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1.
-(N-Sulfonylamino)alkyl phosphites, which are intermediate products in the reactions of the corresponding hydroxy derivatives with diethyl phosphorochloridite, undergo in situ phosphorotropic rearrangement to give C-phosphorylated products. 相似文献
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In previous work from our laboratory, we demonstrated that α-carbonyl radical cyclization reactions can serve efficiently as key steps in total synthesis of natural products.1 In this presentation,we report the total synthesis of (-)-α-pinguisene from enone 1 via α-carbonyl radical cyclization. 相似文献
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Zusammenfassung Basenkatalysierte Kondensation von 4-Nitrobenzaldehyd mit Dichloracetonitril in Methanol lieferte ein als Methyliminoäther aufgefaßtes Kondensationsprodukt, dessen salzsaure Hydrolyse die im Titel genannte Säure ergab. Sie erwies sich als völlig ident mit einem Präparat, das in einer vorigen Arbeit durch Hydrolyse des 2-[-(4-Nitrophenyl)--oxy-,-dichlormethyl]-oxazolin erhalten wurde. 相似文献
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《Tetrahedron: Asymmetry》1999,10(4):679-687
Kinetic resolution of 1,1,1-trifluoro-2-alkanone cyanohydrin acyl derivatives with Candida rugosa lipase afforded the remaining (R)-enantiomer in high selectivity (E from 30 to >200). Candida rugosa lipases from several suppliers were compared and found to differ remarkably in their selectivity. The (R)-enantiomer was hydrolyzed in one step to yield optically pure (R)-α-trifluoromethyl-α-hydroxycarboxylic acids in excellent yield. The (S)-acids were obtained in good e.e. by subtilisin-catalyzed resolution of the corresponding racemic esters followed by chemical hydrolysis of the remaining (S)-esters. 相似文献
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(R)-α-硫辛酸可用于预防和治疗糖尿病及相关并发症,也可以作为保健品使用,用途广泛,因而其高效合成方法长期以来受到广泛关注。 目前,合成(R)-α-硫辛酸的方法主要有酶和化学方法催化的不对称合成、消旋体的手性拆分以及手性底物控制的不对称合成。 本文将以此为分类标准,对目前所报道的(R)-α-硫辛酸合成方法进行总结归纳和展望。 相似文献
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Diethyl (E)-α-triphenylstannyl or (Z)-α-tri-n-butylstannyl α-alkenylphosphonates are conveniently and stereoselectively prepared using a “tin-Peterson-like” reaction. Protonolysis of the carbon-tin bond of α-tributylstannyl derivatives proved to be easy and stereospecific. 相似文献
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《中国化学快报》1997,(1)
Thesynthesisofopticallyactivecompoundsisanimportantissueinmodemorgan-icchendstry-7-Terpineol,anaturalproductisolatedfrompetitgrainoil,longleafpineoi1andcaeputoill'J,hasbeenasynthetictargetduringthecourseofourstudiesontheasymmetriccatalisedDiels-AlderreactionlvInthispaper,l-phenylsulfOnyl-3-buten-2-one(l)wasusedasthesulfOnyl-functionalizedche1atingenoneforthesynthesischiral2-Terpineol(5)byaasymmetriccata1isedDiels-Alderreaction.TherouteforthesynthesisofopticallyaCtivea-Terpineo1(5)isshownin… 相似文献
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《Journal of carbohydrate chemistry》2013,32(1-2):99-111
An efficient synthesis of NeuAcα-(2→3)-Galβ-(1→3)-[NeuAcα-(2→6)]-GalNAcα1- O-(Z)-Serine (N-protected MUC II oligosaccharide–serine, 14) by a chemoenzymatic strategy is described. The enzymatic reaction of GalNAcα1- O-(Z)-Ser- OAll 7 with pNP-β-Gal in the presence of recombinant β1,3-galactosidase from Bacillus circulans gave Galβ-(1→3)-GalNAcα1- O-(Z)-Ser- OAll 3 in 68%. The introduction of two sialic acids into 3 was accomplished by a stepwise method. The branched Galβ-(1→3)-[NeuAcα-(2→6)]-GalNAcα1- O-(Z)-Ser- OAll 11 was constructed by a chemical method. Sialylation at the C-3 position of the terminal Gal residue on Galβ-(1→3)-[NeuAcα-(2→6)]-GalNAcα1- O-(Z)-Serine 2 using α2,3-(O)-sialyltransferase from rat liver gave a target compound 14 in a practical yield. 相似文献
