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.

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： L-酒石酸   手性试剂   手性助剂   立体选择性   不对称合成   对映体   疏水性   萃取   拆分   添加剂  

摘要： 疏水性L-酒石酸正戊酯是一种拆分对映体的重要手性试剂，在手性选择体、对映体的萃取，立体选择性萃取，手性助剂不对称合成及高效液相色谱流动相添加剂等方面中的应用研究日益增多。

关键词： 噁唑啉   不对称合成   手性催化剂   金属配合物   固载   不对称反应  

摘要： 本文综述了近年来固载手性双唑啉的合成及其金属配合物作为手性催化剂在催化不对称反应中的研究进展。

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.

关键词： 不对称合成   不对称还原   生物催化   羰基还原   手性醇  

摘要： 综述了国内外利用生物催化羰基的不对称还原合成手性醇的研究情况。介绍了生物催化各类潜手性羰基化合物不对称还原的原理、菌种的筛选 。

摘要： A chiral cobalt(III) complex of a Schiff base derived from (R)-tryptophan and salicylaldehyde catalysed asymmetric trimethyl-silylcyanation of benzaldehyde at ambient temperature and a 20:1 substrate/catalyst ratio with the formation of enantiomerically enriched mandelonitrile (ee up to 77%).