无溶剂体系酶促阿魏酸双甘酯合成的研究

对酶催化合成阿魏酸双甘酯的脂肪酶进了筛选和比较,并对影响合成阿魏酸双甘酯的因素(助溶剂、转速、底物比、时间、温度、水含量和硅藻土添加量)进行了探讨,结果表明无溶剂反应体系中阿魏酸双甘酯的产率远远高于含有助溶剂体系中反应.同时优化了反应条:无溶剂体系中在70mg CRL催化下,转速为150 r/m in,底物比为1:1,反应时间为120 h,水含量为10 ug/g,硅藻土添加量为40 mg时产率可达33.25%.     

糠偶姻单酯类化合物的合成

以糠醛为基础原料,经维生素B1催化合成糠偶姻,再由糠偶姻分别和乙酰氯、月桂酰氯、苯甲酰氯、α-呋喃甲酰氯和3-α-呋喃烯丙酰氯反应,在NaOH/无水THF体系中,于水浴回流条件下合成了相对应的糠偶姻单酯类化合物。醋酸糠偶姻酯(1)、月桂酸糠偶姻酯(2)、苯甲酸糠偶姻酯(3)、α-呋喃甲酸糠偶姻酯(4)和3-α-呋喃丙烯酸糠偶姻酯(5)的收率以糠偶姻计算,分别为99.3%、96.5%、98.0%、99.4%和98.7%。并通过元素分析、Mass谱、1HNMR谱对所合成的目标产物(1、2、3、4和5)分别进行了表征。     

可透皮吸收的白藜芦醇月桂酸单酯的合成与纯化

以白藜芦醇(Res)、月桂酰氯(LC)为原料,在催化剂4-二甲氨基吡啶(DMAP)的作用下,合成白藜芦醇月桂酸酯。实验结果指出:白藜芦醇与月桂酰氯摩尔比为0.8、催化剂为白藜芦醇质量的5%、pH值为11、反应时间为4 h为合成白藜芦醇月桂酸酯的最佳工艺。因素Res/LC摩尔比对白藜芦醇的转化率影响极显著,催化剂添加量和反应体系pH值为较显著。以半制备高效液相色谱分离纯化白藜芦醇月桂酸单酯的条件为:C18柱;检测波长:306nm;柱温:25℃;进样量:18mL;流速:18mL·min~(-1);时间程序:0～30min,甲醇/水(mL·mL~(-1))由50∶50梯度变化至70∶30,30～45min,甲醇与水体积比恒定为70∶30;将半制备分离物进行无水甲醇重结晶,纯度达99.3%。LC-MS、~1H NMR分析表明:该合成物为白藜芦醇月桂酸单酯。透皮实验结果指出:白藜芦醇月桂酸单酯在0.5 h内可全部透过皮肤。     

3,4-二羟基-2,5-双-[2-′(4′-取代唑啉)]呋喃的合成及其应用

以3,4-二羟基-2,5-呋喃二甲酸或其二甲酯为原料,与手性氨基醇直接缩合,经一步反应合成了3个3,4-二羟基-2,5-双-[2-′(4-′-取代唑啉)]呋喃化合物,产率为90%~94%,其结构经1H NMR谱、IR谱、MS谱和元素分析测试技术得到确证;并应用这些手性双唑啉配体,初步探讨了β-萘乙酮在KBH4或NaBH4作用下的不对称还原反应。结果表明,以环己烷作溶剂,采用n(配体)∶n(还原剂)∶n(β-萘乙酮)=0.04∶1.6∶1在0℃下反应72 h,产物的ee值高达83.2%,且唑啉环上4位取代基为苄基的呋喃类双唑啉,其对映选择性优于取代基为乙基的同类配体。     

2-取代-4,5-双(α-呋喃基)噁唑的合成及发光性能的研究

以糠醛为原料, 经维生素B1 (VB1)催化合成糠偶姻. 糠偶姻与不同的酰氯反应生成糠偶姻单酯. 糠偶姻单酯在醋酸铵和醋酸作用下合成了新化合物2-取代-4,5-双(α-呋喃基)噁唑. 采用 IR, 1H NMR, MS和元素分析对目标产物进行鉴定和表征, 证实了其分子结构. 并对2-取代-4,5-双(α-呋喃基)噁唑进行了UV和荧光光谱测定, 对其进行了简单的发光性能的研究.     

