bluuebunny/crossref_metadata_2025_split huggingface dataset:
Electron Transfer Initiated Free Radical Additions of Perfluoroalkyl Iodides and Diiodides to Alkenes
Authors: Metzger JüRgen O. , Mahler Ralf , Schmidt Andreas 
Published: June 2010

AbstractPerfluoroalkyl iodides were added in very good yields to 1,2‐dialkyl substituted double bonds of e.g. petroselinic acid initiated by lead/copper(II) acetate in methanol and by copper without solvent, respectively. Using the new initiator system lead/copper(II) acetate, we also obtained good yields in the additions of perfluoroalkyl iodides to allyl alcohol and ω‐unsaturated alcohols and of perfluoroalkyl 1,ω‐diiodides to methyl 10‐undecenoate.
[2 + 2] Photocycloaddition of Two Captodative Alkenes to 3‐Acetylthianaphthene
Authors: Döpp Dietrich , Hassan Alaa A. , Henkel Gerald 
Published: June 2010

AbstractPhotoexcited 3‐acetylbenzo[b]thiophene (1c) adds 2‐morpholinopropenenitrile (2a) in a [2 + 2] mode at the C2C3 bond regioselectively but stereounselectively with formation of cyclobuta[b][1]benzothiophenes 3a and 4a. In addition, the isomeric adduct 5 is formed from 2a and excited 2‐acetylbenzo[b]thiophene (1b) accompanying 1c as an impurity. Similarly, 2‐(tert‐butylthio)propenenitrile (2b) undergoes a smooth and highly regioselective but stereounselective [2 + 2] photoaddition to 1c yielding a mixture of two isomeric adducts from which compound 3b may be separated by recrystallization. The configuration of 5 was unambiguously confirmed by an X‐ray crystal structure analysis. The structures of the other cycloadducts were derived by a comparison of their 1H‐NMR spectral data with those of closely related substances from other work.
Facile Synthesis of Polycyclic pyridines, Bipyridines, and Oligopyridines
Authors: Keuper Ralf , Risch Nikolaus 
Published: June 2010

AbstractThe preparation of polycyclic heterocycles with one or more nitrogen atoms and different binding angles by a domino reaction is described. These compounds (4–6, 8a–b) are formed by the reaction of β‐amino ketone hydrochlorides 1 or 2 (Mannich bases) with ketones 3. Especially the synthesis of the terpyridines 8a and 8b in a double domino reaction is very useful (yield 70 and 59%) and opens a route to torands.
Microwave‐Assisted Diels‐Alder Reaction Supported on Graphite
Authors: Garrigues Bernard , Laporte Christian , Laurent Régis , Laporterie André , Dubac Jacques 
Published: June 2010

AbstractThe coupling of graphite (as a support) with microwaves (as an energy source), a new type of “dry reaction”, was studied for some Diels‐Alder reactions involving anthracene and azadienes. Graphite is responsible for a high‐temperature gradient leading to increased reaction rates as compared to conventional procedures using a solvent.
Dimerizations of 2‐Alkylbenzotriazoles and Chemical Evidence of Radical Intermediates from X‐ray Studies
Authors: Katritzky Alan R. , Jesorka Aldo , Wang Jin , Yang Baozhen , Wu Jing , Steel Peter J. 
Published: June 2010

