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1.
A stereoselective synthesis of rel-(6S,7S,8S) -7-butyl-8-hydroxy-1-azaspiro[5.5]undecan-2-one, a key intermediate for the synthesis of perhydrohistrionicotoxin, was described.  相似文献   

2.
An efficient synthesis of stereodefined hydroxyethylamine dipeptide isosteres has been developed, utilizing a syn-selective Grignard addition and reductive amination as the key reactions.  相似文献   

3.
Recently we have reported a novel class of tetrahydrofuran phosphonates of which trans guanine nucleotide analog 1a showed potent antiviral activity as well as antitumor activity. In this paper we describe a stereoselective route where the key step involves an iodoetherification of a α-hydroxyphosphonate to generate the trans tetrahydrofuran with high stereoselectivity. The same intermediate 2 was also used to access the key intermediate for the cis analog 1b.  相似文献   

4.
Isoflavans have gained considerable interest owing to their potential health benefits. Herein, we have presented a straightforward strategy for isoflavans synthesis. The strategy features an intermolecular [Cu]-catalyzed arylation of malonates and an intramolecular [Pd]-catalyzed Buchwald coupling of hydroxy tethered bromoarenes as the key transformations. This protocol enabled the synthesis of a variety of isoflavan analogs.  相似文献   

5.
Thermal treatment of Zn(NH3)(4)2+ precursor in ethanol solvent led to the formation of the tubular ZnO which exhibited strong ultraviolet photoluminescence around 385 nm at room temperature; TEM images showed the hollow tubules with approximately 450 nm in diameter and approximately 4 microns in length were built up by ZnO polycrystals.  相似文献   

6.
The direct Bargellini condensation of coumarins involving reaction with chloroform and acetone in the presence of aqueous sodium hydroxide furnished o-carboxyvinylphenoxyisobutyric acids in good yields. The utility of this new useful protocol was demonstrated by the transformation of the three diesters 9b, 9f and 9g to the sesquiterpenes helianane 4, heliannuol A 2 and heliannuol C 3, respectively.  相似文献   

7.
8.
The first synthetic approach towards the Gliomasolide A is described in 15 linear steps with 4% overall yield. The key steps in this approach are RCM protocol for the construction of 14-member macrolide, a Sharpless kinetic resolution, Keck and Brown’s allylations for the installation of desired stereocenters.  相似文献   

9.
The tin-mediated 6-exo-trig radical cyclization of the acetylenic β-alkoxy acrylates proceeded smoothly to give fully substituted tetrahydropyrans in good yields with high equatorial selectivity irrespective of the stereochemistry of the propargylic position.  相似文献   

10.
A short and stereoselective route to the trans-hydrindane derivative, a potential building block for the synthesis of steroidal and related molecules, was achieved by the operation of indium, tin, and ruthenium based reagents, starting from a tetrabromo norbornyl derivative.  相似文献   

11.
12.
A scalable synthetic route towards a chiral 2,2,6-trisubstituted chiral morpholine, which is a known opioid antagonist, was developed. The synthetic route involves incorporating an aryl group via Suzuki-Miyaura coupling and stereoselective hydroalkoxylation catalyzed by trifluoromethanesulfonic acid. Late stage incorporation of both the aryl and N-alkyl groups make this route suitable for further SAR studies on this molecule.  相似文献   

13.
Enantiopure cis-2-phenyl-3-piperidinol is a commonly used synthon for the obtention of a potent class of neurokinin substance P receptor antagonists. Starting from (R)-phenylglycine, the present report describes an efficient route for the stereoselective synthesis of the above piperidinol structural core.  相似文献   

14.
A family of substituted 1,2,4-benzothiadiazine 1-chlorides have been prepared by treatment of N-arylamidines in neat thionyl chloride at reflux. The S(iv) 1-chlorides are readily reduced under mild conditions to persistent 1,2,4-benzothiadiazinyl radicals which have been characterised by EPR spectroscopy and cyclic voltammetry. Crystallographic studies on isolated radicals indicate that the radicals dimerise via pancake bonding in the solid-state, resulting in spin-pairing and net diamagnetism.

A family of 1,2,4-benzothiadiazinyl radicals are accessible from 1,2,4-benzothiadiazine 1-chlorides which can be prepared in a single step by treatment of N-arylamidines in neat thionyl chloride at reflux.  相似文献   

15.
Bis-tetrahydrofurans 1a and 1b, containing four chiral centers, are obtained with a 90 % isomeric purity from geranyl and neryl chlorides in four steps including two stereoselective cyclizations.  相似文献   

16.
We developed a novel and convenient stereoselective path for the preparation of pyrrolo-1,5-benzoxazepinones (PBOs). This innovative route envisaged the employment of (−)-menthol as convenient chiral auxiliary and a key SNAr for the stereoselective preparation of a tertiary aryl–alkyl ether. As a further advancement, we exploited this newly conceived synthetic route for the preparation of 2-substituted PBO analogues to either undergo biological evaluation themselves or give access to a variety of further functionalization options.  相似文献   

17.
《Tetrahedron: Asymmetry》2006,17(23):3294-3299
A highly efficient, consecutive approach for the construction of synthetically valued, enantiomerically pure, trisubstituted THF domains 310 in a stereoselective manner starting from glycal derived allylic alcohols 1a1d under Sharpless asymmetric epoxidation (SAE) conditions is reported. The reaction involves the intramolecular asymmetric ring opening (ARO) of in situ formed enantiopure 2,3-epoxy alcohols followed by protection of the diol.  相似文献   

18.
The stereoselective synthesis of tetracyclic intermediate, the indoline spiroaminal 3 for neoxaline (1) and oxaline (2), has been accomplished. The key step of the stereoselective synthesis of 3 was the Lewis acid mediated transcyclization of 4 to the diaminal 18, and the tungstate-catalyzed oxidation of 18 to obtain the nitrone 19, which easily cyclizes to the indoline spiroaminal framework 3. [structure: see text]  相似文献   

19.
20.
[reaction: see text] A chemo- and stereoselective palladium-catalyzed amination of silylated butenediol dicarbonates has allowed for the introduction of a glycine moiety to obtain a desired functionalized epoxysilane. A stereoselective aldolization then delivered the piperidine ring which may be used as a precursor for the synthesis of a variety of polyhydroxylated azasugars. This efficient approach has been illustrated by the synthesis of 1-deoxymannojirimycin including a stereoselective reduction with LAH and a Tamao-Fleming oxidation of a C-SiMe(2)Ph bond.  相似文献   

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