopropyl‐4‐methoxy‐1,2,3,4,5,6,7‐hexahydro‐2,6‐naphthyridine (29c). Addition of water to 9a in the presence of H2SO4 gives N,N‐dimethyl‐7‐oxo‐1,2,3,4,5,6,7,8‐octahydro‐2,6‐naphthyridine (28a) in low yields (15%). If the addition of water is carried out in the presence of Hg2+, the yield of 28a is increased considerably. The mechanisms of all three reactions are discussed and those involving electrophilic addition (AdE2) are favored.
Reactions of α,β‐Enones with Diazo Compounds, 2. Synthesis of Dihydrofuran Derivatives
Authors: Anac Olcay , Daut Ayse
Published: July 2007

Several α,β‐unsaturated ketones were treated with dimethyl diazomalonate and ethyl acetodiazoacetate under bis(acetyl‐acetonato)copper(II) catalysis. Dihydrofuran derivatives, obviously arising from carbonyl ylides, were isolated in high yields. Structural identifications were carried out using 2D‐NMR‐spectroscopic data.
Properties and Reactions of Substituted 1,2‐Thiazetidine 1,1‐Dioxides: 3‐Acetoxy‐1,2‐thiazetidine 1,1‐Dioxide, Synthesis and Reactions with C‐Nucleophiles
Authors: Schwenkkraus Peter , Merkle Stefan , Otto Hans‐Hartwig
Published: July 2007

N‐Silylated 3‐acetoxy‐1,2‐thiazetidine 1,1‐dioxide (5) is prepared from L‐cystine. Reactions of 5 with silyl enol ethers yield C‐3‐substituted β‐sultams 6, 12 and 15. Desilylation of 6 affords 7, which undergoes photochemical cyclization to give the bicyclic β‐sultam 10. In the course of such reactions, a portion of the C‐3‐substituted β‐sultam is consumed in a retro‐Michael‐type reaction, leading to the open‐chained sulfonamides 8 and 13 as side products. In the case of reactions between 5 and silyl enol ethers of cyclic ketones 16, only such open‐chained products, 17, are isolated. Reactions of 5 with substituted malonates yield the β‐sultams 19 and 20. Structures and stereochemistry are elucidated by spectroscopic methods.
Enantiospecific Synthesis of 2,5‐Disubstituted Piperidine Derivatives: Synthesis of (+)‐Pseudoconhydrine
Authors: Dockner Michael , Sasaki N. André , Riche Claude , Potier Pierre
Published: July 2007

A novel methodology for the synthesis of any one of the four stereoisomers of a 2,5‐disubstituted piperidine in optically pure form is described, starting from readily available chiral building blocks 10 and 11 (or their antipodes). The utility of this approach is demonstrated in the total synthesis of (+)‐pseudoconhydrine hydrochloride, the structure of which was confirmed by X‐ray analysis.
The Wittig and Related Reactions in Natural Product Synthesis
Authors: Nicolaou K. C. , Härter Michael W. , Gunzner Janet L. , Nadin Alan
Published: July 2007

Originally reported in Liebigs Annalen in 1953 (then called Justus Liebigs Annalen der Chemie), the Wittig reaction has evolved to include the Horner–Wittig and Horner–Wadsworth–Emmons reactions and several other variations. Today, these reactions constitute some of the most powerful processes for the construction of carbon–carbon bond frameworks, facilitating the chemical synthesis of myriads of organic molecules both in research laboratories and industrial settings. The Wittig and related reactions were proven particularly useful in the field of total synthesis, where they enabled the construction of highly complex structures and had a significant impact in shaping the art to its present state of sophistication. In this article the authors focus, after a brief introduction, on total syntheses from their own laboratories that employ such processes. These examples, together with the numerous others adorning the chemical literature, illustrate amply the importance of the Wittig and related reactions and point to their continuing prominence in organic synthesis.
1‐Methylgeraniol as Novel Regio‐ and Diastereoselective Probe for Hydrogen Bonding in Hydroxy‐Assisted Oxygen‐Transfer Reactions
Authors: Adam Waldemar , Mitchell Catherine M. , Paredes Rodrigo , Smerz Alexander K. , Veloza L. Angela
Published: July 2007