高效液相色谱-蒸发光散射检测法测定合成产物中的果糖棕榈酸酯

建立了反相高效液相色谱-蒸发光散射检测（HPLC-ELSD）测定合成产物中的果糖棕榈酸单酯和果糖棕榈酸双酯的方法。HPLC-ELSD条件为：反相Prevail C18色谱柱,柱温为30 ℃,流动相为乙酸乙酯-甲醇-水（体积比为59.4∶30∶10.6）,流速为1 mL/min,ELSD漂移管温度为73.8 ℃,载气流速为2 L/min。在该色谱条件下,果糖棕榈酸单酯及果糖棕榈酸双酯在进样量为1～15 μg时,与其峰面积的线性关系良好,相关系数r2均大于0.9996。     

失水山梨醇单月桂酸酯的一步法合成

失水山梨醇单月桂酸酯(商品名Span20)用途广泛[1 4]。传统方法[5]生产出的产品色泽深、副产物多、单酯质量分数低、熔融状态下多呈浑浊状态、质量不稳定,仅能用于石油、采矿和纤维等行业,用于食品、医药、化妆品的这类产品绝大部分依赖进口。本文以山梨醇和月桂酸为原料,采用一步法合成的目标产物为乳白色,单酯质量分数大于90%。并对合成方法进行了对比,探讨了各主要影响因素对目标产物色泽和三项指标(酸值、羟值、皂化值)的影响。梨醇的醚化和酯化反应产物是一个复杂的混合物:不仅有单酯及其异构体,还会存在其它二酯、多酯及相应异构…     

氯化硅胶催化下无溶剂合成香豆素类化合物

以氯化硅胶为催化剂,应用β-酮酸酯对各种酚进行Pechmann反应,在80℃和无溶剂的条件下,合成了一系列香豆素类化合物.该方法具有反应条件温和,产率高(67%～96%)和操作简单等优点.产物结构经IR,1H NMR,元素分析等进行了表征.     