AbstractTreatment of 2‐alkylbenzotriazoles with lithium diisopropylamide (LDA) at −78°C gave, depending on workup conditions, either dimers of the type Bt2CHRCHRBt2 (2) (Bt2 = benzotriazol‐2‐yl), or mixtures of symmetrical Z and E olefins (3) (RCHCHR), in high yields via radical intermediates. The racemic and meso isomers of 2, which differ substantially in properties such as melting points, 1H and 13C NMR, were isolated and characterized (three by X‐ray crystallography). Both the meso and racemic dimers of 2 were reduced by Na to give mixtures of Z and E olefins in high yields with the elimination of the benzotriazole anion. 2‐Alkylbenzotriazoles (1) were also converted by Na into the corresponding alkanes and benzotriazole. The intermediates were trapped by benzophenone to give, depending on the reaction procedure (see Scheme 2), adducts 6 or adducts 6 with dimers 2, benzotriazol‐2‐ylalkene 7 and compound 8 (R  H), compound 9 (R  CH3). Several compounds with dibenzotriazol‐2‐yl groups or benzotriazol‐1‐yl and benzotriazol‐2‐yl groups in the same molecule were synthesized and further investigated via lithiation followed by the addition of benzophenone or benzaldehyde. This further indicated that the radical reaction is faster than the nucleophilic reaction.
A Transannularly Bridged Bis(calix[4]arene) Forming a Multiple Ansa Compound
Authors: Siepen Astrid , Zett Andreas , Vögtle Fritz 
Published: June 2010

AbstractThe reaction of the chloromethylated calix[4]arene 1 fixed in the “cone” conformation with 4,4′‐dihydroxybiphenyl 2 leads to 4, which is the first example of a bis(calix[4]arene) macrocycle threaded by two intramolecular bridges. It thus contains three cavities in one multiple ansa molecule.
Photoresponsive Carboxylic Acids
Authors: Herges Rainer , Reif Wolfgang 
Published: June 2010

AbstractA norbornadiene tetracarboxylic acid was synthesized the pKs of which can be changed by irradiation forming the quadricyclane derivative or by catalytical reisomerization to the norbornadiene. The pKs difference of both isomers in the second and fourth dissociation step is 0.59 and 0.68 units. Photochemical isomerization proceeds without decomposition at high pH (≥ 9.0). Reisomerization of the quadricyclane to the norbornadiene with a RhI complex is also a clean reaction, but rather slow with t1/2 = 5 d at room temperature. We attribute the pH change of an aqueous solution during isomerization to the formation or cleavage of intramolecular hydrogen bonds between the adjacent carboxyl groups and accumulation or dispersion of negative charge in the quadricyclane and norbornadiene, respectively.
A Facile Synthesis of Dinitro[2.2]metacyclophane and Its Partial Reduction
Authors: Tsuge Akihiko , Moriguchi Tetsuji , Mataka Shuntaro , Tashiro Masashi 
Published: June 2010

AbstractBoth aromatic rings in [2.2]metacyclophanes(MCPs) can be easily nitrated in good yields by using the HNO3/dichloromethane system under mild conditions. This facile method is clearly superior to the nitration by strong nitrating agents such as nitronium tetrafluoroborate. Partial reduction of dinitro[2.2]MCP (2a) affords the intriguing aminonitro[2.2]MCP (3) which is one of the ultimate models of intramolecular charge‐transfer interaction. Compound 3 shows a significant bathochromic shift due to through‐space interaction between two aromatic rings.
[4 + 2] Cycloaddition Reactions of a 4a,8a‐Methanophthalazine with Electron‐Rich Alkynes: A New Synthesis of Substituted 1,6‐Methano[10]annulenes
Authors: Laue Jörg , Seitz Gunther 
Published: June 2010

AbstractThe novel propellane3containing an electron‐rich cyclohexadiene and an electron‐deficient diazadiene system in one and the same molecule reacts site selectively with the electron‐rich alkynes4and8as well as with cyclooctyne (10) to yield the interestingly substituted novel 1,6‐methano[10]annulenes7,9, and11. In contrast to this course of reaction, benzyne (12) undergoes a cycloaddition with the cyclohexadiene moiety of3with high site selectivityantito the methano bridge to furnish the pentacyclic pyridazine derivative14. Interestingly benzyne (12) is able to react with the diazadiene system of the phthalazine17to form the triptycene19via the azo compound18.
Unexpected Pyrazole → 1,2,4‐Triazole Ring Transformation
Authors: Moderhack Dietrich 
Published: June 2010

