bluuebunny/crossref_metadata_2025_split huggingface dataset:
Reactions of Cyclic Diynes with Acceptor‐Substituted Alkynes: Syntheses of Doubly Bridged Dewar Benzenes
Authors: Gleiter Rolf , Ohlbach Frank , Oeser Thomas , Irngartinger Hermann 
Published: June 2010

AbstractThe reaction of the AlCl3 complex of cyclic diynes (mainly a 14‐membered ring) with dimethyl acetylenedicarboxylate (DMAD) or bis(tert‐butylsulfonyl)acetylene (BTSA) and related compounds was investigated. The reaction of the AlCl3 complex of cyclotetradeca‐1,8‐diyne (1, n = 5) with DMAD affords in 60% yield two isomers in a ratio of 7:3. The isomers were identified as the 1,4‐ and 2,3‐bridged Dewar benzene derivative A and the 1,2‐ and 3,4‐bridged Dewar benzene derivative B. Acetylenes with sterically more demanding groups such as BTSA or bis(diphenylphosphanyl)acetylene P,P′‐dioxide (BDPA) yield only the isomer A. The X‐ray structures of the cycloadduct between 1 (n = 5 and 6) and BTSA, as well as of 2,3‐bis(tert‐butylsulfonyl)‐1,4,5,6‐tetramethylbicyclo[2.2.0]hexa‐2,5‐diene (31) are described. The mechanism of the cycloadditions is discussed.
A Convenient Synthesis of S‐[(2R)‐2‐Acetamido‐3‐(hexadecyloxy)propyl] 2‐(Trimethylammonio)ethyl Thiophosphate, a New Amido‐Thiophosphate Analog of PAF
Authors: Młotkowska Barbara , Pościk Adam 
Published: June 2010

AbstractThe naturally configurated S‐[(2R)‐2‐acetamido‐3‐(hexadecyloxy)propyl] 2‐(trimethylammonio)ethyl thiophosphate (5), a new amido‐thiophosphate analog of the Platelet Activating Factor (PAF), was obtained in a seven‐step reaction sequence by starting from N‐acetyl‐l‐cysteine (6).
Phosphanalkylene, 55 Reaktionen von Alkylidentriphenylphosphoranen mit nitrierenden Reagentien
Authors: Bestmann Hans Jürgen , Kamberger Werner , Röder Thomas , Zimmermann Reiner 
Published: June 2010

AbstractPhosphane Alkylenes, 55.— Reactions of Alkylidenetriphenylphosphoranes with Nitrating ReagentsThe reaction of phosphonium ylides 1 with N2O4 (2) is strongly influenced by the natur of the substituents of the starting ylide. Formation of α‐nitro‐α‐nitrosoalkanoates 8, nitrolic acid 11, and nitriles 13 was realized. Nitration at the phenyl group of benzylidenephosphoranes 24 or at the γ‐position of allylidenephosphoranes 30 accompanied by transylidation and oxidation processes leads to the formation of nitro‐substituted ylides 26 and 32, respectively. Strongly basic ylides and ethyl nitrate (34) undergo complex reactions as is shown in the formation of the aziridinyl‐substituted ylide 40 from ethylidenetriphenylphosphorane (9) and 34. Allylidenetriphenylphosphoranes 41 are nitrated by ethyl nitrate (34) at the γ‐position affording (γ‐nitroallylidene)triphenylphosphoranes 43, from which nitro dienes 45 are available. In the reaction of 1‐(dimethylamino)‐2‐nitroethylene (46) with phosphonium ylides nitro‐vinylation of the starting ylide takes place.
Synthesis of Mono‐ and Sesquiterpenoids, XXV. Synthesis of (6R*,7R*)‐7‐Hydroxy‐6,11‐cyclofarnes‐3(15)‐en‐2‐one, the Racemate of the Antibacterial Sesquiterpene from Premna oligotricha, and Its (6R*,7S*) Isomer
Authors: Yajima Arata , Takikawa Hirosato , Mori Kenji 
Published: June 2010

AbstractThe structure of the antibacterial sesquiterpene from Premna oligotricha was shown to be not 1 but 2 (relative stereochemistry) by the unambiguous synthesis of both (±)‐1 and (±)‐2.
Geometries of Three‐Membered Rings in Triangulanes and Spirocyclopropanated Bicyclopropylidenes: Experimental Studies and a General Bond Increment Scheme
Authors: Boese Roland , Haumann Thomas , Jemmis Eluvathingal D. , Kiran B. , Kozhushkov Sergei , de Meijere Armin 
Published: June 2010