铜催化炔丙醇酯与β-羰基膦酸酯的不对称[3+2]环加成反应合成手性膦酰化2,3-二氢呋喃

手性2,3-二氢呋喃衍生物是一类重要的杂环化合物,广泛存在于天然产物和生物活性分子中.它们也经常被用于手性四氢呋喃化合物的不对称合成.因此,人们发展了很多合成手性2,3-二氢呋喃化合物的方法,如有机小分子催化的多米诺迈克尔-烷基化反应、“中断的”Feist-Bénary反应或改进的 Feist-Bénary反应.此外,过渡金属催化的手性2,3-二氢呋喃的不对称合成在近些年引起了人们的极大关注. Ozawa等通过 Pd-催化2,3-二氢呋喃的动力拆分方法获得了手性2-芳基-2,3-二氢呋喃. Evans发展了一种 Sc-催化联烯硅和乙醛酸乙酯的[3+2]环加成反应合成手性2,3-二氢呋喃的方法.最近, Fu和 Tang等发展了 Cu催化烯酮和重氮化合物的[4+1]环加成反应合成手性2,3-二氢呋喃的方法.在 Nishibayashi和 van Maarseveen的开创性工作之后, Cu催化的不对称炔丙基转化反应取得了很大的进展.最近,我们发展了一类新的三齿手性 P,N,N-配体,在 Cu催化不对称炔丙基取代、脱羧炔丙基取代、[3+2]、[3+3]和[4+2]环加成反应中表现出优秀的对映和非对映选择性.其中,我们发现采用 Cu催化炔丙醇酯和β-酮酯的[3+2]环加成反应,能高对映选择性地获得手性2,3-二氢呋喃.我们设想,采用β-羰基膦酸酯代替β-酮酯,通过这种 Cu催化[3+2]环加成反应,将可以合成一类具有重要生物活性的手性膦酰化2,3-二氢呋喃化合物.基于这种设想,本文使用手性 P,N,N-配体,通过 Cu催化炔丙醇酯与β-羰基膦酸酯的不对称[3+2]环加成反应,以很好的收率和最高92% ee的对映选择性获得了一系列光学活性的膦酰化2,3-二氢呋喃化合物.我们以炔丙醇酯1a与β-羰基膦酸酯2a为标准底物,优化了反应条件,考察了配体、Cu盐、碱和反应温度等对反应收率和对映选择性的影响.我们确定了最佳的反应条件：以4b为配体,以 Cu(OTf)2为铜盐,以t-BuOK为碱,以 MeOH为溶剂,–20oC反应24 h.在此条件下,我们对β-羰基磷酸酯2的适用范围进行了考察.结果表明,各种苯基取代的β-羰膦磷酸酯均能得到很好的收率和对映选择性.苯环上取代基的空间效应对反应的对映选择性影响不大,但对反应收率影响较大,与相应3-取代或4-取代底物相比较,2-取代的底物获得的收率较低.苯环对位取代基的电子效应对反应的影响不大,给电子基或吸电子基的底物,均得到了较好的收率和对映选择性.杂环取代的底物同样适用于该反应,以90%的收率和89% ee的对映选择性获得了相应的[3+2]环加成产物.对于烷基底物,虽然反应的产率略低,但是得到了高达92% ee的产物.此外,我们对炔丙醇酯底物的适用范围也进行了考察.结果表明,该体系对于各种取代的炔丙醇酯底物均可以获得较高的收率和良好的对映选择性.总之,本文发展了一种铜催化炔丙醇酯与β-羰基膦酸酯的不对称[3+2]环加成反应的方法,成功合成了手性膦酰化2,3-二氢呋喃化合物.通过使用一个结构刚性的酮亚胺三齿 P,N,N-配体,以很好的收率和最高92% ee的对映选择性获得了一系列光学活性的膦酰化2,3-二氢呋喃化合物.     

以芳樟醇为手性源的β-羟基酸的不对称合成

以芳樟醇与乙酰乙酸乙酯进行酯交换反应,合成了具有手性的乙酰乙酸芳樟酯(β-酮酯),再用其与不同的格氏试剂反应,得到不对称β-羟基酸;产物分别经手性柱分析.结果表明,手性乙酰乙酸芳樟酯与格氏试剂的反应具有不同程度的立体选择性,产物为R-或S-构型过量的β-羟基酸,ee值最高达50%.     

α-Amino acid derived enaminones and their application in the synthesis of N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates and other heterocycles

A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives.     

Specific intramolecular aromatic CH insertion of diazosulfonamides

The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp³)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp²)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp²)?H and aliphatic 1,5- and 1,6-C(sp³)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp³)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp²)?H insertion.     

N-Heterocyclic carbene-palladacyclic complexes: synthesis,characterization and their applications in the C-N coupling and α-arylation of ketones using aryl chlorides

N-Heterocyclic carbene-palladacyclic complexes 3 were successfully achieved in a one-pot procedure under mild conditions. The structure of 3a was unambiguously confirmed by X-ray single crystal diffraction and it was an active catalyst in the Buchwald-Hartwig amination and α-arylation of ketones even at very low catalyst loadings (0.01?mol%).     

