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11.
Nucleobase‐anion glycosylation of 2‐[(2‐methyl‐1‐oxopropyl)amino]imidazo[1,2‐a]‐1,3,5‐triazin‐4(8H)‐one ( 6 ) with 3,5‐di‐O‐benzoyl‐2‐deoxy‐2‐fluoro‐α‐D ‐arabinofuranosyl bromide ( 8 ) furnishes a mixture of the benzoyl‐protected anomeric 2‐amino‐8‐(2‐deoxy‐2‐fluoro‐D ‐arabinofuranosyl)imidazo[1,2‐a]‐1,3,5‐triazin‐4(8H)‐ones 9 / 10 in a ratio of ca. 1 : 1. After deprotection, the inseparable anomeric mixture 3 / 4 was silylated. The obtained 5‐O‐[(1,1‐dimethylethyl)diphenylsilyl] derivatives 11 and 12 were separated and desilylated affording the nucleoside 3 and its α‐D anomer 4 . Similar to 2′‐deoxy‐2′‐fluoroarabinoguanosine, the conformation of the sugar moiety is shifted from S towards N by the fluoro substituent in arabino configuration. 相似文献
12.
Lhiaubet-Vallet V Sarabia Z Boscá F Miranda MA 《Journal of the American Chemical Society》2004,126(31):9538-9539
A remarkable stereodifferentiation has been observed in the interaction between the excited triplet state of carprofen (CP) and human serum albumin (HSA). Time-resolved measurements using laser flash photolysis reveal the presence of two components with different lifetimes in triplet decay. This is explained by complexation of CP to the two possible HSA binding sites. The shorter-lived components are ascribed to the CP/HSA complexes in site I, where stereodifferentiation is more important (tauR/tauS ca. 4). This is correlated with formation of a dehalogenated photoproduct upon steady-state photolysis. 相似文献
13.
7-deaza-2,8-diaza-2'-deoxyadenosine (4) was synthesized from 8-aza-7-deaza-2'-deoxyadenosine (1) via the 1,N(6)-etheno derivative 5. Ring opening with sodium hydroxide followed by ring closure in the presence of sodium nitrite formed the tricyclic intermediate 5 from which the transiently introduced "etheno" moiety was removed with NBS. Compound 4 was converted to the phosphoramidite 11, which was employed in solid-phase oligonucleotide synthesis. Base pairing studies on 4, incorporated in a 12-mer duplex, showed that this adenine nucleoside analogue forms a strong base pair with dG but not with dT. This novel base pair is as stable as that of the canonical dA-dT pair. As a result of the absence of nitrogen-7 compound 4 is expected to form a face to face base pair with dG. 相似文献
14.
Montaignac B Praveen C Vitale MR Michelet V Ratovelomanana-Vidal V 《Chemical communications (Cambridge, England)》2012,48(52):6559-6561
Enantioselective metallo-organocatalyzed carbocyclizations of formyl-alkynes have been developed. The cooperation between aminocatalysis and a chiral copper(I) complex granted access to enantio-enriched cyclopentanes through the challenging formation of all-carbon quaternary stereocenters. 相似文献
15.
Virginie Blot Jean-François Brièr Marion Davoust Stéphanie Minière Vincent Reboul Patrick Metzner 《Phosphorus, sulfur, and silicon and the related elements》2013,188(5-6):1171-1182
Abstract Our work on the thio-Claisen rearrangement mediated by an adjacent sulfinyl group is reviewed. The substrates could easily be prepared on a large scale from diacetone-D-glucose. The rearrangement was effected with a diastereoselectivity of 95:5, in favor of the (S,S) or the (R,R) isomer. An approach to natural bis(lactones) was investigated, using a halolactonization reaction and a second [3,3] sigmatropic shift, again mediated by the sulfinyl group. The second part deals with the catalytic enantioselective benzylidenation of aldehydes, mediated by chiral sulfur ylides. We have introduced simple C 2 symmetric thiolanes for that purpose. The procedure is very practical and enantiomeric excesses up to 96% have been reported for the model of stilbene oxide. A series of ferrocenyl sulfides with planar chirality has also been investigated, leading to unexpected diastereoselectivities and enantiomeric excesses up to 94%. 相似文献
16.
Rodríguez-Muñiz GM Marin ML Lhiaubet-Vallet V Miranda MA 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(26):8024-8027
DNA damage: The reactivity of HO(.) with silylated 2'-deoxyribonucleosides was investigated in acetonitrile by means of a time-resolved technique. The obtained rate constants were in general slightly lower than those reported for the natural nucleosides in water. Analysis of the reaction mixture by UPLC-MS revealed that HO(.) attack occurred at the nucleobase (see scheme). 相似文献
17.