The chiral 1‐methylgeraniol has been designed and applied for epoxidation reactions as a mechanistic probe, which allows to assess simultaneously in one and the same molecule regio‐ and stereochemical information. Of the two trisubstituted double bonds, the terminal 7,8 one reflects kinetic preferences on account of its greater π nucleophilicity, the 3,4 one with the chiral allylic hydroxy functionality expresses diastereoselective directivity through hydrogen bonding. The combination of regio‐ and stereoselectivity provides a novel and powerful mechanistic tool to differentiate electronic and steric effects of oxidants. Thus, various epoxidizing agents have been employed and the mechanistic implications derived from the product ratios are well in line with those reported, which exemplifies the validity of the probe.
Synthesis of rac‐Midpacamide and the spiro‐Cyclization of Its Precursor
Authors: Lindel Thomas , Hoffmann Holger
Published: July 2007

The alkylidene hydantoin 8 was synthesized as an analogue of the marine natural product oroidin (1) by employing a Horner‐Wadsworth‐Emmons reaction. Treatment of 8 with bromine in acetic acid induced a biomimetic spiro‐cyclization forming the ACD ring system of dibromophakellin (2) in one step. rac‐Midpacamide (10) was obtained from the same precursor through a chemoselective, ruthenium‐catalyzed hydrogenation leaving the brominated pyrrole moiety intact.
trans‐ and cis‐Bicyclo[n.1.0]alk‐2‐ynes of Medium Ring Size
Authors: Detert Heiner , Meier Herbert
Published: July 2007

Starting from cycloalkenes, the cis‐ or trans‐cyclopropano anellated cycloalkynes 2–7 of medium ring size were synthesized. The triple bonds were introduced in the final reaction step either by the fragmentation of the corresponding 1,2,3‐selenadiazoles or by direct dehydration of a ketone (Scheme 2). The cis‐fused bicycles 2 and 3 and the trans‐fused bicycles 5, 6 and 7 could be isolated in a pure state. The intermediary existence of the most strained system trans‐bicyclo[7.1.0]dec‐2‐yne (4) was proven by trapping reactions.
Unsaturated Hetero Chains, VI. ω‐alkoxy‐ and ω‐Amino‐Substituted Oligonitriles – Synthesis, Structures, and Reactivity
Authors: Aust Nicola C. , Fröhlich Roland , Hecht Jürgen , Würthwein Ernst‐Ulrich
Published: July 2007

ω‐Alkoxy‐substituted 1‐oxa‐3,5‐diazahexatrienes (5), 1‐oxa‐3,5,7‐triazaoctatetraenes (7), and 1‐oxa‐3,5,7,9‐tetraazadecapentaenes (9) were synthesized by condensation of 1,3‐dialkoxy‐2‐azapropenylium salts (3) or 1,5‐dialkoxy‐2,4‐diazapentadienylium salts (8) withN‐acyl‐ andN‐alkoxycarbonylamidines (4). It is the nature of the leaving group which mainly determines the chain length of the products obtained. – Compounds7show ring‐chain tautomerism involving the cyclic form6in dependence of the substitution pattern. All ω‐alkoxy substituted oligontriles5, 7and9may easily converted to the corresponding ω‐amino compounds11, 14, and15by reaction with secondary amines10. Reaction of5a, bwith the primary amine12leads to the triazinone13. The lithiated ketimine16converts5band7dto the corresponding 1‐oxa‐3,5,7‐triazaoctatetraenes17and 1‐oxa‐3,5,7,9‐tetraazadecapentaenes18. Helical geometries dominate the structures of the new oligonitriles in the crystalline state as derived from X‐ray analyses of compounds5a, 7c, 9a, and18. Push‐pull substitution effects, which should be strong in the amino derivatives11, 14, and15, have no significant influence on the structure of the oligonitriles.
A Butyrolactone → 1,3‐diol Strategy for the Obtention of Tolypothrix Polyethers – Total Synthesis of the Tolypothrix Pentaether from Enantiomerically Enriched S‐Glycidol
Authors: Priepke Henning , Brückner Reinhard
Published: July 2007

