关键词： oxabicyclo[3.2.1]octadiene   absolute configuration   asymmetric synthesis   crystal structure  

摘要： The compound under investigation crystallizes in the noncentrosymmetric orthorhombic space group P2(1)2(1)2(1) with a = 7.9358(11), b = 11.0532(13), c = 29.2425(43) Angstrom, volume = 2565.0(6) Angstrom(3), and Z = 4. The C23H34O8Si molecule contains three chiral centers tone of which is of known configuration, based upon an (R)-pantolactone auxiliary group). We have determined the absolute configuration of this species (via the anomalous dispersion of Si relative to C and O) and show that it is consistent with the known configuration of the (R)pantolactone moiety.

关键词： Oxides   Reaction products   Inhibitors   Inhibition   Conformation  

摘要： Using the catalytic asymmetric Sharpless carbamate aminohydroxylation, conformationally restricted L-arginine and L-homoarginine derivatives (5-8) were prepared in good enantiomeric excess to investigate the binding requirements of L-arginine-based compounds with nitric oxide synthase. The L-arginine derivatives (5 and 6) inhibited both the inducible and neuronal isoforms of nitric oxide synthase with little isoform selectivity (5, IC50 = 42 and 144 mu M, 6, 8 and 12 mu M, respectively). The guanidine-containing compound (5) did not act as a nitric oxide producing substrate for nitric oxide synthase. The ability of these compounds to interact with the enzyme supports the idea that L-arginine-based inhibitors bind to the enzyme in a folded conformation. The L-homoarginine derivatives (7 and 8) did not interact with the enzyme as either substrates or inhibitors. The two-carbon L-arginine homologue (9), prepared from L-phenylalanine, demonstrated the greatest isoform selective inhibition of the compounds examined (IC50(iNOS) = 19 and IC50- (nNOS) = 147 mu M, IC50(nNOS)/IC(50)i(NOS) = 7.7). These results suggest isoform selective inhibition may be related to the folded conformations required for binding of these higher L-arginine homologues.

关键词： Reagents   Oligomerization   Stereoselectivity   Addition reactions   Molecular structure  

摘要： Describes the use of chiral N-sulfinyl auxiliaries for the activation of glyoxylate sulfinimines toward regioselective attack by organometallic reagents. Asymmetric synthesis of alpha-amino acid derivative from N-sulfinylimino esters; Mediated condensation of (S)-(+)-p-toluenesulfinamide; Preparation of amino acid derivatives using Grignard/dialkylzinc reagents.

关键词： Anions   Cyclization   Enantioselective synthesis   Substituents   Molecular structure  

摘要： The asymmetric synthesis of 1,2-diamino-4,5-dimethylcyclohexanes was achieved by the zirconium-catalyzed and -promoted reductive cyclization of N,N'-di[(S)-1-phenylethyl]-4(R),5(R)-diamino-1,7-octadiene. The reaction of the diene with 5 equiv of butylmagnesium chloride and 0.1 mol % of bis(cyclopentadienyl)zirconium dichloride in diethyl ether at 0-20 degrees C gave mainly the 1(R),2(R)-diamino-4(S),5(S)-dimethylcyclohexane derivative having Ct symmetry, but the reaction with 4 equiv of dibutylzirconocene in tetrahydrofuran at -78 to -50 degrees C gave prevalently the diastereomer with the 4(R),5(S) configuration. By reductive cleavage of the auxiliary, followed by sulfonylation reaction, 1(R),2(R)-di(4-toluenesulfonyl)amino)-4(S),5(S)-dimethylcyclohexane was prepared.

关键词： 碱性阴离子交换树脂   苯硫酚   αβ-不饱和羰基化合物   聚合物支载的手性相转移催化剂   不对称合成   聚合物硒试剂   卤化反应  

摘要： 1.总结了碱性阴离子交换树脂在有机合成上的应用,并在此基础上以Amberlite--IRA--400(Cl型)树脂为原料制备出一系列强碱阴离子交换树脂,并用以催化苯硫酚与α、β--不饱和羰基化合物的加成反应;2.将辛可宁、奎宁生物碱支载在氯甲基化的苯乙烯--二乙烯苯共聚物上制备出二种具有手性中心的聚合物相转移催化剂,用于诱导N--二苯基甲叉基甘 氨酸叔丁酯与不同烷基化试剂反应,室温下合成出具有一定光学活性的a-发基酸,这是一种利用相转移催化剂不对称合成a-氨基酸的新方法;3.总结了聚合物硒试剂在有机合成上的应用,在此基础上合成了一种聚合物硒试剂,并用于卤化反应.

