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1.
(R)-螺[4,5]癸-2,7-二酮的合成 总被引:3,自引:1,他引:3
从环己烯酮出发,经手性催化的Michael加成反应,Wolff重排反应延长碳链, 再利用重氮化合物的C-H插入反应,以8步反应28.5%的总收率合成了手性β,β '-螺二酮.在合成路线中手性中心的构型保持不变.在最后的检测中未发现另一对 映体,开始产生的手性中心在合成过程没有消旋化。 相似文献
2.
Jiu Yu LIU Hui Yuan GUO* Institute of Medicinal Biotechnology Chinese Academy of Medical Sciences Peking Union Medical College Beijing 《中国化学快报》2004,15(5)
Quinolone antibacterial agents have emerged as one of the dominant classes chemotherapeutic drugs for the treatment of various bacterial infections1. We have focused our attention on the modification of the C-7 basic group of the quinolone which has been most varied. In 1987, Uno et al.2 reported that 3-hydroxypyrrolidine quinolones showed more active antibacterial activities than Norfloxacin in vivo. In 1998, Fujita et al.3 reported that 2-aminomethylpyrrolidine quinolones have the same … 相似文献
3.
Sim TB Kang SH Lee KS Lee WK Yun H Dong Y Ha HJ 《The Journal of organic chemistry》2003,68(1):104-108
5-Funtionalized enantiomerically pure oxazolidin-2-ones were prepared in one pot from commercially available chiral aziridines bearing an electron-withdrawing group at C-2 with retention of the configuration in high yields by regioselective aziridine ring-opening followed by intramolecular cyclization. 相似文献
4.
Starting from 2-cyclopentenoyl chloride ((RS)- or (S)- 8 ), the racemic as well as the enantiomerically pure (+)-sesquiterpenes longifolene ((±)- and (+)- 1 , resp.) and sativene ((±)- and (+)- 2 , resp.) were synthesized efficiently by a sequence of nine and ten steps, respectively. The key sequence 10 → 16 → 3 is the first strategic application of an intramolecular photoaddition/retro-aldolization sequence (intramolecular de Mayo reaction) in organic synthesis. 相似文献
5.
Aart Molenberg Daniela Michalke Martin Mller Thomas Pieper 《Journal of polymer science. Part A, Polymer chemistry》1998,36(1):169-177
Poly[(S)-(+)-2-methylbutyl]pentylsiloxane has been synthesized by anionic ring opening polymerization of the corresponding strained cyclic trisiloxane with cryptated lithium (Li+/[211]) as counterion. The polymer did not show the low and high temperature crystalline phases, that are generally found for poly(di-n-alkylsiloxane)s. Instead, the material formed a hexagonal columnar mesophase until it melted around 400°C. MAS and solution 13C- and 29Si-NMR, polarizing microscopy and WAXS indicated an unexpectedly regular chain structure. It was tentatively concluded that the steric interaction of the (S)-(+)-2-methylbutyl side chains introduces sufficient regularity of the tacticity and that the chains tend to adopt a defect helix conformation. On the other hand, DSC showed the presence of a glass transition at −113°C, indicating a high flexibility of the backbone. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 169–177, 1998 相似文献
6.
Ethyleneglycol derivatives of 2-methyl (and ethyl)-3-hydroxy-4-pyridinone were synthesized by a modified Hilbert-Johnson reaction. The synthesis proceedes by reaction of O-protected 2-alkyl-3-hydroxy-4-pyridinone with hexamethyldisilazane in the presence of chlorotrimethylsilane followed by trimethylsilyl trifluoromethanesulfonate catalized alkylation with benzyloxy-ethoxymethylchloride in dichloroethane and deprotection by hydrogenation. The overall yield was 87%. This method provides a useful way to produce oligo- or polyethyleneglycol substituted hydroxypyridinones. 相似文献
7.
Several N-[(2-alkoxycarbonyl)benzoyl]-4-hydroxyisoxazolidines were prepared as the racemic mixtures, and resolved by the lipase-mediated acylation. 相似文献
8.
Hironao Sajiki Karen Y. Ong Samuel T. Nadler Heather E. Wages Thomas J. McMurry 《合成通讯》2013,43(13):2511-2522
A convenient synthesis of enantiomerically enriched 1-hydroxymethyl-DTPA (diethylenetriamine pentaacetic acid) penta-t-butyl esters 3 has been achieved for the preparation of chiral synthones of new paramagnetic gadolinium complexes. 相似文献
9.
《Comptes Rendus de l''Academie des Sciences Series IIB Mechanics Physics Astronomy》1998,1(11):709-714
The preparation and the crystal structure of the title compound are described. C6H5CH[NHCOOC(CH3)3]CH2OH is monoclinic with the following unit-cell dimensions: a = 10.354(2), b = 6.533(3), c = 10.505(1) Å, β = 98.58(1)∘. The space group is P21 and Z = 2. The crystal-structure determination was run by using 1481 independent reflexions with a final R value of 0.033 (Rw = 0.043). 相似文献
10.