AbstractCrystal structural studies of several linear and branched triangulanes, together with spiro‐cyclopropanated bicyclopropylidenes, by X‐ray diffraction reveal significant differences between proximal and distal bond lengths in the three‐membered rings. Combined with previously published structural data, these results allowed us to elaborate a general additivity scheme describing the geometry of such hydrocarbons. The π donor spirocyclopropane and a double bond shorten the proximal bonds by 0.0234 and 0.0327 Å and lengthen the distal bonds by 0.0227 and 0.0327 Å with respect to the unperturbed value of 1.5008 Å. The results of these calculations were compared with those obtained by semiempirical and ab initio methods and explained qualitatively by using the Fragment Molecular Orbital (FMO) approach.
Enol Cation Radicals in Solution, 9. Synthesis and One‐Electron Oxidation Chemistry of Novel, Stable Conjugated Dienols and Yne‐Enols
Authors: Schmittel Michael , Langels Anja 
Published: June 2010

AbstractFor the first time stable enols containing the 1,3‐dien‐2‐ol and the yne‐enol functionalities were synthesized, characterized and investigated by cyclic voltammetry. According to the spectral data and AM1 calculations full conjugation between the enol moiety and the vinyl or alkynyl substituents was attained. One‐electron oxidation of enols E1–5 with tris(1,10‐phenanthroline)iron(III) hexafluorophosphate provided in most cases the novel benzofurans B that were isolated and characterized. The mechanism of the benzofuran formation is discussed.
The First Tetrathio‐Substituted Cyclobutane‐1,2,3,4‐tetracarbonitrile — A New Highly Substituted Cyclobutane
Authors: Spannenberg Anke , Holdt Hans‐Jürgen , Teller Joachim , Praefcke Klaus , Kopf Jürgen 
Published: June 2010

AbstractThe first tetrathio‐substituted cyclobutane‐1,2,3,4‐tetracarbonitrile 9 was obtained by an intramolecular photoinduced [2 + 2] cycloaddition reaction of the 14‐membered macrocyclic tetrathioether 7 containing two 1,2‐dicyano‐1,2‐dithioethene units in dichloromethane in 73% yield.
Stereoelectronic Effects and Chiral Recognition, II. Kinetic and Thermodynamic Control in the Formation of Chiral Thioacetals and Chiral Thioethers
Authors: Noe Christian R. , Knollmiiller Max , Ziebarth‐Schroth Irene , Letschnig Marion 
Published: June 2010

AbstractThe ratio of diastereomers obtained from chiral thiols 2 was shown to be time‐dependent both in thioacetal formation with lactol 1 (diastereomers 3/4) and in 1,4‐addition to nitrostyrene 5 (diastereomers 6/7, 8/9). An interpretation based on stereoelectronic effects is presented to explain the similarity of the reaction pathways in both reactions.
Diastereo‐ and Enantioselective Diels‐Alder Reactions of 2‐Amino‐1,3‐dienes
Authors: Enders Dieter , Meyer Oliver 
Published: June 2010

AbstractThe employment of 2‐amino substituted 1,3‐dienes in cycloaddition reactions has recently extended the scope of Diels‐Alder methodologies. In this review, the preparation of a variety of 2‐amino‐1,3‐dienes is presented, and the use of these cross conjugated enamines in normal as well as hetero Diels‐Alder reactions is depicted. Diastereo‐ and enantioselective variations show new aspects for the preparation of cyclic carbonyl compounds in a highly stereoselective fashion. Further cyclisation reactions e.g. cyclopropanation reactions are also considered in this account.
Photochemical Fragmentation of Unsubstituted Tetrazole, 1,2,3‐Triazole, and 1,2,4‐Triazole: First Matrix‐Spectroscopic Identification of Nitrilimine HCNNH
Authors: Maier Günther , Eckwert Jürgen , Bothur Axel , Reisenauer Hans Peter , Schmidt Christiane 
Published: June 2010

