关键词： Metabolism   esters   Ascorbic Acid   Biological Process   virtual instrument   Biological   Asymmetric synthesis   Hydroxyl group   acids  

摘要： Hydroxy- and aminophosphonic acids exhibit interesting biological andpharmacological properties and therefore have been intensively studied [1-3].In the present work weprepared phosphathreoninic esters V and VI and free phosphathreoninic acid VII,phosphorus analogs ofthe natural treoninic acid (threonate) which plays an important role in the metabolism of ascorbicacid and in some other biological processes.

关键词： cycloaddition   azomethine ylide   Natural products   Asymmetric synthesis   Key Transformation  

摘要： The ADE fragment of nakadomarin A has been synthesized in nine linear steps from commercial material. The key transformation is an asymmetric azomethine ylide [1,3]-dipolar cycloaddition to establish the AD-spirocyclic system containing three of the four stereocenters of the natural product.

关键词： MASKED O-BENZOQUINONES   DIELS-ALDER REACTIONS   QUINONE KETALS   2-METHOXYPHENOLS   DIENOPHILES   GENERATION  

摘要： [GRAPHICS] An asymmetric synthesis of orthoquinone monoketals was accomplished using anodic oxidation to convert aryl methyl ethers bearing a chiral ethanol unit into orthoquinone bisketals, followed by monohydrolysis of their dimethyl ketal unit. All four possible stereoisomers were generated in a diastereoselective manner by varying the attachment point of the chiral pro-ketal alcoholic auxiliary to the starting arene. A preliminary screening of subsequent nucleophilic addition reactions confirmed the potential utility of these synthons in asymmetric synthesis.

摘要： Optically active polypropionate units were synthesized in 9-11 steps from 3,5-dimethylphenol. The sequence consists of the BUchner reaction controlled by a chiral 2,4-pentanediol tether and diastereoselective hydrogenation over Raney nickel.

关键词： CARBON-PHOSPHORUS BONDS   C-H INSERTION   AZIRIDINE 2-PHOSPHONATES   ENANTIOPURE SULFINIMINES   PHOSPHONATES   ACIDS   CATALYSIS  

摘要： Cis-5-substituted pyrrolidine phosphonates, proline surrogates, are prepared by a highly stereoselective intramolecular metal carbenoid N-H insertion from a sulfinimine-derived delta-amino alpha-diazo beta-ketophosphonate.

摘要： Stereoselective allylation of camphor and subsequent terminal hydroformylation affords a new delta-lactol auxiliary (camTHP*OH) on multigram scale. Stereoselective condensation with glycine dimethylamide and Cbz protection affords a camTHP*-desymmetrized glycinamide building block which undergoes efficient and highly diastereoselective metal enolate alkylation reactions. Acid-mediated deprotection affords the N-Cbz-protected a-amino amide products which may be converted directly to alpha-amino ketones on treatment with Grignard or organolithium reagents without loss of stereochemical integrity.

关键词： PROLINE   RING formation (Chemistry)   LYSINE   GLUTAMINE   ARGININE   SERINE  

摘要： The amino-zinc-ene-enolate cyclization reaction is a straightforward route to the synthesis of 3-substituted prolines. Herein we report the application of this reaction to the syntheses of proline chimeras of lysine, glutamic acid, glutamine, arginine, and serine. All these compounds were obtained in enantiomerically pure form and suitably protected for peptide synthesis.

关键词： Oxides   Reaction products   Cyclization   Ketones   Enantioselective synthesis  

摘要： The asymmetric synthesis of a model aldehyde (2R,6R)-2 and the C32-C38 fragment of phorboxazoles, (2R,4R,6R)-1, is described using a sulfoxide as chiral auxiliary. Key advances include the stereoselective reductions of beta-keto- or beta,gamma-diketosulfoxides, the acid-catalyzed cyclization of enantiopure sulfinyl hydroxy ketone precursors to the tetrahydropyran ring, and the Pummerer reaction on the pendant sulfoxide to create the formyl group.

关键词： Alkylation   Indoles/chemical synthesis*   Physostigmine/analogs & derivatives*   Physostigmine/chemical synthesis*   Pyrrolidines/chemical synthesis*   Stereoisomerism  

摘要： A versatile route to enantiopure 3,3-disubstituted oxindoles and 3a-substituted pyrrolidinoindolines is described in which diastereoselective dialkylation of enantiopure ditriflate 10 with oxindole enolates is the central step. These reactions are rare examples of alkylations of prostereogenic enolates with chiral sp(3) electrophiles that proceed with high facial selectivity (10-20:1). The scope of this method is explored, and a model to rationalize the sense of stereoselection is advanced. This dialkylation chemistry was used to synthesize (-)-phenserine on a multigram scale in six steps and 43% overall yield from 5-methoxy-1,3-dimethyloxindole (27) and to complete a short formal total synthesis of (-)-physostigmine (2).

关键词： Didemnaketals   手性中心   非对映选择性   合成   分子内内手性诱导Julia反应   对映选择性氧化   二级醇   手性三氧化铬配合物   手性配体  

摘要： 本论文包括二个方面的工作:1.抗HIV活性海洋天然产物Didemnaketals的合成研究;在论文第一部分,我们经过大量的探索性实验,从天然(R)-(+)-长叶薄荷酮出发,经过13步反应,首次合成了Didemnaketals A C<,17>~C<,23>片段化合物(3R,4S,6R)-6-甲基-3,4-二(叔丁基二甲基硅氧基)-7-羟基-2-庚酮;从(S)-(-)-香茅醛出发,经过6步反应合成了C<,23>~C<,28>片段化合物(3S)-3-甲基-6-苯磺酰基-己酸;经部分官能团和保护基的变化和调整,通过Julia偶联烯化反应最终实现了C<,17>~C<,23>和C<,23>~C<,28>片段化合物的联结,经22步反应,合成了Didemnaketals B C<,17>~C<,28>片段化合物,(E)-(3S,8S,9S,11R)-3,7,11-三甲基-12-(叔丁基二甲基硅氧基)-9-(甲氧基甲氧基)-8-苄氧基-6-烯-十二酸甲酯.C<,17>~C<,28>片段化合物含有四个手性中心和一个三取代的反式C=C双键.整个合成策略中的关键反应包括:(1)通过分子内手性诱导,构筑了二个新的手性中心.(2)通过Julia反应构筑了三取代的反式C=C双键.其中由酮与砜构筑三取代反式C=C双键的Julia反应,在天然产物的合成中还很少有人报道.2.二级醇的对映选择性氧化研究;在第二部分,我们主要合成了一些吡啶类三级醇手性配体,并首次从反应温度、溶剂、时间几个方面考察了该类配体的三氧化铬配合物对不同种类的二级醇的对映选择性氧化方面的性能.目前,此项研究已取得了初步结果,其二级醇的对映选择性氧化ee值已达到35%.高价铬手性配合物在二级醇的对映选择性氧化方面的研究,目前尚未见报道.在整个论文研究过程中,共合成化合物116个,其中新化合物86个.这些化合物的结构经波谱测定得到确证.