Permethyl ether 1 from Tolypothrix conglutinata was synthesized following the retrosynthetic analysis of Scheme 1. According to it, we combined aldehyde 3 [prepared from S‐glycidol (7); cf. Schemes 2, 3] and lactone 4 (also prepared from S‐glycidol (7); cf. the preceding communication[2] and Scheme 4) to the enantiopure and diastereopure trimethoxy lactone 2 (Scheme 5). The CO group of this lactone was removed through the Criegee rearrangement of a derived lactol peroxonosylate (Scheme 6); thereby, the CCO bond of lactone 2 was replaced with complete retention of configuration by one COH bond of the resulting syn‐configured diol 18. Protecting group manipulations (Schemes 6, 7) and oxidation of the resulting alcohol 21 to aldehyde 31 (Scheme 10) initiated the three final operations: C2‐homologation with Ph3PCH‐CHO (→ enal 32), tosyl hydrazone formation (→ 34), and reduction/concomitant CC bond migration. They led to the target ether 1 as a 89:11 mixture with the CHCH‐richer ether 36.
An Unorthodox Pathway to the 1,2‐Dithiin System
Authors: Huisgen Rolf , Kalwinsh Ivars , Morán Joaquín R. , Nöth Heinrich , Rapp Jochen
Published: July 2007

Tetracyanoethylene combines with two molecules of thiobenzophenone in refluxing benzene to give the tetrasubstituted 1,2‐dithiin 8 (21–29%) besides the corresponding thiophene derivative 9 (40–52%). The X‐ray analysis of the ruby‐red 8 reveals a half‐chair conformation with a torsion angle of 58.9° at the disulfide bond. The thermal desulfurization 8 → 9 (benzonitrile, 100°C) proceeds with t1/2 = 26.7 h, whereas the sulfur loss induced by triethyl phosphite is a billion times faster. The mechanisms of the formation of 8 and its sulfur extrusion are discussed in the light or recent literature.
1,3‐Dipolar Cycloadditions, 99. Nitrones and Thiones: Cycloadditions and Surprising Metathesis Reactions
Authors: Giera Henry , Huisgen Rolf
Published: July 2007

Nitrone 4 combines with alicyclic thioketones at room temp. affording 1,4,2‐oxathiazolidines. Steric hindrance in both reactants affects the cycloaddition/cycloreversion equilibria, but the mobility is still high; the low π‐LUMO energies of CS are responsible for the superdipolarophilic character. Nitrone 4 and thiobenzophenone enter into a metathesis reaction which was traced back to a sulfhydrogenolysis pathway; H2S acts as a catalyst. An analogous metathesis between nitrone 4 and benzaldehyde involves a hydrolysis.
Antibiotics from Gliding Bacteria, LXXX. Chivosazoles A–F: Novel Antifungal and Cytotoxic Macrolides from Sorangium cellulosum (myxobacteria)
Authors: Jansen Rolf , Irschik Herbert , Reichenbach Hans , Höfle Gerhard
Published: July 2007

The myxobacterial metabolites chivosazole A (1) and its variants (2–6) were discovered in Sorangium cellulosum, strain So ce12, which simultaneously provides the broad spectrum antibiotic sorangicin as well as the sorangiolides and disorazoles. The antifungal and cytotoxic chivosazoles (1–6) are novel glycosides of 6‐deoxyglucopyranose derivatives and an aglycon that includes an oxazole in its 31‐membered macrolide ring. The aglycon itself, chivosazole F (7), was formed by strain So ce885 and showed similar activity antibiotic and cytotoxic.

The biogenetic origin of the structural elements in chivosazole F (7) was studied by feeding experiments with [1‐13C]‐, [1,2‐13C]acetate, [methyl‐13C]methionine and [1‐13C]serine. Accordingly, the aglycon 7 is a polyketide assembled by condensation of nine acetate units, one serine unit and a further seven acetate units. While C‐1 of serine is part of the macrolide ring, the amido to hydroxyl part of the serine together with C‐1 of the adjacent N‐acetyl unit form the 1,3‐oxazole ring. C‐ and O‐methyl groups are derived from methionine.
An Attempted Synthesis of 2,6‐Bis(phenylazo)barbaralane
Authors: Quast Helmut , Becker Christian , Peters Eva‐Maria , Peters Karl , von Schnering Hans Georg
Published: July 2007