AbstractThe pyrazolyl‐substituted amidrazones 3 were found to undergo slow conversion into the 1,2,4‐triazolyl ketone hydrazones 8 when kept in ethanolic solution at 20°C. The crucial step in this transformation is apparently air oxidation of 3 to the intermediate 4, since employment of an additional oxidant greatly enhanced the rate.
Tuberosides A, B, and C, Novel Triterpenoid Saponins from the Hypoglucaemic Fraction of Ullucus tuberosus
Authors: Espada Alfonso , Jiménez Carlos , Dopeso Jose , Riguera Ricardo 
Published: June 2010

AbstractThree novel triterpenoid saponins, tuberoside A (1), B (2), and C (3), were isolated as sodium and choline salts from the methanolic extract of the tubers of Ullucus tuberosus Caldas (Syn.: U. kunthii H.B.K.), which shows hypoglucaemic activity. Their structures were established on the basis of 2D‐NMR and FAB‐MS experiments and were confirmed by chemical methods. This is the first chemical study of a plant of the genus Ullucus.
Reactions with Twofold Bridged Sulfone‐Substituted Dewar Benzenes – Preparation of New Dewar Benzene Derivatives
Authors: Ohlbach Frank , Gleiter Rolf , Oeser Thomas , Irngartinger Hermann 
Published: June 2010

AbstractThe twofold bridged sulfone‐substituted Dewar benzenes 15,16‐bis(tert‐butylsulfonyl)tetracyclo[7.5.2.01,9.02,8]hexadeca‐2(8),15‐diene (7a), 17,18‐bis(tert‐butylsulfonyl)tetracyclo[8.6.2.01,10.02,9]octadeca‐2(9),17‐diene (7b), 2,3‐bis(tert‐butylsulfonyl)‐1,4,5,6‐tetramethylbicyclo[2.2.0]hexa‐2,5‐diene (11), and 15‐(phenylsulfonyl)‐16‐(trimethylsilyl)tetracyclo[7.5.2.01,9.02,8]hexadeca‐2(8),15‐diene (13a) were treated with SmI2, methyllithium, phenyllithium, and methyl, phenyl, and benzyl Grignard reagents, respectively. In the case of the reduction with SmI2 one tert‐butylsulfonyl substituent (7a, 7b, 11) and the phenylsulfonyl group in 13a could be removed. Compound 7a reacts with methyllithium and phenyllithium with replacement of one RSO2 substituent by the alkyl or aryl group, respectively. With methyl and benzylmagnesium bromide both RSO2 groups in 7a could be replaced. The reaction of 7a with phenylmagnesium bromide leads to the mono‐ and disubstituted products and in addition to dimers of substituted phenyl Dewar benzenes. For the reaction with organolithium and Grignard compounds there are indications of a SET mechanism. The X‐ray structures of 15,16‐dimethyltetracyclo[7.5.2.01,9.02,8]hexadeca‐2(8),15‐diene (32a) and the corresponding dibenzyl derivative 834a) were investigated by using single crystals.
Synthesis of rac‐Presilphiperfolan‐9‐ol
Authors: Weyerstahl Peter , Marschall Helga , Schulze Matthias , Schwope Ina 
Published: June 2010

Abstractrac‐Presilphiperfolan‐9‐ol (2) and three of its epimers (24, 29, 30) were synthesized by starting from the known 8‐hydroxy‐3,3,5‐trimethylbicyclo[3.3.0]octan‐2‐one (10). The spectroscopic data of rac‐2 are identical with those of the natural (‐)‐presilphiperfolan‐9‐ol, previously isolated from Artemisia laciniata. rac‐2 has a strong woody, amber odor whereas the 9‐epimer 24 smells strongly patchouli‐like.
Structure‐Odor Correlation, XXIV. Synthesis and Olfactory Properties of Damascone and Damascenone Analogs
Authors: Weyerstahl Peter , Licha Kai 
Published: June 2010

