浅谈有机合成路线设计

随着有机合成化学的迅速发展,新的反应、新的试剂不断涌现。选择有机合成路线成为我们研究的重要课题。 有机合成设计的任务就是找出合成目标分子的各种可能的途径,再根据原料情况,产率高低,合成步骤多少等因素,确定切实可行的一种或几种合成方法。 进行合成路线设计时,要同时考虑建立分子骨架,引入官能团和立体化学的要求。一、分子骨架的建立     

水介质中有机反应的最新研究进展

水介质中的有机反应是形成碳-碳键的有效方法之一，近几年来一直是有机合成的研究热点．本文综述了近年来对水介质中的有机反应的研究成果，包括缩合反应、亲核加成反应、环加成反应、Barbier反应和多组分反应等，及其在有机合成中的应用研究进展．     

α-季碳氨基酸的不对称催化合成

α-季碳氨基酸是一类优势骨架,广泛存在于天然产物、药物以及生物活性分子中,发展对其高效、高选择性的合成方法是现代有机合成化学的前沿研究热点.主要介绍我们小组近十年来在不对称催化合成α-季碳氨基酸中的研究进展.我们的工作主要基于以下4种策略:1)酮亚胺的不对称Strecker反应;2)α-酮酸酯衍生的酮亚胺的不对称亲核加成反应;3)前手性氧化吲哚的不对称胺化反应;4)基于α-硝基乙酸酯的不对称官能团化反应.     

功能化离子液体催化制备β-硝基苯乙烯

Henry反应是一类重要的构建碳碳键的有机反应,经缩合得到的硝基烯类化合物不仅具有杀菌、抗肿瘤活性,在有机合成中也有广泛的用途。建立了制备β-硝基苯乙烯的绿色化合成方法,采用功能化离子液体—乙醇胺乙酸盐催化硝基甲烷和苯甲醛的无溶剂反应。该方法具有高效催化、催化剂循环使用、合成绿色化等特点。将环境友好型的离子液体代替碱液应用到Henry反应中,不仅减少了废碱液的排放,而且体现了经典有机合成实验绿色化的教学理念。     

分子印迹聚合物及其有机合成中的应用

分子印迹技术是近年发展起来的一种新颖的有机合成手段。评述了分子印迹聚合物的制备方法及尚有待深入的关键问题，重点介绍了分子印迹聚合物用作催化剂在有机合成中应用的优势及研究近况，特别是用作手性催化剂不对称合成光学活性物质。并设计将分子印迹聚合物用于催化醛酮不对称还原反应，可获得较高光学产率的手性醇，其%e.e值达95%以上。     

羰基极性翻转及合成上的应用

羰基是一极性基团,在有机反应中表现为亲电性,与多种亲核试剂反应可形成碳——碳键或碳与其它原子的键,是筑成有机分子极为重要的官能团。如果它的反应性能够翻转,不仅能与亲核试剂反应,而且还能与亲电试剂反应,羰基在有机合成上的怍用将会进一步扩大.本文介绍几种使羰基极性翻转的方法及其在有机合成上的应用。     

有机膦催化炔酮分子间的环化反应研究

小分子膦催化环化反应是构建五/六元碳(杂)环的有机合成方法之一。炔酮作为缺电子反应物,可用作潜在的C2、C3、C4合成子参与环化反应,从而构建多种碳环或杂环化合物。为此,研究在叔膦催化下炔酮作为C2和C3合成子参与分子间[3+2]环化反应,生成环戊烯酮类化合物的情况。试验通过对反应催化剂、溶剂、温度及催化剂用量的考察,对反应条件进行优化。结果表明,以1,2-二氯乙烷为反应溶剂,对甲氧基三苯基膦为催化剂,在60℃条件下反应2 h,可获得良好的收率(73%)。该研究为环戊烯酮类化合物的合成提供了新方法。     

二碘化钐(SmI_2)在有机合成中的应用

二碘化钐（ＳｍＩ２）作为单电子转移试剂具有多种反应性能．并且可发生多种形成碳—碳键的新合成反应．本文就近几年二碘化钐在形成碳—碳键的有机合成中的应用进行评述．     

有机可见光催化氯代物的选择性脱氯氘化

正氘代化合物在有机合成、分析化学、药物化学等领域有着十分广泛的应用[1].近年来,随着氘代药物的兴起,发展经济高效、生命友好的氘代反应和技术备受合成化学家们的关注.药物代谢过程中,碳氢键断裂是重要步骤之一,因碳氘键比碳氢键稳定数倍,故在药物分子代谢位点引入碳氘键后可改变代谢速率,在一定程度上降低毒性、增强药性[2].传统氘化反应往往涉及过渡金属催化、苛刻反应条件或昂贵氘源等,     

