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1.
Graldine Calvet Nicolas Blanchard Cyrille Kouklovsky Rgis Guillot 《Acta Crystallographica. Section C, Structural Chemistry》2007,63(6):o365-o368
The crystal structures of 2,2‐dimethyl‐5‐nitroso‐1,3‐dioxan‐5‐yl benzoate, C13H15NO5, (I), 2,2‐dimethyl‐5‐nitroso‐1,3‐dioxan‐5‐yl 4‐chlorobenzoate, C13H14ClNO5, (II), and 5‐nitroso‐1,3‐dioxan‐5‐yl 4‐chlorobenzoate, C11H11NO5, (III), have been determined in order to gain insight into the conformational preference of α‐benzoyloxynitroso. Unfavourable 1,3‐diaxial interactions force (I) and (II) to crystallize in the 2,5 twist‐boat conformation, whereas compound (III), lacking this destabilizing interaction, crystallizes in the chair conformation. 相似文献
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Ivn Brito Aldo Mundaca Alejandro Crdenas Matías Lpez‐Rodríguez 《Acta Crystallographica. Section C, Structural Chemistry》2007,63(10):o606-o608
In the title disulfide, C12H8N6O2S2, all bond lengths and angles are within normal ranges, and the molecules are linked into centrosymmetric R22(20) dimers by simple C—H...N interactions. Weak intermolecular C—H...π(arene) and π–π interactions, involving the benzene CH groups and the benzene rings, and the pyridine rings, respectively, further stabilize and reinforce the crystal structure. 相似文献
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Marilyn S. Whittemore Ned D. Heindel Ivan Jabin Christophe Guillon Thomas E. Mcneel Robert D. Rapp Diane E. Heck Jeffrey D. Laskin 《Journal of heterocyclic chemistry》2001,38(4):909-916
New synthetic approaches to 4,8‐dimethyl‐5′‐(N‐pyridiniummethyl)‐4′,5′‐dihydropsoralens and 4,8‐dimemyl‐5′‐(N‐aminomethyl)‐4′,5′‐dihydropsoralens are described. The 5′‐halomethyl‐4′,5′‐dihydro‐psoralen precursors are formed by electrophilic ring closures of 4,8‐dimethyl‐6‐allyl‐7‐hydroxycoumarin. The ring‐closure reactions may also be applied to the synthesis of 5′‐halomethyl‐4‐methyl‐4′,5′‐dihydroangelicins. The compounds are potential therapeutic agents for improved psoralen ultraviolet A radiation treatment. 相似文献
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Dubravka Matkovi‐alogovi Erim Bei Kreimir Sankovi 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(9):o568-o569
The molecular structure of the title compound, also known as 2‐thiothymine [systematic name: 2,3‐dihydro‐5‐methyl‐2‐thioxopyrimidin‐4(1H)‐one], C5H6N2OS, is similar to that of thymine, with only small changes in the ring structure, apart from a significant difference at the substitution site [S=C = 1.674 (1) Å]. The molecules are connected by hydrogen bonds, with N—H?O = 2.755 (2) Å and N—H?S = 3.352 (1) Å. The hydrogen‐bond network is different from that in thymine, since it involves all the donor and acceptor atoms. 相似文献
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Frank Seela Kuiying Xu Henning Eickmeier 《Acta Crystallographica. Section C, Structural Chemistry》2005,61(6):o408-o410
In the title compound, 4‐amino‐7‐(2‐deoxy‐β‐d ‐erythro‐pentofuranosyl)‐5‐fluoro‐7H‐pyrrolo[2,3‐d]pyrimidine, C11H13FN4O3, the conformation of the glycosyl bond lies between anti and high anti [χ = −101.1 (3)°]. The furanose moiety adopts the S‐type sugar pucker (2T3), with P = 164.7 (3)° and τ = 40.1 (2)°. The extended structure is a three‐dimensional hydrogen‐bond network involving a C—H⋯F, two N—H⋯O and two O—H⋯O hydrogen bonds. 相似文献
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Vishnumurthy R. Hegde Katherine L. Seley Stewart W. Schneller 《Journal of heterocyclic chemistry》2000,37(5):1361-1362
A preparation of (1′R,2′S,3′R,4′S)‐1‐(2′,3′,4′‐trihydroxycyclopent‐1′‐yl)‐lH‐cytosine (5′‐norcarbodine, 3 ) has formally been achieved in 2 steps from (+)‐(1R,4S)‐4‐hydroxy‐2‐cyclopenten‐1‐yl acetate ( 4 ) and cytosine. The L‐like enantiomer of 3 (that is, 6 ) is also reported using the enantiomer of 4 (that is, 7 ). In evalu ating 3 and 6 for antiviral potential against a number of viruses, compound 3 was found to have activity towards Epstein‐Barr virus (EBV). 相似文献