Treatment of the unsaturated ketone 6 with phenylhydrazine fails to afford the unsaturated phenylhydrazone 3 but gives the tricyclic phenylhydrazoketone exo‐8, which is oxidised with iron(III) chloride to yield the phenylazoketone exo‐9. The configuration of exo‐9 is elucidated with the help of an X‐ray diffraction analysis. The unsaturated phenylazo compound 14 is obtained from Meerwein's diketone 10 in two ways. Iodination of the phenylhydrazone 11 in the presence of pyridine followed by elimination of pyridinium iodide from the bispyridinium salt 13 with aqueous sodium hydroxide in dimethyl sulphoxide furnishes 14 in low yield. A somewhat better yield is more conveniently achieved when the dibromodiketones exo,exo‐ and exo,endo‐12 are allowed to react with phenylhydrazine in the presence of pyridine. Bromination of 14 with N‐bromosuccinimide in cyclohexane as solvent affords the labile dibromide 15. Both reagents employed, viz. the zinc/copper couple in refluxing tetrahydrofuran and butyllithium at low temperature, fail to convert 15 into the hoped‐for bis(phenylazo)barbaralane 1 but instead give rise to the formation of the isomer 17, either by cyclisation of the intermediate anion 16 or by rearrangement of 1.
Cycloallenes, 11. 1‐Phenyl‐1,2‐cyclononadiene: Preparation and Dimerisation
Authors: Christl Manfred , Moigno Damien , Peters Eva‐Maria , Peters Karl , Von Schnering Hans Georg
Published: July 2007

1‐Phenyl‐1,2‐cyclononadiene (10) was prepared by addition of dibromocarbene to 1‐phenylcyclooctene and treatment of the resulting 9,9‐dibromobicyclo[6.1.0]nonane 7 with methyllithium. In addition to 10, the 9‐bromo‐9‐methylbicyclononanes cis‐ and trans‐8 as well as the bicyclopropylidene 9 were formed. The dimerisation of 10 proceeded slowly already at room temperature and gave rise to the 1,2‐bismethylenecyclobutane derivatives cis‐ and trans‐11. From the complex mixture that resulted on thermolysis at 200°C of cis‐ and trans‐11 only their isomer 12 could be isolated. Heating of a benzene solution of tetracyanoethylene and cis‐ and trans‐11 afforded the Diels‐Alder adduct 13 of cis‐11, which rearranged to the benzodicyclononene derivative 14 on thermolysis.
New Biphenylenophanes and Biphenylophanes – 1,8‐Dimethylbiphenylene by Continuous Vacuum Pyrolysis
Authors: Laufenberg Susanne , Feuerbacher Nina , Pischel Ivo , Börsch Oliver , Nieger Martin , Vögtle Fritz
Published: July 2007

The synthesis of 1,8‐disubstituted biphenylenes by pyrolysis of azo compounds has been optimized. By means of a continuously working pyrolysis apparatus, the cis isomer 2 can be reliably produced on a gram scale. The chiral syn‐[2.2]biphenylenophane 12 has been synthesized by an intermolecular cyclization reaction, subsequent oxidation of the sulfur atoms and pyrolytic extrusion of sulfur dioxide. In an analogous manner, the [2.2]biphenylophane 13 was obtained. The separation of the racemates of the hydrocarbons 12 and 13 could be achieved using a stationary chiral HPLC phase. Compound 12 preferentially adopts a syn conformation in the solid state. The CD spectra of 12 and 13 are compared.
Photochemistry of 11,12‐bis(Aminomethyl)‐9,10‐dihydro‐9,10‐ethenoanthracene in Solution and in the Solid State
Authors: Scheffer John R. , Ihmels Heiko
Published: July 2007

The photochemistry of 11,12‐bis(aminomethyl)‐9,10‐dihydro‐9,10‐ethenoanthracene (4) was investigated in solution and in the solid state. Direct irradiation of 4 gave the singlet state photoproduct 5, whereas the triplet derived photoproduct could only be obtained by irradiating the bis(hydrochloride) salt of 4 in the presence of xanthen‐9‐one to give semibullvalene 6‐(HCl)2. Solid state photolysis of 4 resulted in the formation of the pyrrole derivative 7, which is likely due to steric interactions in the solid state.
A Convenient Synthesis of γ,δ‐Unsaturated N‐Formylenamines by Wittig Alkenylation of γ,δ‐Unsaturated Diformamides
Authors: van Vliet Michiel C. A. , Meuzelaar Gerrit J. , Bras Jérǒme , Maat Leendert , Sheldon Roger A.
Published: July 2007

γ,δ‐Unsaturated N‐formylenamines (5–7) were prepared in two steps from readily available γ,δ‐unsaturated alcohols. The alcohols were converted into the γ,δ‐unsaturated diformamides (N,N‐diformylamines, 1–4) by tosylation, followed by reaction with sodium diformamide. The γ,δ‐unsaturated diformamides were applied in a Wittig reaction under mild conditions to give the title compounds with a conjugated enamide group in moderate to high yields.
Special Calixarenes by Directed Syntheses
Authors: Böhmer Volker
Published: July 2007