含硫碳负离子──1，3－二噻烷在有机合成上的应用

对含硫碳负离子─—１，３－二噻烷的合成方法及其在有机合成上的应用进行比较系统的介绍，主要介绍１，３－二噻烷的烃基化和酰基化反应，与羰基化合物的加成反应，与氯化三甲硅的反应及１，３－二噻烷的还原反应。     

Peptide cyclization catalysed by the thioesterase domain of tyrocidine synthetase

In the biosynthesis of many macrocyclic natural products by multidomain megasynthases, a carboxy-terminal thioesterase (TE) domain is involved in cyclization and product release; however, it has not been determined whether TE domains can catalyse macrocyclization (and elongation in the case of symmetric cyclic peptides) independently of upstream domains. The inability to decouple the TE cyclization step from earlier chain assembly steps has precluded determination of TE substrate specificity, which is important for the engineered biosynthesis of new compounds. Here we report that the excised TE domain from tyrocidine synthetase efficiently catalyses cyclization of a decapeptide-thioester to form the antibiotic tyrocidine A, and can catalyse pentapeptide-thioester dimerization followed by cyclization to form the antibiotic gramicidin S. By systematically varying the decapeptide-thioester substrate and comparing cyclization rates, we also show that only two residues (one near each end of the decapeptide) are critical for cyclization. This specificity profile indicates that the tyrocidine synthetase TE, and by analogy many other TE domains, will be able to cyclize and release a broad range of new substrates and products produced by engineered enzymatic assembly lines.     

Synthesis of macrocyclic natural products by catalyst-controlled stereoselective ring-closing metathesis

Many natural products contain a C = C double bond through which various other derivatives can be prepared; the stereochemical identity of the alkene can be critical to the biological activities of such molecules. Catalytic ring-closing metathesis (RCM) is a widely used method for the synthesis of large unsaturated rings; however, cyclizations often proceed without control of alkene stereochemistry. This shortcoming is particularly costly when the cyclization reaction is performed after a long sequence of other chemical transformations. Here we outline a reliable, practical and general approach for the efficient and highly stereoselective synthesis of macrocyclic alkenes by catalytic RCM; transformations deliver up to 97% of the Z isomer owing to control induced by a tungsten-based alkylidene. Utility is demonstrated through the stereoselective preparation of epothilone C (refs 3-5) and nakadomarin A (ref. 6), the previously reported syntheses of which have been marred by late-stage, non-selective RCM. The tungsten alkylidene can be manipulated in air, delivering the products in useful yields with high stereoselectivity. As a result of efficient RCM and re-incorporation of side products into the catalytic cycle with minimal alkene isomerization, desired cyclizations proceed in preference to alternative pathways, even under relatively high substrate concentration.     

异长叶烯Prins反应及其产物的分离

探讨了异长叶烯的Prins反应条件及其产物的分离．异长叶烯的Prins反应产物主要有两种,这两种化合物很难分离,该文用柱层析成功地把这两种化合物分离出来,纯度可达97．2％．     

钌催化1,6-烯炔环化反应的研究进展

五元环和六元环是许多药物及生物活性分子中的基本结构单元,广泛存在于各种天然产物中.因此,开发高效的合成方法构筑五元/六元环一直是有机合成的热点课题之一.其中,由于过渡金属钌(Ru)催化1,6-烯炔的环化反应具备原子经济、反应条件温和、对官能团兼容性好、产率和选择性高等特点,近年来得到了研究者的广泛青睐.基于反应机理及产物的多样性,简要综述了Ru催化1,6-烯炔环化反应的发展历程和最新进展.     