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Frank Seela Yang He Hans Reuter Eva‐Maria Heithoff 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(8):989-991
In the title compound, 2‐amino‐1‐(2‐deoxy‐β‐d ‐erythro‐pentofuranosyl)‐5‐methylpyrimidin‐4(1H)‐one, C10H15N3O4, the conformation of the N‐glycosidic bond is syn and the 2‐deoxyribofuranose moiety adopts an unusual OT1 sugar pucker. The orientation of the exocyclic C4′—C5′ bond is +sc (+gauche). 相似文献
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Suresh Babu Meruva A. Raghunadh N. Anil Kumar U. K. Syam Kumar R. Vasu Dev P. K. Dubey 《Journal of heterocyclic chemistry》2011,48(3):540-548
A variety of 5‐aryl‐(20S)‐camptothecin derivatives were synthesized by the reaction of 5‐hydroxy‐(20S)‐camptothecin with aromatic hydrocarbons under Friedel‐Craft reaction conditions in moderate to good yield as diastereomeric pairs. The methodology was then extended for the synthesis of 5‐amido‐(20S)‐camptothecin derivatives by reacting 5‐hydroxy‐(20S)‐camptothecin with alkyl and aryl nitriles under Ritter type reaction conditions. The reaction is presumed to proceed through an iminium ion intermediate under Friedel Craft and Ritter type reaction condition, which is further trapped by nucleophile present in the reaction medium. J. Heterocyclic Chem., 00 , 00 (2011). 相似文献
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David K. Dean 《ChemInform》2002,33(40):223-223
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Kanji Kubo Emi Yamamoto Akira Mori 《Acta Crystallographica. Section C, Structural Chemistry》2001,57(5):611-613
The title compounds, 4‐hydroxy‐5‐oxo‐1,3,6‐cycloheptatriene‐1‐carbonitrile, C8H5NO2, (I), and 2‐hydroxy‐5‐nitro‐2,4,6‐cycloheptatrien‐1‐one, C7H5NO4, (II), have intra‐ and intermolecular hydrogen bonds. The structure of (II) contains two crystallographically independent molecules, (IIa) and (IIb). An intermolecular π–π interaction and an intermolecular NO2?π–π interaction are present in (I) and (II), respectively. 相似文献
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Reijo Sillanp Jordi Llop Clara Vias Francecs Teixidor Raikko Kiveks 《Acta Crystallographica. Section C, Structural Chemistry》2001,57(8):900-901
In the title compound, (η5‐2,5‐dimethylpyrrolyl)[(7,8,9,10,11‐η)‐7‐methyl‐7,8‐dicarba‐nido‐undecaborato]cobalt(III), [3‐Co{η5‐[2,5‐(CH3)2‐NC4H2]}‐1‐CH3‐1,2‐C2B9H10] or [Co(C3H13B9)(C6H8N)], the CoIII atom is sandwiched between the pentagonal faces of the pyrrolyl and dicarbollide ligands, resulting in a neutral molecule. The C—C distance in the dicarbollide cage is 1.649 (3) Å. 相似文献
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Matthew Polson Mark M. Turnbull Jan L. Wikaira 《Acta Crystallographica. Section C, Structural Chemistry》2013,69(10):1152-1156
The hydrobromide and hydrochloride salts of 2‐amino‐5‐iodopyridine were prepared from aqueous solutions. The hydrobromide salt, C5H6IN2+·Br−·0.5H2O, crystallizes as a hemihydrate, and exhibits hydrogen bonding and π‐stacking which stabilize the crystal structure. The hydrochloride salt, C5H6IN2+·Cl−·H2O·0.375HCl, crystallized as the hydrate and exhibits similar hydrogen bonding and π‐stacking in the lattice. The most interesting feature of the hydrochloride salt is the presence of an additional fractional HCl molecule which introduces disorder in the location of the water molecule. The additional proton from the fractional HCl molecule is accounted for by the presence of a partial hydronium ion on one of the water sites. 相似文献
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Thanikasalam Kanagasabapathy Panchanatheswaran Krishnaswamy Jeyaraman Ramasubbu 《Acta Crystallographica. Section C, Structural Chemistry》2009,65(11):o579-o582