The synthesis of special calixarenes and calixarene‐like macrocyclic compounds via stepwise procedures and fragment condensation is reviewed. Among the compounds available are exo‐ and endo‐calixarenes consisting of different phenolic units, having bridges other than methylene or showing inherent chirality (Cn‐symmetry). Macrobi‐ and ‐tricyclic molecules such as bridged calixarenes, double calixarenes, bicyclocalixarenes and annelated calixarenes are also described. Single crystal X‐ray structures are reported for several compounds. Some properties like conformational barriers, pKa values or the ability to complex metal ions are discussed, showing the potential of these compounds which may (only) be produced by directed synthesis.
Bimolecular Formation of Radicals by Hydrogen Transfer, 13. Uncatalyzed Transfer Hydrogenation of Azulene and the Initiation of the Azulene‐Naphthalene Rearrangement
Authors: Keller Friedrich , Beckhaus Hans‐Dieter , Rüchardt Christoph
Published: July 2007

From the uncatalyzed transfer‐hydrogenation of azulene 1 with the hydrogen donors 9,10‐dihydroanthracene (4), 7H‐benz[de]anthracene (5) and 9,9‐diphenyl‐10,10‐dideuteroanthracene (6) at 340–375°C in diphenyl ether, two isomeric octahydroazulenes and, in addition, naphthalene and tetralin are obtained. From product studies, kinetics, isotopic labelling experiments and semiempirical MO calculations, a nonchain stepwise radical mechanism is proposed, which is initiated by H‐atom transfer from the donor to azulene. The proposed mechanism for the formation of naphthalene and tetralin via azulene‐naphthalene rearrangement under these conditions is a combination of the Scott mechanism and the Alder “walk” mechanism, which are initiated by the hydrogen‐transfer step.
Electrosynthesis of α‐Aminonitriles: Anodic Cyanation of N‐Substituted Tetrahydroquinolines and N‐Phenylpiperidines
Authors: Le Gall Erwan , Hurvois Jean‐Pierre , Renaud Tristan , Moinet Claude , Tallec André , Uriac Philippe , Sinbandhit Sourisak , Toupet Loic
Published: July 2007

The electrochemical cyanation of N‐alkyl‐substituted cyclic six‐membered amines including N‐alkyl‐1,2,3,4‐tetrahydroquinoline and N‐phenylpiperidine derivatives has been investigated. The reaction gives the corresponding α‐aminonitriles and was carried out at a graphite felt anode percolated with a methanolic solution of the amine, containing six equivalents of sodium cyanide per mol of substrate, and lithium acetate as the supporting electrolyte. In the case of N‐substituted tetrahydroquinolines 1a–f, cyanation occurs regioselectively at the ring and the position of substitution depends on the nature of the N‐alkyl substituent. The stereoselectivity of the cyanide addition was investigated using various 3‐methyltetrahydroquinolines 8a–c as substrates. In all cases, the major stereoisomers 9a–c possess a cis configuration in which the 2‐cyano group has an axial disposition and the 3‐methyl group is equatorial. In a similar fashion, various N‐phenylpiperidines substituted at the ring by either one or two methyl groups were oxidized. In all the selected amines the introduction of the cyanide group occurs stereospecifically in the position α to the nitrogen atom. The cis or trans relative configuration of the cyanated compounds is discussed separately for each substrate. It is noteworthy that in all cases the cyano group was in an axial position.
Product Analysis in the Iodine(III)‐Promoted Oxidation of Carbohydrate‐Derived Cyclic Enol Ethers: A Mechanistic Study
Authors: Harders Jan , Garming Alfons , Jung Alexander , Kaiser Volker , Monenschein Holger , Ries Monika , Rose Lars , Schöning Kai‐Uwe , Weber Thomas , Kirschning Andreas
Published: July 2007

