关键词： Allyl Compounds/chemical synthesis*   Catalysis   Esters/chemical synthesis*   Palladium/chemistry   Stereoisomerism   Trichloroacetic Acid/analogs & derivatives*   Trichloroacetic Acid/analogs & derivatives*   Trichloroacetic Acid/chemistry   Trichloroacetic Acid/chemistry  

摘要： Chiral allylic alcohols and their derivatives are important intermediates inthe synthesis of many biologically active *** most widely used method to prepare 1-alken-3-ols,or their ester derivatives,in high enantiomeric purity is by kinetic *** enantioselective approach involves formation of the ***-metal-catalyzed allylic substitution has been used to prepare enantioenrichedallylic ethers from the reaction of achiral allylic carbonates with phenox-ides4 or aliphaticalkoxides,5 although these products are not readily converted into the corresponding enantioenrichedallylic *** this communication,we report the first catalytic asymmetric synthesis of3-acyloxy-l-alkenes,products readily transformed to enantioenriched allylic alcohols.

关键词： 3-AMINOPYRIDINE-2-CARBOXALDEHYDE THIOSEMICARBAZONE 3-AP   DIELS-ALDERREACTIONS   INTEGRIN RECEPTOR ALPHA(V)BETA(3)   PALLADIUM-CATALYZED ARYLATION   CROSS-COUPLINGREACTIONS   INVERSE ELECTRON DEMAND   CYCLIC ACID ANHYDRIDES   VITRONECTIN RECEPTOR   BONE-RESORPTION   ANNULATED PYRIDINES  

摘要： [GRAPHICS] The development of a practical and highly convergent synthesis of an alpha(v)beta(3) antagonist is described. The two key fragments present in this compound, a tetrahydropyrido[2,3-b]azepine ring system and a chiral 3-aryl-5-oxopentanoic acid, were constructed independently and then coupled at a late stage using a Wittig reaction. The pyridoazepine moiety was prepared from N-Boc 6-chloro-2-aminopyridine via directed ortho-metalation/alkylation followed by in situ cyclization. A Suzuki reaction was then used to attach the propionaldehyde side-chain required for Wittig coupling. The coupling partner was prepared from asymmetric methanolysis of a 3-substituted glutaric anhydride followed by elaboration of the acid moiety to the requisite beta-keto phosphorane. Using this route, kilogram quantities of the desired drug candidate were prepared.

关键词： Diols   Chemical structure   Absolute configuration   Enantioselective synthesis  

关键词： Alcohols   Aldehydes   Mixtures   Oxidation   Molecular structure  

摘要： (S,S)-Reboxetine was synthesized stereospecifically in 30% overall yield and 99% ee in eight steps. Key steps were selective oxidation of an N-protected hydroxymethylmorpholine and aryl-chromium-mediated aromatic nucleophilic substitution.

关键词： Crystallography, X-Ray   Furans/chemical synthesis*   Norbornanes/chemistry*   Norbornanes/radiation effects   Photochemistry   Stereoisomerism  

摘要： Solution-phase irradiation of a series of syn-7-benzoylnorbornene derivatives is shown to lead to cis-fused dihydrofuran derivatives in low quantum but excellent chemical yields in what is formally a retro-Claisen rearrangement. In analogy to the well-known Paterno-Buchi reaction, the first step of the rearrangement is suggested to involve (n,pi*)(3)-mediated addition of the carbonyl oxygen to the norbornene double bond, producing a triplet 1,4-biradical. This intermediate, rather than closing to the oxetane, undergoes cleavage accompanied by intersystem crossing to form the dihydrofuran. To determine whether the retro-Claisen photorearrangement could be carried out enantioselectively, the 7-benzoylnorbornene reactant was equipped with a para-carboxylic acid substituent to which a series of optically pure amines was attached ionically via salt bridges. Irradiation of these salts in the crystalline state followed by diazomethane workup (the solid-state ionic chiral auxiliary method) was shown to afford the corresponding dihydrofuran in optical yields as high as 93% at 95% conversion. X-ray crystallography revealed that the enantioselectivity arises from crystallization of the reactant in a conformation in which the carbonyl oxygen is more favorably oriented for bond formation to one end of the norbornene double bond than the other, thus leading to a predominance of a single enantiomer.

关键词： 烷氧基   呋喃酮   反应性   不对称合成   手性化合物   基团   位置   Michael加成   环加成  

摘要： 总结了近年来一类具有γ-烷氧基-2(5H)-呋喃酮结构的手性化合物的合成,反应性的研究进展,主要包括Michael加成、环加成、对γ位置的亲核进攻以及此手性建构基团在不对称合成中的应用.

关键词： L-脯氨酸   手性β-氨基醇   不对称合成   氨基保护   格氏反应  

摘要： 目的:合成一组具有重要用途的光学活性β 氨基醇. 方法:以手性天然产物L 脯氨酸为原料经酯化、氨基保护、格氏反应和催化氢解等四步反应合成四种光学活性的β 氨基醇. 结果:从原料L 脯氨酸到目标分子,四步总产率46%. 产物的1HNMR和元素分析结果与结构和元素组成相符. 结论:该方法原料价廉易得,反应条件温和,操作简便,产率高. 为合成手性β 氨基醇类化合物提供了一条有效途径.

关键词： 可回收配体   不对称二羟化   手性连二醇   不对称合成   烯烃  

摘要： 用 1,4 二氟蒽醌与奎宁 (QN)反应可高收率地得到 1,4 双 (9 O 奎宁 )蒽醌 ((QN) 2 AQN) ,再经OsO4氧化可得到带有 4个羟基的手性配体 .在不对称二羟化反应的 2种不同体系中 ,该配体对 6种烯烃的反应表现出很高的对映选择性 (80 %～97% )和催化活性 (80 %～ 94 % ) .该配体不但具有金鸡纳生物碱衍生物小分子配体优异的立体选择性 ,同时也能象高聚物负载的大分子配体一样能够回收和重复使用 ,而且用量少 ,活性高 ,后处理简单 .在以反式肉桂酸乙酯为底物的不对称二羟化反应中 ,在t BuOH H2 O/K3 Fe(CN) 6体系中循环使用 5次 (配体平均回收率 93% ) ,在Me2 CO H2 O/NMO(N 甲基 N 氧吗啉 )体系中循环使用 8次 ,配体的催化活性和对映选择性基本保持不变 .

关键词： 手性药物   不对称催化   合成  

摘要： 结合实例就催化不对称合成的两种方法应用于手性药物合成作简要概述。外消旋体拆分、化学计量不对称合成和催化不对称合成是利用化学手段获得手性药物的 3种方法 ,其中催化不对称合成法是最经济有效地合成手性药物的方法 ,它又可分为化学催化不对称合成法和酶催化不对称法。

关键词： 手性相转移催化剂   手性季铵盐   L-(-)-色氨酸   不对称合成   不对称诱导效应  

摘要： 以L -(-) -色氨酸为原料,经酯化、季铵化合成了4种手性季铵盐,以L -色氨酸甲酯为原料,经还原、季铵化合成了2种手性季铵盐;6种手性季铵盐对苯甲醛与氯仿的亲核加成反应,显示出良好的相转移催化作用和一定的不对称诱导效应.