rac‐5‐Diphenylacetyl‐2,2,4‐trimethyl‐2,3,4,5‐tetrahydro‐1,5‐benzothiazepine, C26H27NOS, (I), and rac‐5‐formyl‐2,2,4‐trimethyl‐2,3,4,5‐tetrahydro‐1,5‐benzothiazepine, C13H17NOS, (II), are both characterized by a planar configuration around the heterocyclic N atom. In contrast with the chair conformation of the parent benzothiazepine, which has no substituents at the heterocyclic N atom, the seven‐membered ring adopts a boat conformation in (I) and a conformation intermediate between boat and twist‐boat in (II). The molecules lack a symmetry plane, indicating distortions from the perfect boat or twist‐boat conformations. The supramolecular architectures are significantly different, depending in (I) on C—H...O interactions and intermolecular S...S contacts, and in (II) on a single aromatic π–π stacking interaction. 相似文献
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We describe the synthesis of (5′S)‐5′‐C‐butylthymidine ( 5a ), of the (5′S)‐5′‐C‐butyl‐ and the (5′S)‐5′‐C‐isopentyl derivatives 16a and 16b of 2′‐deoxy‐5‐methylcytidine, as well as of the corresponding cyanoethyl phosphoramidites 9a , b and 14a , b , respectively. Starting from thymidin‐5′‐al 1 , the alkyl chain at C(5′) is introduced via Wittig chemistry to selectively yield the (Z)‐olefin derivatives 3a and 3b (Scheme 2). The secondary OH function at C(5′) is then introduced by epoxidation followed by regioselective reduction of the epoxy derivatives 4a and 4b with diisobutylaluminium hydride. In the latter step, a kinetic resolution of the diastereoisomer mixture 4a and 4b occurs, yielding the alkylated nucleoside 2a and 2b , respectively, with (5′S)‐configuration in high diastereoisomer purity (de=94%). The corresponding 2′‐deoxy‐5‐methylcytidine derivatives are obtained from the protected 5′‐alkylated thymidine derivatives 7a and 7b via known base interconversion processes in excellent yields (Scheme 3). Application of the same strategy to the purine nucleoside 2′‐deoxyadenine to obtain 5′‐C‐butyl‐2′‐deoxyadenosine 25 proved to be difficult due to the sensitivity of the purine base to hydride‐based reducing agents (Scheme 4). 相似文献
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Xiao‐Qin Wang Jian Zhang Zhao‐Ji Li Yi‐Hang Wen Jian‐Kai Cheng Yuan‐Gen Yao 《Acta Crystallographica. Section C, Structural Chemistry》2004,60(12):m657-m658
The title compound, [Nd(C7H3O6S)(H2O)]n or [Nd(SSA)(H2O)]n (H3SSA is 5‐sulfosalicylic acid), was synthesized by the hydrothermal reaction of Nd2O3 with H3SSA in water. The compound forms a three‐dimensional network in which the asymmetric unit contains one NdIII atom, one SSA ligand and one coordinated water molecule. The central NdIII ion is eight‐coordinate, bonded to seven O atoms from five different SSA ligands [Nd—O = 2.405 (4)–2.612 (4) Å] and one aqua O atom [Nd—OW = 2.441 (4) Å]. 相似文献
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Synthesis of a DNA Promoter Segment Containing All Four Epigenetic Nucleosides: 5‐Methyl‐, 5‐Hydroxymethyl‐, 5‐Formyl‐, and 5‐Carboxy‐2′‐Deoxycytidine 下载免费PDF全文
Arne S. Schröder Jessica Steinbacher Barbara Steigenberger Felix A. Gnerlich Stefan Schiesser Toni Pfaffeneder Prof. Dr. Thomas Carell 《Angewandte Chemie (International ed. in English)》2014,53(1):315-318
A 5‐formyl‐2′‐deoxycytidine (fdC) phosphoramidite building block that enables the synthesis of fdC‐containing DNA with excellent purity and yield has been developed. In combination with phosphoramidites for 5‐methyl‐dC, 5‐hydroxymethyl‐dC, and carboxy‐dC, it was possible to prepare a segment of the OCT‐4 promoter that contains all four epigenetic bases. Because of the enormous interest in these new epigenetic bases, the ability to insert all four of them into DNA should be of great value for the scientific community. 相似文献
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Total syntheses of 5‐hexadecanolide ( 1 ), 6‐acetoxy‐5‐hexadecanolide ( 2 ) and tanikolide ( 3 ) are described. 1‐Bromoundecane ( 4 ) and 5‐benzyl‐1‐pentanal ( 5 ) were chosen as starting materials. Wittig olefination and Grignard addition 4 and 5 afforded the 16‐carbon skeleton, which under went a series of functional group transformations to give δ‐lactonederivatives 1, 2 and 3. 相似文献