Enantioselective halocyclization of polyprenoids induced by nucleophilic phosphoramidites

Polycyclic bio-active natural products that contain halogen atoms have been isolated from a number of different marine organisms. The biosynthesis of these natural products appears to be initiated by an electrophilic halogenation reaction at a carbon-carbon double bond via a mechanism that is similar to a proton-induced olefin polycyclization. Enzymes such as haloperoxidases generate an electrophilic halonium ion (or its equivalent), which reacts with the terminal carbon-carbon double bond of the polyprenoid, enantioselectively inducing a cyclization reaction that produces a halogenated polycyclic terpenoid. Use of an enantioselective halocyclization reaction is one possible way to chemically synthesize these halogenated cyclic terpenoids; although several brominated cyclic terpenoids have been synthesized via a diastereoselective halocyclization reaction that uses stoichiometric quantities of a brominating reagent, the enantioselective halocyclization of isoprenoids induced by a chiral promoter has not yet been reported. Here we report the enantioselective halocyclization of simple polyprenoids using a nucleophilic promoter. Achiral nucleophilic phosphorus compounds are able to promote the diastereoselective halocyclization reaction to give a halogenated cyclic product in excellent yields. Moreover, chiral phosphoramidites promote the enantioselective halocyclization of simple polyprenoids with N-iodosuccinimide to give iodinated cyclic products in up to 99% enantiomeric excess and diastereomeric excess. To the best of our knowledge, this is the first successful example of the enantioselective halopolycyclization of polyprenoids.     

3-二氢吡咯烷基螺环氧化吲哚及其衍生物的合成与表征

对3-二氢吡咯烷基螺环氧化吲哚及其衍生物进行了探索合成。在有机小分子碱三乙胺催化作用下,由N-2,2,2-三氟乙基靛红酮亚胺与丁炔二酸二甲酯在二氯甲烷(DCM)溶剂中于室温下发生3+2环合加成反应,高产率(83%~98%)获得3-二氢吡咯烷基螺环氧化吲哚。这一合成方法具有简单,高效,环保的特点。通过核磁共振氢谱和碳谱、高分辨质谱等手段对已合成的产物进行表征。     

Biomimetic synthesis and optimization of cyclic peptide antibiotics

Molecules in nature are often brought to a bioactive conformation by ring formation (macrocyclization). A recurrent theme in the enzymatic synthesis of macrocyclic compounds by non-ribosomal and polyketide synthetases is the tethering of activated linear intermediates through thioester linkages to carrier proteins, in a natural analogy to solid-phase synthesis. A terminal thioesterase domain of the synthetase catalyses release from the tether and cyclization. Here we show that an isolated thioesterase can catalyse the cyclization of linear peptides immobilized on a solid-phase support modified with a biomimetic linker, offering the possibility of merging natural-product biosynthesis with combinatorial solid-phase chemistry. Starting from the cyclic decapeptide antibiotic tyrocidine A, this chemoenzymatic approach allows us to diversify the linear peptide both to probe the enzymology of the macrocyclizing enzyme, TycC thioesterase, and to create a library of cyclic peptide antibiotic products. We have used this method to reveal natural-product analogues of potential therapeutic utility; these compounds have an increased preference for bacterial over eukaryotic membranes and an improved spectrum of activity against some common bacterial pathogens.     

吡啶N-衍生物直接烃基化反应的研究进展

吡啶结构单元广泛地存在于天然产物、药物和功能材料中。近年来,通过C—H键的活化,高效、高选择性地对吡啶N衍生物进行直接烃基化已成为吡啶化学中构建吡啶化合物非常重要的合成方法。本文总结了近年来吡啶N_衍生物直接烃基化反应的最新进展,同时列举了这些方法在天然产物和药物合成中的应用实例。     

咪唑啉缓蚀剂合成过程中成环程度与其性能的关系

以油酸、二乙烯三胺为原料在160 ℃经不同反应时间合成了系列咪唑啉,应用红外光谱、紫外分光光度法对合成产物进行了鉴定和分析,测定了不同反应时间的产水率和产物的酸值,并通过极化曲线考察了产物的缓蚀性能.结果表明:咪唑啉合成过程中,烷基酰胺的生成和烷基酰胺的环化是同时进行的;反应时间越长,烷基酰胺环化程度越高,产物的缓蚀性能越好;通过比较添加缓蚀剂前后A3钢的极化曲线可以看出,添加缓蚀剂后自腐蚀电位正移,说明咪唑啉主要抑制阳极过程而起到缓蚀作用,属于阳极型缓蚀剂.     

铜催化N-芳基丙烯酰胺与丙酮成环合成吲哚酮

发展了一种高效、简单的铜催化活泼烯烃羰基化成环合成吲哚酮的方法.以氯化亚铜为催化剂,二叔丁基过氧化物（DTBP）为氧化剂,丙酮为溶剂兼反应物,在100 ℃条件下与N-芳基丙烯酰胺类化合物发生自由基串联环化反应,高效地合成了一系列吲哚酮衍生物.探索不同温度、催化剂、溶剂等因素对反应的影响,并推导此环化反应的机理过程.