AbstractEquilibria between the tautomers of heterocyclic azoles like 1, 2, and 4 have been studied many times. We here show that the application of density functional methods in combination with matrix IR spectroscopy is a useful tool for determining which protomer is preferred in rare gas matrices and thus also can be assumed to dominate in the gas phase. Photolysis of tetrazole (4) in cryogenic matrices allows the IR‐spectroscopic identification of a new CH2N2 isomer, the long soughtafter nitrilimine HCNNH (6). Flash pyrolysis of 4 also yielded nitrilimine. Upon irradiation this species is converted to a second, previously unknown “isomer”, an HCN/NH complex 13. Nitrilimine (6) can also be generated by photolyzing 1,2,3‐ (1) and 1,2,4‐triazole (2) in Ar matrices. The complex photochemistry of all three heterocyclic precursor compounds was unveiled. Our findings were supported by isotopic substitution experiments and by high‐level ab initio calculations. Moreover, the IR bands of iminocyanide HNCN were tentatively assigned. This radical has up to now not been observed in a matrix.
Synthetic Microbiol Chemistry, XXIX!. Synthesis of Both the Enantiomers of Incrustoporin, an Antibiotic from Incrustoporia carneola
Authors: Yajima Arata , Mori Kenji 
Published: June 2010

AbstractBoth the enantiomers of incrustoporin (2‐p‐tolyl‐2‐hexen‐4‐olide, 1) were synthesized by starting from methyl p‐tolylacetate (2) and (S)‐1,2‐epoxybutane (3). The naturally occurring compound 1 was shown to possess the R configuration.
The First Asymmetric Carroll Rearrangement Diastereo‐ and Enantioselective Synthesis of Polyfunctional Ketones with Vicinal Quaternary and Tertiary Stereogenic Centers
Authors: Enders Dieter , Knopp Monika , Runsink Jan , Raabe Gerhard 
Published: June 2010

AbstractThe first asymmetric Carroll rearrangement opens up an efficient access to highly functionalised ketones 4 and 7 with vicinal quaternary and tertiary stereogenic centres of excellent diastereo‐ and enantiomeric purity (de =89–96%, ee =82 to >98%) by using the SAMP/RAMP hydrazone methodology. Starting from hydrazones (S)‐2, we describe a dianionic and a Lewis acid‐mediated variant of the [3.3]‐sigmatropic Carroll rearrangement. The relative and absolute configuration of the new stereogenic centres created by C–C bond formation were assigned by X‐ray crystallographic analysis of the hydrazones 3h and 3j.
Selective Acylations of Multifunctional Nucleophiles, Including Carbohydrates and Nucleosides, with Intermediates Generated by Wolff Rearrangement of Amino Acid Derived Diazo Ketones: Preparation of β‐Amino Acid Derivatives
Authors: Guibourdenche Christel , Podlech Joachim , Seebach Dieter 
Published: June 2010

AbstractThe diazo ketones derived from Z‐ and Boc‐protected alanine, valine, and alanyl‐alanine (1–5) were decomposed by catalytic amounts of silver benzoate/Et3N in the presence of polyfunctional nucleophiles such as 3‐methyl‐1,3‐butanediol, 2‐aminoethanol, carbohydrates (xylofuranose and sucrose) and nucleosides (thymidine, adenosine derivatives). In many cases, products of β‐amino acylations are formed (6–14, 15b, 17–19, 21, 23, 24) with surprising functional group selectivities. The scope and limitations of the method are described.
Restricted Flexibility of the Glycosidic Linkage in α(1→3)‐L‐Digitoxosides as Determined by NMR Spectroscopy and MMC Calculations
Authors: Köpper Sabine , Meyer Bernd 
Published: June 2010

AbstractThe preferred conformations of nine protected α(1→3)‐linked digitoxoside trisaccharides 1–9, α‐L‐Dig‐(1–3)‐α‐L‐Dig‐(1–3)‐α‐L‐Dig (C–B–A), constituents of tetronolide antibiotics, were determined by a combination of 300‐MHz NMR spectroscopy and potential energy calculations using the GEGOP programme. Chemical shift differences and nuclear Overhauser enhancements indicated some unusual short distances between not directly bound digitoxose residues A and C. Thus, the glycosidic linkages of the nine α(1→3)‐linked digitoxosides have a fairly high rigidity as indicated by the relatively large absolute NOE (≈︁3%) from 1C‐H to 5A‐H. MMC simulations of the conformational flexibility resulted in preferred conformations of the glycosidic linkages of ΦC,B/ΨC,B ≈︁ 70°/40° and ΦB,A/ΨB,A ≈︁ 65°/50° with ranges of 40°/50° and 50°/60°. By energy minimisations a second minimum was identified for the B–A glycosidic linkage at ΦB,A/ΨB,A ≈︁ 0°/40° with an energy higher than 2.0 kcal/mol to the main minimum. The MMC‐derived ensemble‐averaged NOEs that were obtained by sampling the main minimum agree well with the experimental values, whereas NOEs derived from MMC runs that stayed at the local minima are not in accord with experimental values. The MMC simulations failed to give transitions between the two minima presumably because of a high energy barrier between the minima. All nine trisaccharides seem to adopt a well‐defined conformation characterised by a narrow distribution in the conformational space that is located in the region of the global minimum.
Intermolecular Hetero Diels‐Alder Reactions of Enamino Ketones with Highly Substituted Vinyl Ethers Effect of High Pressure on the Kinetics and Diastereoselectivity
Authors: Buback Michael , Kuchta Gabriele , Niklaus Anja , Henrich Marielouise , Rothert Iris , Tietze Lutz F. 
Published: June 2010

