Enzymatic synthesis of both enantiomeric forms of 3-allyloxy-propane-1,2-diol
摘要:
The stereoselective synthesis of (S)- and (R)-3-allyloxy-propane-1,2-diol has been accomplished in four steps from (RS)-3-allyloxy-propane-1,2-diol. Only one intermediate, namely 1-benzoyloxy-3-allyloxy-2-propanone has been prepared by a chemical reaction, that is, pyridinium chlorochromate oxidation of 1-benzoyloxy-3-allyloxypropan-2-ol. All of the remaining reactions (regioselective acylations, asymmetric bioreduction of prochiral ketones, and enzymatic alcoholysis) have been carried out in the presence of biocatalysts. (C) 2012 Elsevier Ltd. All rights reserved.
A concise synthesis of a plasmenylethanolamine (PlsEtn-[16:0/18:1 n-9]), known as antioxidative phospholipids commonly found in cell membranes, has been achieved from an optically active known diol through 8 steps. The key transformations for the synthesis of PlsEtn-[16:0/18:1 n-9] are (1) regio- and Z-selective vinylether formation via the alkylation of a lithioalkoxy allyl intermediate with an alkyl
Asymmetrical ester derivatives of 1,4-dihydrophyridine-3,5-dicarboxylic
申请人:Fournier Innovation et Synergie
公开号:US04806544A1
公开(公告)日:1989-02-21
The present invention relates to novel asymmetrical esters derived from 1,4-dihydrophyridine-3,5-dicarboxylic acid, of the formula: ##STR1## in which: R.sub.1 represents a C.sub.1 -C.sub.4 alkyl group, R.sub.2 represents a C.sub.1 -C.sub.4 alkyl group, a benzyl group, a benzoyl group or a phenyl group optionally substituted by one or more C.sub.1 -C.sub.4 alkoxy, C.sub.1 -C.sub.4 alkyl, cyano, nitro, hydroxyl or trifluoromethyl groups or by one or more halogen atoms, and R.sub.3 and R.sub.4, which are identical or different, each represent the hydrogen atom, a nitro group or a chlorine atom, their optical isomers and diastereoisomers and also the corresponding addition salts. These novel esters are useful in therapy, especially as antihypertensives.
Heterobimetallic dual-catalyst systems for the hydrolytic kinetic resolution of terminal epoxides
作者:Xiang Hong、Mohamed Mellah、Emmanuelle Schulz
DOI:10.1039/c4cy00235k
日期:——
rate-determining step, which supported a heterobimetallic highlyenantioselectivepathway based on the crucial existence of in situ generated CoIII-OH species, previously postulated in the literature. The beneficial effect of the presence of additional Mn-complexes was ascribed to the inhibition of the alternative less enantioselective monometallic reactionpathway by epoxide activation.
已经开发了一种基于多种萨伦配合物的制备和使用的异双金属双催化剂体系,用于末端环氧化物的水解动力学拆分(HKR)。由具有噻吩或吡咯部分的相同构型的配体产生的钴-钙铝和锰-钙铝配合物的组合确实产生了用于表溴醇水解的高度选择性的催化剂。这种作用还可以扩展到其他末端环氧化物和环己烯氧化物更具挑战性的开环。动力学研究表明,速率测定步骤仅涉及一种Co III salen络合物,它基于原位生成的Co III的关键存在,支持了一种异双金属的高对映选择性途径。-OH物种,以前在文献中已假定。额外的锰配合物的存在的有益作用归因于通过环氧化物活化抑制替代性的较少对映选择性的单金属反应途径。
Synthesis of glucosylphosphatidylglycerol via a phosphotriester intermediate.
作者:C.A.A. van Boeckel、J.H. van Boom
DOI:10.1016/s0040-4039(01)95462-0
日期:1979.1
Complete deblocking of a fully-protected intermediate, which was prepared by using inter alia a selective protection of 1- or 3-0-allyl-sn-glycerol with one pivaloyl group and effective phosphorylation and coupling procedures, afforded glucosylphosphatidylglycerol.
Symmetry-Assisted Synthesis of <i>C</i><sub>2</sub>-Symmetric <i>trans</i>-α,α‘-Bis(hydroxymethyl)pyrrolidine and -piperidine Derivatives via Double Sharpless Asymmetric Dihydroxylation of α,ω-Terminal Dienes
A new strategy has been developed for the synthesis of C-2-symmetric trans-alpha,alpha'-bis(hydroxymethyl)pyrrolidine and piperidine derivatives 1-3 starting from symmetric alpha,omega-terminal dienes 4-6. The double-asymmetric dihydroxylation (AD) reaction of 4-6 gave C-2-symmetric tetrols, which were converted in a four-step sequence to C-2-symmetric azacycloalkanes 17, 9, and 22, respectively. These azacycloalkanes were transformed into 1-3 in high enantiomeric excess (82% --> 98%ee). The double AD reaction proved to cause enantiomeric enhancement, even though the asymmetric induction for the first AD reaction is moderate. In addition, it was observed that the chromatography on silica gel of several C-2-symmetric azacycloalkanes (17, 20, and 22) of varying ee's resulted in marked enantiomeric fractionation.