AbstractThe aldehydes rac‐1, rac‐2, and 3 were conveniently prepared by starting from isophorone (4). Reaction of 1–3 with (E,Z)‐1‐bromo‐1‐propene (14) afforded the rac‐allylic alcohols (E,Z)‐15, ‐18, and ‐20. The alcohols were oxidized to the damascone/damascenone analogs 1‐(3,5,5‐trimethyl‐2‐cyclohexen‐1‐yl)‐ (rac‐16), 1‐(3,5,5‐trimethyl‐1‐cyclohexen‐1‐yl)‐ (rac‐19), and 1‐(3,5,5‐trimethyl‐1,3‐cyclohexadien‐1‐yl)‐2‐buten‐1‐one (21), and the (E/Z) isomers were separated by FC. Their olfactory evaluation shows that the highly estimated odor of damascone (A, B) and damascenone (C) is more or less lost. This result can be explained by force‐field calculation of the lowest energy conformation of 16, 19, and 21 in comparison with those of A–C.
Thermal Isomerisations, XXIV. Gas Phase Kinetics of the Pyrolysis of Some 3,3‐Dimethyl‐1‐alkyl‐cyclopropenes: Some Surprising Substituent Activation Effects and the Intramolecular Trapping of Vinylidene Intermediates
Authors: Hopf Henning , Plagens Andreas , Walsh Robin 
Published: June 2010

AbstractThe gas phase pyrolyses of four 3,3‐dimethyl‐1‐alkylcyclopropenes were studied for which the 1‐alkyl substituents are ethyl‐ (6), isopropyl‐ (7), 1′‐butyl‐ (8) and 1′‐isoamyl‐ (9). Rate data over a 50°C temperature range were obtained and Arrhenius parameters are reported both for overall reactions and individual pathways for all compounds. Tests confirm all reactions to be unimolecular and homogeneous. For 8 and 9, noteworthy products are cyclopentenes, whose presence demonstrates the involvement of vinylidene intermediates. The substantial product yields of 2,4‐alkadienes together with dramatic rate enhancement effects of these 1‐alkyl substituents (relative to 1‐methyl) are explained by the involvement of vinylcarbene intermediates in this pathway. Minor, transient products from 6, 8 and 9 are probably isomeric cyclopropenes. This suggests further pathways for vinylidene intermediates, whose reactivity pattern is briefly reviewed.
Biologically Active Glycosides from Asteroidea, 35. Isolation and Structure of Four New Steroid Glycoside Di‐O‐sulfates from the Starfish Asteropecten latespinosus
Authors: Higuchi Ryuichi , Fujita Masanori , Matsumoto Shuji , Yamada Koji , Miyamoto Tomofumi , Sasaki Takuma 
Published: June 2010

AbstractFour new steroid di‐O‐sulfates, latespinoside A (1), B (2), C (3), and D (4), were isolated from the crude glycoside fraction of the chloroform/methanol extract of the starfish Asteropecten latespinosus as minor components. Their structures were determined on the basis of spectral data as disodium salts of (20S)‐20‐hydroxy‐6α‐(4‐O‐sulfo‐β‐D‐quinovopyranosyloxy)‐3β‐sulfooxy‐5α‐cholesta‐9(11),24‐diene (1), (20S)‐20‐hydroxy‐6α‐(4‐O‐sulfo‐β‐D‐quinovopyranosyloxy)‐3β‐sulfooxy‐5α‐cholest‐9(11)‐ene (2), 6α‐(4‐O‐sulfo‐β‐D‐quinovopyranosyloxy)‐3β‐sulfooxy‐5α‐cholesta‐9(11),17(20)Z,24‐trien‐23‐one (3), and 6α‐(4‐O‐sulfo‐β‐D‐quinovopyranosyloxy)‐3β‐sulfooxy‐5α‐androst‐9(11)‐en‐17‐one (4). Compound 4 is, to the authors' knowledge, the first androstane derivative isolated from starfish. In addition, compounds 3 and 4 show weakly cytotoxic activity against murine lymphoma L1210 cells in vitro.
Cycloadditionen von 6H‐1,3,4‐Oxadiazin‐6‐onen (4,5‐Diaza‐α‐pyronen), 15.Reaktionen von 6H‐1,3,4‐Oxadiazin‐6‐onen mit Norbornadien. Ein neuer Weg zu 3,6‐disubstituierten α‐Pyronen
Authors: Christl Manfred , Bodenschatz Gabriele , Feineis Erich , Hegmann Joachim , Hüttner Gerhard , Mertelmeyer Stefan , Schätzlein Klaus 
Published: June 2010