A study on the mechanism of the well‐documented hypervalent iodine‐mediated allylic oxidation of glycals leading to 2,3‐dihydro‐4H‐pyran‐4‐ones is presented. Notable features are the isolation of ring‐contracted by‐products 6 and 7, which are produced upon oxidation of per‐O‐benzylated glycal 4, as well as the characterization of carbohydrate‐derived tetrahydrofurfurals 12a and 13a, which are formed by the conformation‐dependent oxidation of glycals 9a and 10b. In addition, the iodine(III)‐mediated oxidation process has been studied by in situ NMR spectroscopy of lyxo‐configured glycals 14a,b. Intermediate alkylphenyliodonium species 19b,d and 2‐enoyranosides 16a and 20a have been characterized by their NMR signals. These data support a plausible mechanism that is initiated by electrophilic attack of the iodine(III) reagent on the electron‐rich enol ether double bond of the glycal. This is followed by the breaking of a bond β,γ‐positioned in relation to the carbohydrate‐bound iodine and subsequent reductive elimination of iodobenzene. Thus, depending on the glycals employed, a number of diverse oxidation products may be formed.
A Practical Synthesis of 3‐Methoxyflavones
Authors: Deng Bo‐Liang , Lepoivre Jozef Arsène , Lemière Guy , Dommisse Roger , Claeys Magda , Boers Frank , De Groot Alex
Published: July 2007

Some 3‐methoxyflavones were known to possess antipicornavirus properties. In order to study the structure‐activity relationship, attempts to prepare 3‐methoxyflavone by literature methods were unsuccessful. We have modified the Baker‐Venkataraman rearrangement, using a solid base and a phase‐transfer catalyst. After searching optimal reaction conditions and a study of the intermediate formed in a model reaction, good yields were obtained for the 3‐methoxyflavones 7, 21–32. Further some of the corresponding 7‐O‐n‐butyl derivatives 4, 33–37 could be isolated as side products.
Vinylogous β‐Carotenes: Generation, Storage, and Delocalization of Charge in Carotenoids
Authors: Broszeit Guido , Diepenbrock Felix , Gräf Oliver , Hecht Dirk , Heinze Jürgen , Martin Hans‐Dieter , Mayer Bernhard , Schaper Klaus , Smie Andreas , Strehblow Hans‐Hennig
Published: July 2007

In this paper, we report on the synthesis of β‐carotenes of variable chain length with between 5 and 23 double bonds (1–7). These oligoenes were prepared by McMurry and Wittig reactions. The tetradecapreno‐β‐carotene 7 would seem to be the longest β‐carotene yet reported. Furthermore, we investigated the electronic properties using cyclic voltammetry and photoelectron spectroscopy (UPS) to generate open‐shell and closed‐shell ions of carotenoids in solution and in the solid state, respectively. With increasing chain length (⩾ 11 double bonds), even the generation of tetracations and tetraanions could be observed by cyclic voltammetry. Extending the number of conjugated bonds causes the potentials to converge to limiting values. All electron‐transfer processes occur in one‐electron steps, which are close to each other in pairs. The potential difference between the first oxidation potential and the first reduction potential is a linear function of the reciprocal chain length. Despite the different techniques used (CV and UPS) and the different condensed phases, there is an excellent correspondence between the energies of the radical cation states generated by the two methods. This shows that the radical cation formation is principally determined by the chain length. The structures of the ion states were investigated using semiempirical methods at the NDDO level. Charge delocalization and bond relaxation are not identical and do not utilize the same number or the same kind of atoms. It can be shown that from the length of 20 double bonds onwards, the effective conjugation length for doubly‐charged cations converges slowly to a limiting value.
Mukaiyama Reactions of a Silyl Enol Ether with Heteroatom‐Substituted β‐Formyl Esters
Authors: Angert Hubert , Czerwonka Regina , Reißig Hans‐Ulrich
Published: July 2007

Heteroatom‐substituted aldehydes 3, 4, and 5 were subjected to Mukaiyama reactions with silyl enol ether 10. The reaction of the new trifluoromethyl‐substituted aldehyde 3 with 10 afforded γ‐lactone 11 with excellent trans selectivity. In contrast, the known benzyloxy‐substituted aldehyde 4 and 10 provided γ‐lactone 13 without any selectively in the presence of BF3 as the promoting Lewis acid; use of TiCl4 induced exclusive cis selectivity. Carbamoyl‐substituted aldehyde 5 and silyl enol ether 10 were combined under different conditions, although good diastereoselectivity could not be achieved. The results obtained are discussed in terms of the electronic effects of the substituents and their ability to form chelates.
Electrochemical Oxidation of 4‐Ethenyl[22]paracyclophane: Cyclic Voltammetry, Electrosynthesis of Polymers, Analysis by Liquid Chromatography, and Mass Spectrometry
Authors: Gollas Bernhard , Hesse Ingrid , Lotz Ralf , Pasch Harald , Speiser Bernd , Zagos Ioannis
Published: July 2007

