关键词： 丁酸酯   二苯基   不对称合成   氧代   非对映异构体   苯乙烯基   苯乙酸酯   化学产率   手性醇   反应   催化   铜盐   吗啉   重氮   产物  

摘要： 手性醇衍生的α-重氮苯乙酸酯与N-(苯乙烯基)-吗啉在铜盐催化下的反应,能够以高度的化学产率制备手性的4-氧代-2,4-二苯基-丁酸酯,产物中两种非对映异构体的比例达到2:1.

关键词： β-氨基酸   β-氨基酸衍生物   α-重氮羰基化合物   合成方法   不对称合成  

摘要： β-氨基酸衍生物通常是具有重要的生物活性的，存在于许多天然产物中。因此，β-氨基酸衍生物引起了化学工作者的广泛关注。特别是β-氨基酸衍生物的不对称合成已经成为有机化学家的挑战课题。尽管已经有许多关于不对称合成β-氨基酸衍生物的方法，但是每种方法都有其优点和缺点。因此发展新合成方法，并研究新型化合物的性质是非常有意义的工作。\n 我们发现相对稳定的α-重氮羰基化合物可以与N-对甲苯磺酰基亚胺缩合得到具有β-氨基酸骨架结构的化合物。我们的研究建立在此基础之上。本文研究了α-重氮膦酸酯与N-对甲苯磺酰基亚胺的缩合反应以及缩合反应产物的反应性质。碱促进下的缩合产物重氮分解反应，催化氢化还原反应，可以转化为β-氨基酸的-类重要衍生物：α-芳基-β-氨基膦酸酯类化合物。缩合产物也可经过氧化还原转化为β-氨基亚膦酸酯类化合物。我们发现由方便易得的原料重氮乙酸甲酯和N-对甲苯磺酰基亚胺经三步反应可以高非对映选择性的得到α-羟基β-氨基酸酯。首先，α-重氮乙酸甲酯与亚胺在碱促进下发生缩合反应。然后，缩合产物由非常便宜的氧化剂Oxone()氧化得到羰基化合物。最后，经NaBH4还原得到反式α-羟基β-氨基酸酯，经Pd/C(10％)催化氢化得到顺式α-羟基β-氨基酸酯。我们发现了第一例碱促进下的由重氮化合物衍生的阴离子与亚胺的非对映选择性加成反应。加成产物可以保持新手性中心构型不发生变化而转化为具有光学活性的重氮甲酯类化合物。我们进一步将此重氮化合物应用于α-羟基β-氨基酸酯的不对称合成中。\n 最后，讨论了研究过程中的部分尝试性工作，总结了从中获取的信息。

关键词： cyclopropylphosphonic acids   copper catalysts   ruthenium catalysts   cyclopropanation   diazo reagents  

摘要： The transition metal- catalyzed cyclopropanation of alkenes using alpha- diazomethylphosphonates leads to cyclopropylphosphonate derivatives in high yields. The reaction proceeds well with copper, rhodium, and ruthenium catalysts. The best catalysts for the enantioselective version are either Evans' Cu center dot bis( oxazoline) or Nishiyama's Ru center dot pybox.

关键词： GLUCOSE-DEHYDROGENASE GENES   BIOCATALYTIC REDUCTION   ALCOHOLS  

摘要： An efficient fedbatch process for the production of Lactobacillus kefir DSM 20587 cells was developed. An improvement in space time yield of 270% ( 3.7 g(DCW) l(-1)-day(-1)) and in final enzyme activity of 440% (9.1 U/ml) was achieved on a 150 l scale by controlling the oxygen transfer rate to 7 - 9 mmol l(-1) h(-1). The cells exhibited good and highly stereoselective reducing activities against tert-butyl 6-chloro-3,5-dioxohexanoate. tert-Butyl (3R, 5S)-6-chlorodihydroxyhexanoate,a chiral building block for HMG-CoA reductase inhibitor synthesis, was produced with 47.5% yield and > 99% ee at C(3)3 and C(5)5 in a simple batch biotransformation process.