Iodine-mediated oxidative Pictet-Spengler reaction using terminal alkyne as the 2-oxoaldehyde surrogate for the synthesis of 1-aroyl-β-carbolines and fused-nitrogen heterocycles

An efficient iodine-mediated oxidative Pictet-Spengler reaction in dimethyl sulphoxide (DMSO) using terminal alkynes as the 2-oxoaldehyde surrogate for the synthesis of aryl (9H-pyrido[3,4-b]indol-1-yl)methanones is described. The scope of the protocol includes the total synthesis of Fascaplysin, Eudistomins Y₁ and Y₂. The methodology is extended for preparing pyrrolo[1,2-a]-quinoxaline and indolo[1,5-a]quinoxaline derivatives. The utility of 1-aroyl-β-carbolines was demonstrated by performing palladium-catalyzed β-carboline directed ortho-C(sp2)-H functionalization of the phenyl ring with thiomethyl (SMe) group using DMSO as source and for accessing 4-aryl-canthin-6-ones.     

Facile synthesis of bicyclic 1-arylpyrazol-5-ones

In this Letter, we described a facile method for constructing fused bicyclic 1-arylpyrazol-5-one ring system. We employed various methylene-containing carboxylic acids as the substrates and proved that the pyrazolone ring closure requires activated methylene group in intermediate II. Accordingly, a series of structurally diversified, fused bicyclic 1-arylpyrazol-5-ones was prepared in moderate to high yields using the requisite substrates.     

A carbanion induced synthesis of highly congested pyrazole and imidazole containing heterocycles

An efficient approach to the synthesis of highly congested di, penta and hexacyclic pyrazoles as well as imidazole fragment containing novel heterocyclic molecule has been developed through a carbanion induced transformation of suitably functionalized 2H-pyran-2-ones, benzo[h]chromene and thiochromeno[4,3-b]pyrans. Due to the presence of fluorescence, we report their prime application metal sensor as off/on switching in ferric ions.     

Synthesis of pyrrolo[1,2-a]pyrazines and pyrazino[1,2-a]indoles by Curtius reaction in Morita-Baylis-Hillman derivatives

Synthesis of substituted pyrrolo[1,2-a]pyrazines and pyrazino[1,2-a]indoles from the Morita-Baylis-Hillman derivatives of acrylates via saponification followed by Curtius reaction is described.     

正丁胺对激光染料荧光谱影响的研究

用正丁胺作为碳源,采用射频辉光放电制备碳膜,选用激光染料R6G和聚乙二醇混合液作为蒸气源,采用单源热蒸发,在蒸发室与染料同时沉积得到混合膜,用拉曼光谱和红外光谱分析了碳膜的结构和键合方式,分析表明:碳膜中存在胺基团和氢原子.混合膜的荧光谱测量结果表明,认为正丁胺对染料荧光谱的影响是因为胺基和氢原子的存在.     

Selective synthesis of 4,5-dihydroimidazo- and imidazo[1,5-a]quinoxalines via modified Pictet–Spengler reaction

An efficient tandem approach for the selective synthesis of 4,5-dihydroimidazo[1,5-a]quinoxalines 6a–g and imidazo[1,5-a]quinoxalines 7a–h by the reaction of 2-imidazolyl anilines 4a–c with aryl aldehydes 5a–k under mild reaction conditions is described. Introduction of electron releasing alkyl groups in substrates 4a–b was found to be instrumental for the success of the reaction.     

Understanding the Diels-Alder reactivity of 1,2-azaborine analogues

The Diels-Alder reactivity of 1,2-heteroborines (H₄C₄B(H)X, X?=?NH, PH, AsH; O, S, Se) has been computationally explored by means of Density Functional Theory (DFT) calculations. The influence of the HB?=?X fragment on the reactivity of the system has been quantitatively analyzed in detail by means of the so-called Activation Strain Model (ASM) of reactivity. It is found that the interaction between these species and the dienophile is significantly stronger than that computed for their all-carbon isoelectronic counterpart, benzene. In addition, the strain energy plays a key role in the observed reactivity trends. The role of the aromaticity strength of these heteroarenes on the reactivity is also assessed.