AbstractThe hetero Diels‐Alder reactions of enamino ketones 1 and 2 with the vinyl ethers 3–5a are studied in dichloromethane solution under high pressures up to 5 kbar. The kinetics is measured by on‐line FT‐IR spectroscopy to 3 kbar. The cycloaddition reactions of enamino ketones 1 and 2 with vinyl ethers 3 and 4 yield the diastereomeric dihydropyrans 7a–d and 8a–d, respectively, whereas in the cycloaddition of enamino ketone 1 to vinyl ether 5a the constitutional isomers 9 and 11 are formed. The unexpected reaction of 1 with 5a to give the spiro compound 9 is explained by isomerisation of 5a to 5b under the reaction conditions. The kinetics of the reactions is discussed in terms of both overall and individual rate coefficients, activation energies, and activation volumes
Structures and Properties of Tris(donor)‐Tris(acceptor)‐Substituted Benzenes, 8!!. On the Balance of Steric, Electronic and Hydrogen Bond Effects in 1,3,5‐Tris(amino)‐2,4,6‐Tris(acceptor)‐Substituted Benzenes
Authors: Jens Wolff J. , Gredel Frank , Hillenbrand Daniela , Irngartinger Hermann 
Published: June 2010

AbstractThe conformational properties of triamino‐substituted 1,3,5‐trinitrobenzenes were studied by X‐ray crystallography, dynamic NMR spectroscopy, and semiempirical calculations. As amino substituents all possible combinations of a dialkyl‐, a monoalkylamino, and an amino group were used. All derivatives have radialene‐like structures with the central six‐membered ring distorted from planarity. The geometric form of the latter was linked with the electronic organization of the π system. Despite the presence of up to six intramolecular hydrogen bonds, semi‐empirical calculations reproduce experimental geometries quite well.
Base‐Catalyzed Dehalogenation of 2,6‐Di‐tert‐butyl‐4‐iodophenol Formation and Structure of a New Oxocyclohexadienylidene Bisphenol
Authors: Reischl Gerald , Rieker Anton , Maichle‐Mössmer Cäcilia , Abram Sonja 
Published: June 2010

Abstract2,6‐Di‐tert‐butyl‐4‐iodophenol (1) does not react to the keto carbene 4 under strongly basic conditions and exclusion of oxygen, in contrast to a report in the literature. In the presence of oxygen, however, oxidation takes place. Reaction times and product pattern strongly depend on the concentration of O2. Besides biphenyl 2, diphenoquinone 3, and quinone 5, a new (oxocyclohexadienylidene)bisphenol 6 was isolated, and its molecular structure was determined by X‐ray crystallography. A radical mechanism is suggested for the formation of the above products from 1. The bisphenol 6 was also synthesized by thermolysis of the quinone diazide 11 in the presence of 3.
Chemistry with Roataxanes: Intra‐ and Intermolecularly Covalently Linked Rotaxanes
Authors: Jäger Ralf , Händel Mirko , Harren Jörg , Vögtle Fritz , Rissanen Kari 
Published: June 2010

AbstractThe direct introduction of sulfonamide units (cf.9) into carboxamide‐based rotaxanes allows us to intramolecularly bridge the “wheel” and the “axle” of such species for the first time as is shown by the bridged bissulfonamide rotaxane11. Due to its stronger acidity the SO2‐NHproton can be selectively abstracted by mild bases even in the presence of CO.NHand then be substituted by treatment with suitable iodo compounds. This leads intramolecularly to11(71% yield) and intermolecularly to bis[2]rotaxane16(76% yield). The iodo‐substituted rotaxane15isolated as a remarkably stable byproduct offers a new synthetic potential demonstrated by the preparation of16.
(–)‐Methyl Cucurbate and (–)‐Methyl Jasmonate by Kinetic Resolution
Authors: Borm Claudia , Winterfeldt Ekkehard 
Published: June 2010