AbstractCycloadditions of 6H‐1,2,4‐Oxadiazin‐6‐ones (4,5‐Diaza‐α‐pyrones), 15.Part 14: Ref.[1].

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Reactions of 6H‐1,3,4‐Oxadiazin‐6‐ones with Norbornadiene. A New Route to 3,6‐Disubstituted α‐Pyrones
Upon reaction with norbornadiene, ten disubstituted 1,3,4‐oxadiazin‐6‐ones 1 were converted into 3,6‐disubstituted α‐pyrones 6. For this purpose, solutions of the substrates were treated with boron trifluoride‐ether or trifluoroacetic acid. The smooth formation of 6 was also observed when a γ‐oxo ketene, initially generated by heating a solution of the substrates in the absence of boron trifluoride–ether, was allowed to react with the Lewis acid. Without use of an acid, only 6f could be obtained free from further compounds, whereas in the other cases enol lactones and 1:2 products of the types 8 and 7 were formed additionally. Oxadiazinone 1j gave enol lactone 10 in the noncatalysed reaction.
Triazolo[4,5‐b]‐ and Imidazo[4,5‐b]pyridines as Substrates of NAD Glycohydrolase: Evidence for Two Competitive Transglycosylatin Reaction Sites
Authors: Tono‐Oka Shuichi , Azuma Ichiro 
Published: June 2010

AbstractThe NAD+ glycohydrolase‐catalysed transglycosidation reaction of pyrido‐annulated triazole 1 and imidazole 2 was investigated. In both cases two regioisomers, N1‐ribosylated (3 and 5) and N3‐ribosylated products (4 and 6), were efficiently obtained in roughly equal ratio. The regioisomers were distinguished from each other on the basis of 15N‐NMR data. The present study furnished evidence of two competitive sites of transglycosidation in the triazole 1 and the imidazole 2. The occurrence of competition is probably attributable to a tautomeric equilibrium between 1a and 1b (2a and 2b).
New Types of Nonionic Surfactants with Sugar Head Groups
Authors: Schmidt Richard R. , Jankowski Karin 
Published: June 2010

AbstractThe head group/lipophilic tail ratio is used to categorize amphiphilic compounds into different types. Some representatives of the 2/1 type with two sugar head groups and one lipophilic chain, namely compounds 6a–d, were synthesized from readily available precursors. Similarly, from 2,3‐di‐O‐alkyl and 1,3‐di‐O‐alkyl derivatives of D‐threitol 2/2‐type amphiphiles 13a–d, 15a–d and 20a–d, respectively, were obtained. Due to the different spatial demand of the sugar moieties relative to the lipophilic part, surface tension (σ) and critical micelle concentration (cmc) are clearly distinguished in these different structural types of nonionic surfactants.
3H‐Azepines by Intramolecular Condensation Reaction of 1,6‐Diamino‐1,3,5‐hexatrienes
Authors: Kowalski Dorothee , Erker Gerhard , Kotila Sirpa 
Published: June 2010