4‐Ethenyl[22]paracyclophane is oxidized electrochemically at a platinum electrode in acetonitrile/0.1 M tetra‐n‐butylammonium hexafluorophosphate. Its behavior in electro‐oxidation is compared to that of styrene. Cyclic voltammetry proves diffusion controlled, direct one‐electron oxidation of the hydrocarbon. The product of preparative scale electrolysis is analyzed by elemental analysis and various spectroscopic techniques. Bond formation occurs at the vinyl group, resulting in analogues of polystyrene. Polymers are separated on a reversed phase chromatography column, and online coupling to electrospray ionization mass spectrometry as well as a combination of size exclusion chromatography and MALDI‐MS prove the formation of species up to the undecamer. The determination of the molecular product masses allows the assignment of the polymer end groups. A mechanistic hypothesis for the radical cation induced electropolymerization of the monomer is developed from the electro‐chemical and structural results.
Syntheses with Aliphatic Dialdehydes, XLVI. Synthesis and Reactions of 2,2‐Dialkyl‐Substituted Malonaldehydes and Their Semi(Ethylene Acetals)
Authors: Appelhans Dietmar , Reichardt Christian
Published: July 2007

Attempts to synthesize the 2,2‐disubstituted malonaldehydes 3a–h by Swern oxidation of the propane‐1,3‐diols 4a–h led only to polymers of unknown structure, with the exception of 3d,e,f,h, which could be isolated in low yields (ca. 5%) as monomeric compounds. The more stable and hence easier to isolate half‐protected semi(ethylene acetals) of these malonaldehydes, 7a–g, were synthesized from the 2,2‐disubstituted 3‐hydroxypropanals 5a–g via the semiacetals 6a–g. Modified Wittig‐Horner olefination reactions of the malonaldehyde semiacetals 7, followed by hydrolysis, led to derivatives of butane‐1,4‐dial, 9b–e,g, and pent‐3‐ene‐1,5‐dial, 10a–e,g, thus demonstrating the synthetic utility of the new malonaldehyde derivatives 7.
Molecular Bowls and Capsules with an Endohedral Functionality: The Stabilization of Highly Reactive Species in Their Inner Phase
Authors: Goto Kei , Okazaki Renji
Published: July 2007

Endohedral phases of molecular bowls and capsules have great potential for serving as a reaction environment for the internal functionality as well as a complexing site for the guest molecule. The reactivity of a functional group covalently fixed in the interior of such molecules can be regulated in a unique fashion by the surrounding framework. This article gives an account of the design of novel molecular bowls and capsules bearing an endohedral functionality and the stabilization of highly reactive species by covalent fixation in the interior of such molecules. The target species include a sulfenic acid, a selenenic acid, and a monosubstituted simple enol, which have been recognized as important but elusive intermediates in organic and enzymatic reactions.
Polyhalogenated Cyclopentadienes in [4+2] Cycloadditions: Preparative Aspects
Authors: Eibler Ernst , Burgemeister Thomas , Höcht Peter , Prantl Bernhard , Roßmaier Henry , Schuhbauer Hans Markus , Wiest Hubert , Sauer Jürgen
Published: July 2007

[4+2] Cycloadditions of cyclopentadienes1a–1iwith arylsubstituted cyclic and open‐chain dienophiles usually gave singleendo‐cycloadducts in high yield. Assignment of the product structures involved1H‐NMR spectroscopy including (1H,1H) long‐range coupling and (1H,19F)through‐bondandthrough‐spacecoupling.
7‐Nitro‐7‐deaza‐2′‐deoxyadenosine and 8‐Methyl‐7‐deaza‐2′‐deoxyguanosine: Pyrrolo[2,3‐d]pyrimidine Nucleosides with Different Sugar Conformations
Authors: Seela Frank , Rosemeyer Helmut , Zulauf Matthias , Chen Yaoming , Kastner Guido , Reuter Hans
Published: July 2007