关键词： Ligands   Stereoselectivity   Enantioselective synthesis   Catalysts   Aromatic compounds  

摘要： Rhodium-catalyzed asymmetric 1,4-addition of arylboronic acids to coumarins proceeded with high enantioselectivity in the presence of a rhodium catalyst (3 mol %) generated from Rh(acaC)(C2H4)(2) and (R)-Segphos to give the corresponding (R)-4-arylchroman-2-ones in over 99% ee. This asymmetric reaction was applied to the synthesis of (R)-tolterodine.

关键词： Alkynes/chemical synthesis   Animals   Catalysis   Esters/chemical synthesis   Ketones/chemistry   Porifera/chemistry   Vinyl Compounds/chemistry  

摘要： The asymmetric construction of tertiary alcohols is a continuing *** particular,catalytic and asymmetric C-C bond reactions on ketones are difficult due to theirlower reactivity and lesser steric dissimilarity compared to that of ***-branchedaliphatic ketones are particularly challenging substrates where the catalyst needs to discriminatebetween a methyl and a methylene ***,efficient enantioselective addition oforganometallics (mainly zinc alkylation,zinc arylation,zinc vinylation,zinc alkynylation,tin andboron allylations) to ketones to form tertiary alcohols has been described.

关键词： 手性叔胺   单一型催化剂   复合型催化剂   L-脯氨酸   α-苯乙胺   双活化   不对称合成   不对称Baylis-Hillman反应  

摘要： 从便宜易得的手性源L-脯氨酸、α一苯乙胺出发合成了七种手性叔胺并将它们作为催化剂应用到不对称Baylis-Hillman反应中。存各种不同的溶剂体系中，首先研究了它们作为单一型的催化剂对不对称Baylis-Hillman反应的对映选择性的影响：其次，采用双活化的先进理念，研究了这些手性叔胺与会属络合物、L-脯氨酸相结合作为复合型催化剂对不对称Baylis-Hillman反应对映选择性的影响，并取得了比较好的不对称诱导效果。其中，手性叔胺N-甲基-N-α-苯乙胺-2-环己醇、三环苯并二氮杂类化合物、氯酶胺在单独不能催化不对称Baylis-Hillman反应的情况下，与L-脯氨酸结合作为复合催化剂后不仅能够催化这个反应，而且在CHCl<,3>／THF体系中，催化邻硝基苯甲醛与甲基乙烯基酮的反应，得到的相应产物的ee值最高分别达到81.2％、 82.7％、81.

关键词： lignans   nucleophilic acylation   alpha-amino nitriles   Michael addition   circular dichroism  

摘要： The first asymmetric synthesis of a lignan isolated from the seeds of Virola sebifera, one of the most widely spread Myristicaceae species in Brazil, in four steps (48 % overall yield) and with excellent stereoselectivity (de, ee >= 96 %) is described. The key step is the asymmetric Michael addition of a lithiated enantiopure alpha-amino nitrile to an enone, followed by a-methylation and cleavage of the amino nitrile. The absolute configuration of the naturally occurring 1,4-diketone was determined by polarimetry as well as by CD spectroscopy and quantum chemical calculations. ((c) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)

关键词： Ethers   Organic compounds   Molecular structure   Ketones   Enantioselective synthesis  

摘要： The asymmetric synthesis of both enantiomers of cis-lauthisan (3) is achieved in only six steps from diethyl pimelate (4), the key steps being the diastereodivergent reduction of beta-ketosulfoxide 7 and the highly cis-stereoselective Et3SiH/TMSOTf-promoted reductive cyclization of enantiopure hydroxy sulfinyl ketones (S)-14 and (R)-14.

关键词： Catalysis   Esters/chemical synthesis   Ethylenes/chemistry   Ferrous Compounds/chemistry   Ferrous Compounds/chemistry   Ketones/chemistry   Stereoisomerism  

摘要： During the past several years,we have established that planar-chiralheterocycles,such as 1-5,serve as enantioselective catalysts for an array of processes,includingkinetic resolutions of alcohols and amines,C-acylations that generate all-carbon quaternarystereocenters,and coupling reactions of *** part of these studies,in 1999,we reported thatazaferrocene 1 catalyzes the addition of MeOH to aryl alkyl ketenes (eq 1).Although theenantioselectivity is only moderate (up to 80% ee),this is the most effective catalytic asymmetricmethod for the synthesis of esters from ketenes that has been described to date.