关键词： 手性乙二胺   不对称合成   化学酶   氧化偶联   联萘酚  

摘要： 由天然易得的(L)-麻黄素(1a0)和(D)-伪麻黄素(1b0)合成了两个系列的手性乙二胺(2和3).2和3的结构经<\'1>HNMR、<\'13>CNMR和MS确证.2和3的配合物被作为化学酶(chemical enyme,chemzyme)用于催化2-萘酚类化合物的不对称氧化偶联反应.2为N-羟乙基手性乙二胺,其铜配合物(2·Cu(OH)Cl)不能催化2-萘酚类化合物的氧化偶联.实验表明,由于反应过程中生成了稳定的2·Cu(OH)Cl·联萘酚类化合物的配合物,催化剂不能再生,氧化耦联反应终止.3的铜配合物催化的2-萘酚类化合物的氧化偶联反应可以高产率地得到联萘酚类化合物(>90%).实验表明:1.在不同的反应溶剂中反应速度变化很大,但反应溶剂对产物的产率和光学纯度影响不大;2.3·Cu(OH)Cl和3·CuCl<,2>均能催化2-萘酚类化合物的氧化偶联.但3·Cu(OH)Cl催化的反应的产物具有较好的光学纯度;3.具有较大位阻的3的铜配合物(3·Cu(OH)Cl)催化3-羟基-2-萘甲酸酯类(5和6)能得到较好光学活性的产物,其中3b3·Cu(OH)Cl催化6的结果最好(9,ⅰaⅱ<,589\'20>+104.84,THF,c=1).综上所述,配合物3·Cu(OH)Cl催化2-萘酚类化合物的氧化耦联反应;产物的光学活性与底物的结构、手性胺3的结构及酮·手性胺配合物的其它配体等因素有关.

关键词： 综述   不对称合成   苯乙醇胺类药物   合成  

摘要： 关于苯乙醇胺类药物不对称合成方法的综述。

关键词： 异紫草素类化合物   不对称合成   抗肿瘤活性  

摘要： 环异紫草素易由异紫草素与路易斯酸作用制备,到目前为止,尚未有关于它的不对称合成和生物活性的报道.他们探索出了一条简单,实用的全合成路线,成功地得到了光学活性的环异紫草素.以对-二甲氧基苯为起始原料,关键中间体24可以通过五步常规反应制得.研究显示,一些鞣花鞣质能抑制HIV逆转录酶和DNA拓扑异构酶Ⅰ介导的DNA松驰,其中chebulagic acid还是迄今报道的最强的DNA拓扑异构酶Ⅰ的抑制剂.且它们的活与六羟基联苯二甲酴功能基相关.他们试图利用oxazoline介导的分子间不对称Ullmann反应来完成s-HHDP基团的不对称合成,但未获成功.应用仿生合成方法,得到了消旋的保护HHDP结构.将此基团引入具生理活性的化合物分子中可能会提高它们的抗肿瘤作用.

关键词： 光学活性   氰醇   不对称合成   动力学   拆分   合成  

摘要： 光学活性氰醇是合成大量医药、农药产品的重要中间体。本文介绍了通过生物或化学催化剂进行外消旋底物的拆分或前手性底物的不对称化来制备光学活性氰醇的方法,重点讨论了有较大发展前景的有机溶剂中脂肪酶催化氰醇酯的动力学拆分的方法。

关键词： 桃潜蛾   昆虫性信息素   不对称合成  

摘要： (-)-莰烷磺内酰胺手性助剂与巴豆酸酰氯作用生成N-反式丁烯酰基衍生物(4),进而与n-C_4H_9MgBr进行Michael加成反应,发现在CuBr·Me_2S存在下,产物以S构型为主,且化学产率明显提高。经六步合成了桃潜蛾性信息素(S)-14-甲基-1-十八碳烯(1)及其对映异构体(R)-1。