The crystal structures of 7‐nitro‐7‐deaza‐2′ ‐deoxyadenosine (3) and 8‐methyl‐7‐deaza‐2′ ‐deoxyguanosine (5) have been determined and were compared with those of the parent 7‐deaza‐2′ ‐deoxyadenosine (2) and other 7‐substituted 7‐deazapurine 2′ ‐deoxynucleosides 4 and 6. The sugar pucker of compound 3 is N (3′T2′) whereas compound 5 shows 2′E conformation (S‐type). Despite the methyl group, compound 5 exhibits anti conformation about the N‐glycosylic bond as in all other cases. The predominant conformations of 3 and 5 in aqueous solution, determined by 1H NMR spectroscopy, is consistent with those in the solid state.
Studies on Metabolites of Mycoparasitic Fungi, 6. 15‐Hydroxyacorenone: New Acorane‐Type Sesquiterpene from the Culture Broth of the Mycoparasitic Fungus Trichoderma harzianum
Authors: Tezuka Yasuhiro , Tasaki Miyuki , Huang Qing , Hatanaka Yasumaru , Kikuchi Tohru
Published: July 2007

A new acorane‐type sesquiterpene, 15‐hydroxyacorenone, has been isolated from the culture broth of Trichoderma harzianum, which in turn was isolated from the fruiting body of a medicinal mushroom, Ganoderma lucidum (Fr.) Karst. (the oriental crude drug “Lin‐Chi”). The structure of 15‐hydroxy‐acorenone was determined by spectroscopic methods to be (1S,4S,5S)‐8‐hydroxymethyl‐1‐isopropyl‐4‐methylspiro[4.5]‐dec‐8‐en‐7‐one (1).
Functionalized Ozonides by Substitution Reactions of Chlorinated Ozonides with Difunctional Alcohols
Authors: Griesbaum Karl , Quinkert Ralf‐Olaf
Published: July 2007

Substitution of 3‐chloro‐3,5‐bis(chloromethyl)‐5‐methyl‐1,2,4‐trioxolane (3) with allyl alcohol gave the corresponding diastereomeric allyloxy‐substituted ozonides 4, which were converted into diozonides 7 by ozone treatment. Substitutions of 3 with ethanediol or with 1,3‐propanediol gave the corresponding hydroxyalkoxy‐substituted ozonides 8, 14, which were oxidized to the corresponding aldehydes 10, 16. Reaction of 3,5‐dichloro‐3,5‐bis(chloromethyl)‐1,2,4‐trioxolane (1a) with ethanediol gave the corresponding bis(hydroxy)‐substituted ozonide 19 as well as a bicyclic ozonide 18 by reaction of 1a with ethanediol in a ratio of 1:1.
MR imaging of testicular torsion: Features of testicular hemorrhagic necrosis and clinical outcomes
Authors: Watanabe Yuji , Nagayama Masako , Okumura Akira , Amoh Yoshiki , Suga Tsuyoshi , Terai Akihito , Dodo Yoshihiro
Published: July 2007

Purpose

To determine whether emergency subtraction dynamic contrast‐enhanced MR imaging (DCE‐MRI) in combination with T2‐ and T2*‐weighted imaging of the testis is useful in the evaluation of patients with testicular torsion.

Materials and Methods

Fourteen patients with surgically proven testicular torsion were examined using preoperative emergency MRI, including T2‐weighted, T2*‐weighted, and DCE‐MRI. The affected testis was examined histologically in eight patients who underwent orchiectomy, and by postoperative follow‐up MRI in six patients who underwent orchiopexy. The diagnostic criteria for testicular torsion and detection of hemorrhagic necrosis in the affected testis in emergency MRI were decreased or no perfusion in DCE‐MRI and a spotty and/or streaky pattern of low or very low signal intensity in T2‐ and T2*‐weighted images. The intraoperative findings and clinical outcomes were also compared.

Results

The histological findings and follow‐up MR images revealed total or partial necrosis of the affected testis in 10 of the 14 patients. In the diagnosis of complete torsion, the sensitivities were 100% for DCE‐MRI and 75% for T2‐ and T2*‐weighted imaging. In the detection of testicular necrosis, T2‐ and T2*‐weighted imaging showed the highest accuracy (100%), followed by 12‐hour time from onset (93%), intraoperative findings (79%), and DCE‐MRI (71%).

Conclusion

Emergency MRI can help diagnose testicular torsion and detect testicular necrosis when DCE‐MRI is used in combination with T2‐ and T2*‐weighted images. J. Magn. Reson. Imaging 2007;26:100–108. © 2007 Wiley‐Liss, Inc.