The straightforward, high‐yield synthesis and X‐ray structural analysis of the air‐stable planar‐chiral bis(ferrocenyl)carbene 1,3‐bis‐{(1R)‐1‐[(1R)‐1‐(trimethylsilyl)ferrocen‐2‐yl]ethyl}imidazol‐2‐ylidene ( 5 ) is reported. Compound 5 is obtained in four steps from the amine [(1R)‐1‐(dimethylamino)ethyl]ferrocene ( 1 ) upon diastereoselective silylation, methylation, nucleophilic substitution by imidazole, and deprotonation. The X‐ray crystal structure of the free carbene shows the typical conformational features of the 1,2‐disubstituted ferrocenyl units, as found in other ferrocenyl ligands derived from 1 . 相似文献
11.
N-Methyl-N-[(1S)-1-[(3R)-pyrrolidin-3-yl]ethyl]amine (1)(1) is a key intermediate in the preparation of premafloxacin (2), which was under development as an antibiotic for use against pathogens of veterinary importance. This paper describes the development of a practical, efficient, and stereoselective process for the preparation of 1 from isobutyl (3S)-3-[methyl[(1S)-1-phenylethyl]amino]butanoate (5c). The key steps in the synthetic sequence are an asymmetric Michael addition, which yields 5c, and a stereoselective alkylation, which yields (3S,4S)-3-allyl-1,4-dimethylazetidin-2-one (17). 相似文献
12.
(R)- and (S)-α-ionone ((R)- and (S)- 1 , resp.) were prepared from (R)- and (S)-α-damascone ((R)- and (S)- 3 , resp.) without racemization in 48% yield employing a new enone transposition. The described transposition is complementary to existing methods whose application is often prohibited by the structural requirements of the substrate. The now easily accessible α-ionones of desired absolute configuration are useful as chiral building blocks for terpenoid synthesis. 相似文献
13.
14.
Yuji Ogawa Yushun Fujishima Hideharu Ishida Makoto Kiso Akira Hasegawa 《Journal of carbohydrate chemistry》2013,32(5):643-652
ABSTRACT Lipid A subunit analogs, the 4-O-phosphono-D-glucosamine derivatives (14-16: GLA 93-95) which carry 2-N-linked 3-hydroxyacyl groups, were synthesized. 2-(Trimethylsilyl)ethyl 2-amino-2-deoxy-4,6-O-isopropylidene-ß-D-glucopyranoside (1) was transformed into 2-(trimethylsilyl)ethyl 2-amino-6-O-tert-butyldimethylsilyl-2-deoxy-4-O-diphenylphosphono-3-O-[(3R)-3-tetradecanoyloxytetradecanoyl]-ß-D-glucopyranoside (7) through several steps. N-Acylation of 7 with 3-hydroxyl fatty acids gave the corresponding 8-10, which were converted, via the cleavage of protecting groups, into a series of desired compounds. 相似文献
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16.
ZHANG Shuo WANG Wenjin LI Chuan LIU Peng XU Weiren TANG Lida WANG Jianwu ZHAO Guilong 《高等学校化学研究》2014,30(2):250-256
A facile 7-step procedure for the synthesis of enantiomerically pure 1-(5-bromo-2-chlorophenyl)-1-(4-ethoxyphenyl)ethanes[(R)-2 and(S)-2] that started from (5-bromo-2-chlorophenyl)(4-ethoxyphenyl)methanone 3 was developed.The key step was the resolution of 2-(5-bromo-2-chlorophenyl)-2-(4-ethoxyphenyl)acetic acid 6 by crystallizations of its L-and D-menthyl esters 7 and 8 from petroleum ether to give optically pure enantiomers 9 and 10,respectively.The absolute configurations of the products were unambiguously determined by single-crystal X-ray diffractions of four key intermediates,9,10,13 and 14.This procedure is characterized by inexpensiveness,scalability and ability to produce two individual enantiomers of a diarylethane with unambiguously determined absolute configurations and high enantiomeric purities. 相似文献
17.
Jean-Michel Adam Lon Ghosez Kendall N. Houk 《Angewandte Chemie (International ed. in English)》1999,38(18):2728-2730
An asymmetric allylmetalation followed by a silicon-stereodirected cycloaddition gives enantiomerically pure bicyclic compounds. The synthesis of enantiopure 1 (see scheme) in a yield of 65–74 %, 93 % ee, and >98 % de provides an illustration of the efficacy of the method. The preferential formation of 1 rather than its diastereoisomer (32:1), during the cycloaddition step, matches the result predicted by RHF and density functional theory studies. 相似文献
18.
19.
The synthesis of a novel tris(bidentate ligand)ruthenium(II) complex 7 and its efficient tethering to the 5′-end of Oligonucleotides is described. The resulting Δ- and Δ-isomeric ruthenium(II)-labelled Oligonucleotides 10a--c and 11a--d were separated either by reversed-phase HPLC or by polyacrylamide gel electrophoresis. The diastereoisomerically pure isomers were fully characterized by UV/VIS and CD spectroscopy, mass spectrometry, and enzymatic digestion with base analysis. We also investigated the thermal denaturation of the hybridized double strands. 相似文献