AbstractThe kinetic resolution of a malonate‐substituted cyclopentenone gave rise to the formation of an enantiopure Diels‐Alder adduct which was converted into methyl dehydrocucurbate 2 by diastereoselective alkylation with (Z)‐1‐bromo‐2‐pentene and subsequent borohydride reduction. Selective hydrogenation of 2 with a palladium/calcium carbonate catalyst proved to be a reliable route to (–)‐methyl cucurbate (1) the oxidation of which with pyridinium chlorochromate and subsequent treatment with acid afforded (–)‐methyl jasmonate (9).
ortho‐Azobenzenophanes: Photochemical and Thermal Reactions of [2,2][2,2′]Azobenzenophane
Authors: Tauer Erich , Machinek Reinhard 
Published: June 2010

AbstractThe cyclic azo compounds 6 and 7 were synthesized. The chemical properties of 6 were investigated. Irradiation of the trans,trans form 6t,t leads to isomerization to the trans,cis form 6t,c and to the cis,cis form 6c,c. Compounds 6t,c and 6c,c can be isolated. However, thermally, 6t,c and 6c,c react slowly back to 6t,t. All attempts to convert 6 by light into the tetrazetidine 10 have been unsuccessful until now. In boiling toluene 6 undergoes an interesting rearrangement, namely a ring contraction, during which an azo group is cleaved with formation of an indole ring and a primary amino group.
Synthesis of Novel C‐Methylflavones
Authors: Hauteville Marcelle , Gaillard Pascale , Duclos Marie‐Christine , Kaouadji Mourad 
Published: June 2010

AbstractIf the Baker‐Venkataraman rearrangement of C‐methylphloracetophenone triaroyl esters is carried out in DMSO with powdered NaOH, the result greatly depends on the substitution pattern both of the phloracetophenone moiety possessing either one or two C‐methyl groups and of the aroyl parts bearing a conjugated methoxy group (or not such a group) with respect to the carbonyl group. With benzoyl, 4‐methoxybenzoyl or 3,4‐dimethoxybenzoyl as aroyl group the 3,5‐dimethylphloracetophenone triaroyl esters 10a–c directly yield the corresponding unsubstituted ring B or 4′‐methoxy‐ and 3′,4′‐dimethoxy‐substituted 5,7‐dihydroxy‐6,8‐dimethylflavones 11a–c. In contrast, the 3‐methylphloracetophenone triaroyl esters 3a–c react quite differently, depending on the aroyl substitution pattern. Thus, the triester 3a containing benzoyl groups gives the hemiketal Wessely‐Moser isomers 5a, 5a′ whereas the triesters 3b and 3c containing 4‐methoxy‐ or 3,4‐dimethoxybenzoyl groups are converted into compounds existing as two equilibria of two β‐diketo and two β‐keto enol tautomers. Finally, dehydration of each mixture furnishes solely the corresponding unsubstituted ring B or 4′‐methoxy‐ and 3′,4′‐dimethoxy‐substituted 5,7‐dihydroxy‐6‐methylflavones 8a–c. Methylation of 11c affords 7‐O‐methyl and 5,7‐di‐O‐methyl derivatives 12a and b.
Alkylations of Chiral Imidazolidinones Derived from Di‐ and Triglycine and Attempts at Cyclisations to Give Cycloisodityrosines
Authors: Bezencon Olivier , Seebach Dieter 
Published: June 2010

AbstractDi‐ and triglycine derivatives (1–5) containing a 2‐tert‐butyl‐1,3‐imidazolidin‐4‐one moiety were prepared in rac. and enantiopure forms. By deprotonations with LiNR2 these imidazolidinones were converted to Li, Li2, and Li3 derivatives (H‐N) and the latter alkylated, preferably with the more reactive electrophiles (MeI, benzylic and allylic bromides). The diastereoselectivity at the endocyclic (imidazolidinone) position is always very high (>95:5), while it varies with respect to the newly formed stereocentres at the exocyclic positions (2:1 to >95:5). Three dozens of new di‐ and triglycine derivatives were thus prepared and fully characterised. Cyclisation attempts with seven different diaryl ethers (23, 29, 32, 35, 39, 44, 45), which are potential precursors of cycloisodityrosines, failed. The configurations of the products were assigned by X‐ray structure analysis (29, 40, 53), NMR analysis, and hydrolysis to the amino acid components, followed by GC analysis.
Preparation of 12‐ and 16‐Membered Macrolactones (Oligolides) from (S)‐Malic Acid – Low Molecular‐Mass Analogs of the Biopolymer Poly[(S)‐Malic Acid] (PMA)
Authors: Hoffmann Torsten , Seebach Dieter 
Published: June 2010