Abstract2,7‐Disubstituted 3H‐azepines (2a–d) are obtained by acidcatalyzed thermolytic deamination of 1,6‐disubstituted 1,6‐diamino‐1,3,5‐hexatrienes 1a–d in moderate yields. The reaction probably involves reversible conjugated enamine ⇌ imine tautomerization indicated by the formation of the respective five‐membered ring competition products 3. Compounds 2a and 3b were characterized by X‐ray diffraction.
The Use of Vicinal Twofold Heck Reaction Products in Diastereoselective Sequential Michael Additions — A Convenient Access to Enantiomerically Pure Six‐Ring Anellated Cispentacin Derivatives
Authors: Voigt Katharina , Lansky Annegret , de Meijere Armin , Noltemeyer Mathias 
Published: June 2010

AbstractThe palladium‐catalyzed coupling reactions of various acrylic acid derivatives 2a–e (e.g. methyl, tert‐butyl, benzyl, menthyl esters) with 1,2‐dibromobenzene (1), 1,2,3‐tribromobenzene (4) and 1,2‐dibromocyclohexene (6) yielded the correspondingly substituted ortho‐diethenylarenes 3a–e, 1,2,3‐triethenylarenes 5a,b and (E,E)‐1,3,5‐hexatriene derivatives 7a,b. Some of these vicinal diacrylates (3a–d, 5b, 7a,b) were converted to 1,2,3‐trisubstituted indane‐ and tetrahydroindane derivatives 10a–d, 15a,b, 18, 20, 23, and 12a,b, 16b by domino conjugate addition of nitrogen, carbon, and sulfur nucleophiles. With benzyl(trimethylsilyl)amine (9) as an ammonia equivalent, the relative configuration of all three newly formed stereogenic centers was controlled (d.e. >90%). Therefore, with chiral non‐racemic ammonia equivalents like benzyl[(S)‐phenylethyl]amine (14) and TMS‐(R)‐AMP (17), protected diastereomerically pure β‐amino esters were obtained, which could easily be deprotected by standard methods to yield the enantiomerically pure β‐amino acids 27 and 28.
Porphyrin Blocking Groups in Amide‐Based Rotaxanes
Authors: Vögtle Fritz , Ahuis Friedrich , Baumann Sven , Sessler Jonathan L. 
Published: June 2010

AbstractThe synthesis of amide‐based symmetrical rotaxanes2a,bbearing porphyrin blocking groups is firstly described. These compounds can be obtained by a one‐step one‐pot reaction only if the macromonocyclic host template complementary to the threading guest is found. The symmetry of the axle is removed by introducing an unsymmetrical central part, leading to the formation of rotaxane2c. Different blocking groups were used to obtain the non‐symmetrical rotaxane3a. The bis‐Zn2+complex10aof the rotaxane2awas isolated. A nonionic supramolecular complex7was assumed as threaded intermediate, which was blocked by reaction with the stopper components. The amide‐type rotaxane system thus proved to be variable with respect to all its parts including stopper components of different reactivity, bulkiness and supramolecular functionality.
Transesterification of Phosphodiester by a Zinc‐Containing Cyclen Derivative: Identification of the Active Species
Authors: Kalesse Markus , Loos Andrea 
Published: June 2010

AbstractThe active site analogue 2 of alkaline phosphatase was synthesized and its hydrolytic activity was tested. Efficient hydrolysis was observed at pH > 8 at various concentrations of the hydrolytic species. The cyclic phosphate 3 derived from transesterification could be identified by 31P‐NMR spectroscopy. A comparison of the hydrolysis results with the species distribution curve revealed the ZnLOH species as the active complex. The complex stability constant (log KZnL) of ligand 7 was determined to be 13.7 (± 0.5). K′ for the hydrolysis of the p‐nitrophenyl phosphate ester of propylene glycol (1) with 2 (0.02 M, pH = 8.35) is 1.5 × 10−3 s−1 at 50°C.
Identification and Synthesis of Elymniafuran, a New Monoterpene from the Butterfly Elymnias thryallis
Authors: Schulz Stefan , Steffensky Mirjam , Roisin Yves 
Published: June 2010

