共查询到20条相似文献,搜索用时 62 毫秒
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可生物降解高分子的酶法合成和改性 总被引:10,自引:0,他引:10
介绍了新型功能高分子材料-可生物降解高分子材料的研究概况,并重点评述了这一领域研究的新分支-酶法合成可生物降解高分子材料的新进展。 相似文献
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光学活性环氧化物的酶催化合成 总被引:1,自引:0,他引:1
光学活性环氧化物的酶催化合成①夏仕文尉迟力沈润南李树本②(中国科学院兰州化学物理研究所羰基合成与选择氧化国家重点实验室,兰州730000)关键词光学活性环氧化物酶催化不对称合成动力学拆分1前言光学活性环氧化物含有两个手性碳,通过选择性开环和官能团转换... 相似文献
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Srinivas Gangula Chandrashekhar R. Elati Satish Varma Mudunuru Anitha Nardela Ashok Dongamanti Apurba Bhattacharya 《合成通讯》2013,43(15):2254-2268
Syntheses of all eight enantiomerically pure diastereomers of aprepitant and assignment of absolute configuration at newly generated stereocenters by NMR and x-ray crystallographic analysis were achieved. 相似文献
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Alexander Stoye Gabriele Quandt Björn Brunnhöfer Dr. Elissavet Kapatsina Julia Baron André Fischer Markus Weymann Dr. Horst Kunz Prof. Dr. 《Angewandte Chemie (International ed. in English)》2009,48(12):2228-2230
An animalic note : The first total synthesis of the all‐cis nupharamine 2 , an alkaloid from beaver castoreum, is based on the stereoselective domino Mannich–Michael reaction of N‐galactosylfurylaldimine to give 1 (Piv=pivaloyl), subsequent conjugate cuprate addition, and stereoselective protonation of the enolate. These reactions are all controlled by the carbohydrate. Protonation of the enolate after cleavage of the auxiliary leads to epimer 3 .
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Prof. Dr. Gerhard Bringmann Dr. Narasimhulu Manchala Dr. Tobias Büttner Dr. Barbara Hertlein‐Amslinger Raina Seupel 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(28):9792-9796
The first regio‐ and stereoselective total synthesis of the axially chiral 7,3′‐coupled naphthylisoquinoline alkaloids ancistrocladidine ( 1 ) and ancistrotectorine ( 2 ) has been described. Both possess a 7,3′‐coupled axis, which before now, was difficult to attain synthetically. Moreover, target 2 has a sensitive relative cis‐array of the two methyl groups at C1 and C3 in the tetrahydroisoquinoline part. The key step in the chosen strategy was the construction of the biaryl axis in accordance with the “lactone method”: the two molecular halves, which were activated in an “inverse‐halogenated” form, were prefixed by an ester bridge, followed by intramolecular coupling, and atroposelective cleavage of the lactone auxiliary bridge delivered the desired biaryl scaffold. 相似文献
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Yarram Narasimha Reddy Tenkayala Navya Kumari Pradeepkumar Thota Perla Jyothi Ajay Kumar Gupta 《Tetrahedron letters》2018,59(2):160-162
A new chemoenzymatic route for the preparation of cryptocaryalactones natural products using a kinetic resolution process as the key step is described. Novozyme-435 catalyzed hydrolysis of the prochiral (±)-monoester 7 afforded the precursors of cryptocaryalactones with high enantiomeric excess and excellent yields. The compounds (4S,6S)-7 and (4R,6R)-7 were converted to (+)-(6R,2′S)-cryptocaryalactone (1) and (?)-(6S,2′R)-cryptocaryalactone (2), respectively by employing Wittig-olefination, lactonization and acylation reactions. 相似文献