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《Tetrahedron: Asymmetry》2001,12(6):949-957
This report describes the synthesis of enantiomerically pure (S)- and (R)-α-methylserines on a multigram scale, starting from the Weinreb amide of 2-methyl-2-propenoic acid and using a stereodivergent synthetic route that involves a Sharpless asymmetric dihydroxylation reaction. As a synthetic application of these quaternary α-amino acids, they were used as starting materials in the synthesis of the well-known valuable homochiral (S)- and (R)-N-Boc-N,O-isopropylidene-α-methylserinal building blocks. 相似文献
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(-)-10-表-α-莎草酮(1)广泛用做合成多种稠环倍半萜的手性起始原料,该化合物的合成研究早已引起广泛关注,目前虽有多种合成方法,但存在一些问题有待解决,如:立体选择性不好[1]、需要手性胺和EVK[2]等昂贵的试剂,增加了反应成本,不利于大量制备.近期我们小组以价廉易得的(+)-二氢香芹酮和丙烯酸甲酯为起始原料经四步反应,高产率、高立体选择性的得到了(-)-10-表-α-莎草酮.并对关环反应进行了深入研究,提高了反应收率[3].这是对前人合成方法的一个重要改进.具体的合成路线如Scheme 1所示. 相似文献
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《Tetrahedron: Asymmetry》1999,10(23):4619-4626
Racemates of cis- and trans-2-(Nβ-t-butoxycarbonyl-Nα-methylhydrazino)cyclopentanols and -cyclohexanols 1–4 were resolved through lipase PS- or Novozym 435-catalysed asymmetric acylation of the secondary OH group at the (R)-stereogenic centre. High enantioselectivity (E >200) was observed when vinyl acetate or vinyl butyrate was used in diisopropyl ether, resulting in the enantiopure hydrazino esters 1a–4a and hydrazino alcohols 1b–4b. Methanolysis of the esters 1a–4a afforded the corresponding 2-hydrazinocycloalkanols 1c–4c (ee usually >95%). 相似文献
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15-甲基前列腺素是具有高度生物活性的一组前列腺素类似物。15-甲基PGF_(2α)则是其中比较稳定的一个。以前我们曾经报导过一种合成此化合物的新方法。经过几年来的临床试用证明:此化合物是一种安全、有效的中期引产药物,而用于抗早孕效果也达90%以上,付作用也较小,能为使用者接受。特别是在家畜繁殖方面,用来治疗奶牛持久黄体、促使(黄、水)牛同步发情,在国内大部分省市试用都取得了令人满意的结果,一股只需要肌肉注射1~2毫克即有效。这对促进我国畜牧业的发展起到了一定的积极作用。 相似文献
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测定了新合成的α位取代和β位取代的四-(4-吡啶氧基)酞菁锌配合物的UV-Vis吸收光谱、荧光光谱及激发单重态寿命、纳秒瞬态吸收光谱与激发三重态寿命.在此基础上,与相关配合物进行了比较,探讨了取代基及其取代位置对酞菁锌配合物的吸收光谱、激发单重态寿命及激发三重态寿命的影响. 相似文献
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The synthesis of various types of optically active α-(allenylsilane-containing)glycines via a chirality-transferring ester-enolate Claisen rearrangement of α-acyloxy-α-alkynylsilanes is described. The conversion of the rearranged products into the optically active silicon-free α-(allenyl)- and α-substituted-α-(allenyl)glycines was achieved by the removal of the Me2PhSi- or TMS group from the allene terminus. 相似文献
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I. L. Lysenko A. V. Bekish O. G. Kulinkovich 《Russian Journal of Organic Chemistry》2002,38(6):875-879
Reaction of ethyl N-benzhydrylpipecolinate with ethylmagnesium bromide in the presence of catalytic amount of titanium(IV) isopropoxide furnished in a high yield the corresponding hydroxypropyl-substituted piperidine that by treating with alcoholic alkali was quantitatively converted into 1-benzhydryl-2-propionylpiperidine. The reduction in the latter of carbonyl group with lithium aluminum hydride or sodium borohydride in methanol gave rise prevailingly to threo-aminoalcohol. With sodium borohydride in the presence of cerium chloride an erythro-aminoalcohol was the main product. Deprotection of the nitrogen atom from the benzhydryl group of the aminoalcohols obtained provided racemic - and -conhydrines. 相似文献