Maxime Guitet Pinglu Zhang Filipa Marcelo Coralie Tugny Jesús Jimnez‐Barbero Olivier Buriez Christian Amatore Virginie Mouris‐Mansuy Jean‐Philippe Goddard Louis Fensterbank Yongmin Zhang Sylvain Roland Mickaël Mnand Matthieu Sollogoub 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2013,125(28):7354-7359
18.
19.
Milway VA Niel V Abedin TS Xu Z Thompson LK Grove H Miller DO Parsons SR 《Inorganic chemistry》2004,43(6):1874-1884
The structures and magnetic properties of self-assembled copper(II) clusters and grids with the "tritopic" ligands 2poap (a), Cl2poap (b), m2poap (c), Cl2pomp (d), and 2pomp (e) are described [ligands derived by reaction of 4-R-2,6-pyridinedicarboxylic hydrazide (R = H, Cl, MeO) with 2-pyridinemethylimidate (a-c, respectively) or 2-acetylpyridine (d, R = Cl; e, R = H)]. Cl2poap and Cl2pomp self-assemble with Cu(NO(3))(2) to form octanuclear "pinwheel" cluster complexes [Cu(8)(Cl2poap-2H)(4)(NO(3))(8)].20H(2)O (1) and [Cu(8)(Cl2pomp-2H)(4)(NO(3))(8)].15H(2)O (2), built on a square [2 x 2] grid with four pendant copper arms, using "mild" reaction conditions. Similar reactions of Cl2pomp and 2pomp with Cu(ClO(4))(2) produce pinwheel clusters [Cu(8)(Cl2pomp-2H)(4)(H(2)O)(8)](ClO(4))(8).7H(2)O (3) and [Cu(8)(2pomp-2H)(4)(H(2)O)(8)](ClO(4))(8) (4), respectively. Heating a solution of 1 in MeOH/H(2)O produces a [3 x 3] nonanuclear square grid complex, [Cu(9)(Cl2poap-H)(3)(Cl2poap-2H)(3)](NO(3))(9).18H(2)O (5), which is also produced by direct reaction of the ligand and metal salt under similar conditions. Reaction of m2poap with Cu(NO(3))(2) produces only the [3 x 3] grid [Cu(9)(m2poap-H)(2)(m2poap-2H)(4)](NO(3))(8).17H(2)O (6) under similar conditions. Mixing the tritopic ligand 2poap with pyridine-2,6-dicarboxylic acid (picd) in the presence of Cu(NO(3))(2) produces a remarkable mixed ligand, nonanuclear grid complex [Cu(9)(2poap-H)(4)(picd-H)(3)(picd-2H)](NO(3))(9).9H(2)O (7), in which aromatic pi-stacking interactions are important in stabilizing the structure. Complexes 1-3 and 5-7 involve single oxygen atom (alkoxide) bridging connections between adjacent copper centers, while complex 4 has an unprecedented mixed micro-(N-N) and micro-O metal ion connectivity. Compound 1 (C(76)H(92)N(44)Cu(8)O(50)Cl(4)) crystallizes in the tetragonal system, space group I, with a = 21.645(1) A, c = 12.950(1) A, and Z = 2. Compound 2 (C(84)H(88)N(36)O(44)Cl(4)Cu(8)) crystallizes in the tetragonal system, space group I, with a = 21.2562(8) A, c = 12.7583(9) A, and Z = 2. Compound 4 (C(84)H(120)N(28)O(66)Cl(8)Cu(8)) crystallizes in the tetragonal system, space group I4(1)/a, with a = 20.7790(4) A, c = 32.561(1) A, and Z = 4. Compound 7(C(104)H(104)N(46)O(56)Cu(9)) crystallizes in the triclinic system, space group P, with a = 15.473(1) A, b = 19.869(2) A, c = 23.083(2) A, alpha = 88.890(2) degrees, beta = 81.511(2) degrees, gamma = 68.607(1) degrees, and Z = 2. All complexes exhibit dominant intramolecular ferromagnetic exchange coupling, resulting from an orthogonal bridging arrangement within each polynuclear structure. 相似文献
20.
Harrak Y Blaszykowski C Bernard M Cariou K Mainetti E Mouriès V Dhimane AL Fensterbank L Malacria M 《Journal of the American Chemical Society》2004,126(28):8656-8657
5-En-1-yn-3-ol substrates bearing a free hydroxyl group or an acyl group are highly versatile partners for PtCl2-catalyzed cycloisomerizations. Electrophilic activation of the alkyne moiety triggers at wish a hydride or an O-acyl migration yielding at the end to regioisomeric keto derivatives. The efficient preparation of Sabina ketone, an important monoterpene precursor, has been worked out. 相似文献