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N-硬脂酰基亮氨酸的合成 总被引:3,自引:0,他引:3
采用酰氯化反应与缩合反应两步法合成N -硬脂酰基亮氨酸。以硬脂酸和亚硫酰氯为原料 ,n(硬脂酸 )∶n(亚硫酰氯 ) =1∶1 .5 ,在 80℃下冷凝回流 6h酰氯化反应合成硬脂酰氯 ,硬脂酰氯经减压蒸馏收集 1 70~2 0 0℃的馏分得到。硬脂酰氯收率为 65 %。硬脂酰氯再与亮氨酸的氢氧化钠溶液在冰水浴中进行Schotten -Baumann缩合反应制得N -硬脂酰基亮氨酸。缩合反应最佳工艺条件是反应溶液pH值控制为 9.0。反应后滴加1mol/L盐酸至pH =5 .0~ 6.0 ,加入正己烷使N -硬脂酰基亮氨酸处于水层中 ,分离并蒸干水层溶液得含NaCl的混合物。用无水乙醇萃取混合物 ,萃取液蒸干得产物。N -硬脂酰基亮氨酸收率为 75 % 相似文献
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Summary. (R,6R,7R)-7-(1-Acetoxyethyl)-3-methyl-2-isoxacephem-4-carboxylic acid and its enantiomer have been prepared. The ring systems were formed from the corresponding enantiomerically pure N-unsubstituted -lactams. The reduction of methyl [(R,2S,3R)-3-(1-acetoxyethyl)-1-(4-methoxyphenyl)-4-oxoazetidine-2-carboxylate] has been solved via a hemi-acetal. The structure and the configuration of a new stereogenic center in this intermediate was predicted by using 2D NMR technique and unambiguously proven by x-ray. 相似文献
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Zsuzsanna Sánta József Nagy László Párkányi József Nyitrai 《Monatshefte für Chemie / Chemical Monthly》2004,42(3):671-684
(R,6R,7R)-7-(1-Acetoxyethyl)-3-methyl-2-isoxacephem-4-carboxylic acid and its enantiomer have been prepared. The ring systems were formed from the corresponding enantiomerically pure N-unsubstituted -lactams. The reduction of methyl [(R,2S,3R)-3-(1-acetoxyethyl)-1-(4-methoxyphenyl)-4-oxoazetidine-2-carboxylate] has been solved via a hemi-acetal. The structure and the configuration of a new stereogenic center in this intermediate was predicted by using 2D NMR technique and unambiguously proven by x-ray. 相似文献
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Wilko Greschner Beate Neumann Dr. Hans‐Georg Stammler Prof. Dr. Harald Gröger Prof. Dr. Dietmar Kuck 《Angewandte Chemie (International ed. in English)》2015,54(46):13764-13768
Inherently chiral acetophenones and benzaldehydes bearing the large, bowl‐shaped framework of tribenzotriquinacene (TBTQ) were synthesized in enantiomerically pure form employing enzyme catalysis. Five‐step sequences involving lipase CAL‐B lead to the (M)‐enantiomers, (+)‐2‐acetyl‐TBTQ (M)‐ 5 and (+)‐2‐formyl‐TBTQ (M)‐ 6 , whereas use of lipase PS leads to the (P)‐enantiomers, (?)‐2‐acetyl‐TBTQ (P)‐ 5 and (?)‐2‐formyl‐TBTQ (P)‐ 6 , with at least 99 % ee in each case. The absolute configuration of these rigid 3D building blocks was determined by X‐ray diffraction analysis of the ketones 5 and by comparison of their chiroptical properties with those of the aldehydes 6 . 相似文献
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Lisa K. Thalén Dongbo Zhao Dr. Jean‐Baptiste Sortais Dr. Jens Paetzold Dr. Christine Hoben Dr. Jan‐E. Bäckvall Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(14):3403-3410
Dynamic transformation : A racemization catalyst and the enzyme Candida antarctica lipase B (CALB) were combined in a one‐pot dynamic kinetic resolution (DKR) of primary amines, which were transformed to their corresponding amides in up to 95 % yield and >99 % ee. This chemoenzymatic DKR was also applied to the synthesis of norsertraline (see scheme).