AbstractThe main constituent of the scent gland secretion of the tropical butterfly Elymnias thryallis (Lepidoptera: Satyridae) could be identified as (S)‐2‐methyl‐1‐(4‐methyl‐2‐furyl)‐3‐buten‐2‐ol (elymniafuran, 3). It is accompanied by small amounts of (E)‐ and (Z)‐4‐methyl‐(2‐methyl‐1,3‐butadienyl)‐furan (4) as well as the spiro acetal 3,9‐dimethyl‐1,6‐dioxaspiro[4.5]dec‐3‐ene (10). The structural assignment of these new natural products as well as the synthesis and enantiomeric separation by chiral gas chromatography are described.
Determination of the Rotational Energy Barrier of Planar‐Chiral Cyclophanes Using Dynamic Enantioselective Gas Chromatography and Computer Simulation
Authors: Hochmuth Detlev H. , König Wilfried A. 
Published: June 2010

AbstractWe synthesized numerous new monosubstituted dioxa[11]‐paracyclophanes, which are planar‐chiral atropisomers due to the hindered rotation of the bridge about the aromatic plane, and we were able to resolve the enantiomers of these compounds by enantioselective gas chromatography with selectively modified cyclodextrins as chiral stationary phases in polysiloxane solution. As a consequence of the competition between enantiomeric resolution and enantiomerization (interconversion) during the gas chromatographic process, coalescence phenomena or formation of plateaus between the peaks of both enantiomers are observable. The combination of these dynamic gas chromatographic investigations with computer simulation of elution profiles allows the facile and precise determination of the energy barrier of the enantiomerization reaction and the elucidation of the influence of substituents on the energy barrier.
An Unusual C‐1C‐2 Ring‐Splitting of Pyranosides by a Retro‐Aldol Reaction — a Route to New Chiral Building Blocks
Authors: Peseke Klaus , Aldinger Stephan , Reinke Helmut 
Published: June 2010

AbstractThe treatment of the α‐oxoketene dithioacetal sugar derivatives 2 and 7 with concentrated hydrochloric acid in THF leads to the open‐chain uloses 3 and 8. The reaction mechanism can be rationalized as a retro‐aldol reaction. This rationalization was supported by reacting 2 and 7 with DCl/D2O. Compound 3 was converted into the chiral pyrazoles 12 and 13. The branched‐chain ulose 2 forms the thiopyranosidulose 15 when treated with diluted aqueous sulfuric acid in THF. The mechanism of this reaction was investigated by 13C‐labelling of the starting compound 2.
Functionalized Derivatives of Benzocrown Ethers, I. Ionophores Containing Amino and Pyridinium Groups Derived From Benzo‐15‐crown‐5, Benzo‐18‐crown‐6, and Dibenzo‐18‐crown‐6
Authors: Barboiu Mihai , Popescu Georgeta , Barboiu Camelia , Supuran Claudiu T. , Luca Constantin 
Published: June 2010

AbstractAcylation reactions of benzocrown ethers with N‐phthalimido‐protected derivatives of β‐alanine and 11‐aminoundecanoic acid, respectively, were investigated in acid catalysis by using the Eaton reagent. Deprotection of the obtained compounds by hydrazinolysis afforded derivatives with free amino groups the reaction of which with one or two equivalents of 2,4,6‐trisubstituted pyrylium salts furnished pyridinium derivatives. All these new benzocrown ether derivatives were characterized by elemental analysis and IR and NMR spectroscopy.
Synthesis of the First Chiral Bisindolyl Monomethinium Cyanine Dyes
Authors: Eggers Lutz , Buß Volker 
Published: June 2010

AbstractThe synthesis of the chiral monomethine cyanine dyes 8 and 9 starting with the achiral indole 1 is described. Key intermediates are the new chiral Fischer bases R‐ and S‐4, which were separated after diastereomeric salt formation. The conformation of the dyes 8 and 9 is twisted di‐Z, according to NOE and dynamic NMR spectroscopy. The free energy difference between oppositely twisted conformations is ca. 2.5 kJ mol−1.