AbstractAs model compounds of uniform composition for the biopolymer PMA, 12‐ and 16‐membered oligolides derived from malic acid by esterification between the carboxylic acid and the β‐hydroxy groups were prepared (Schemes 1 and 2). A reduced form of the triolide derivatives 2, 4, the tris(hydroxymethyl) triolide 10, was also synthesized (Scheme 3). The macrocyclic compounds were isolated in up to 60% yield and fully characterized. The water‐soluble tri‐ and tetracarboxylic acids of this type, thus available for the first time, will be studied as potential binders to polycationic biomolecules.
New Synthetic Routes to 2‐Fluoro‐2‐phenylalkanoic Acids
Authors: Goj Olav , Haufe Günter 
Published: June 2010

Abstract2‐Fluoro‐2‐phenylalkanoic acids 2 are obtained by oxidation of the corresponding β‐fluoro‐β‐phenyl alcohols 6. These compounds are shown to be accessible by two alternative pathways, either by bromo fluorination of α‐alkyl styrenes 3, subsequent bromine‐by‐acetate replacement in the bromo fluorides 4 and hydrolysis of the acetates 5 or by a BF3 · OEt2 catalyzed ring opening of corresponding styrene oxides 8 with triethylamine tris(hydrofluoride).
[2 + 1] Cycloaddition Reaction of Dialkylthioketenes with Carbenes – Isomerization of the Resulting Alkylidenethiiranes
Authors: Behr Helmut , Bolte Oliver , Dräger Gerald , Ries Monika , Schaumann Ernst 
Published: June 2010

AbstractCarbenes generated by metal‐catalyzed decomposition of diazo compounds 2 undergo a smooth cycloaddition to the CS bond of thioketenes 1; products 3 were characterized by spectroscopic means as well as an X‐ray structural investigation of 3b. However, photolytic generation of diphenylcarbene from diphenylketene led to an isomeric alkylidenethiirane 4a in the reaction with di‐tert‐butylthioketene (1a). Analogously, alkylidenethiiranes 3a, b, d, g, h could be photoisomerized to isomers 4a, b, d, g, h. The corresponding rearrangement of S‐oxides 8 afforded isomers 9.
AnomericO‐Alkylation, 15. New 2/1‐Type Surfactants by AnomericO‐Alkylation of Mannofuranose
Authors: Terjung Andreas , Jung Karl‐Heinz , Schmidt Richard R. 
Published: June 2010

AbstractNew 2/1‐type surfactants were synthesized from glycerol derivatives2a–ehaving a long‐chain 2‐O‐alkyl substituent. Transformation of2a–dinto 1,3‐di‐O‐trifluoromethanesulfonates4a–dand their use in anomericO‐alkylation of mannofuranose7afforded after protective group removal β‐linked bis‐mannofuranosides13a–d. Preparation of mono‐O‐benzyl‐protected compounds5b–efrom2b–e, trifluoromethyanesulfonate formation, and then anomericO‐alkylation of7gave afterO‐debenzylation 1‐O‐mannofuranosides10b–e. Their unprotected 3‐hydroxy group was employed for the attachment of a β‐glucopyranosyl residue (→15b–e) and a sulfate group (→18b–e). Transformation of10b–einto alkylating agents19b–eand20b–e, respectively, enabled the attachment of the malonate group (→17b–e), oligoethylene glycol residues (→28b–e, 29b–e, 30b–e), iminodiacetic acid (→32b–e), and of the aspartate residue (→34b–e) as second hydrophilic group. Surface tension (σs) and critical micelle concentration (cmc) measurements with these compounds are reported and the results discussed.
Targeting RNA with Conformationally Restricted Oligonucleotides
Authors: Herdewijn Piet 
Published: June 2010

AbstractA configurational and conformational complementarity between targeted ssRNA and the antisense oligonucleotide is a prerequisite for efficient hybridization. In the design of oligonucleotides that may hybridize strongly with natural RNA, one may select molecules with a preorganized structure. The hybridization process should then benefit from less negative entropy changes during duplex formation. Although, it is by now not completely clear which conformational restricted motif is best suited for this purpose, the N3′–P5′ phosphoramidate linkage and the hexitol nucleic acids seems to gain the objective.