双(3-氨基-4-羟基苯基)双酚醚类化合物的合成

以双酚化合物及对卤苯酚为起始原料,经用苄基保护、乌尔曼成醚、选择性硝化和还原脱保护4步反应,合成了具有双酚芳香醚结构的4个新型聚苯并噁唑单体：双(3-氨基-4-羟基苯基)双酚醚类化合物的盐酸盐。 确定了乌尔曼成醚反应的最佳工艺条件,证明硝化反应只发生在对卤苯酚苄保护基的邻位,改进了还原脱保护反应的成盐及后处理条件,提高了产物的质量和收率,4步反应总收率可达54.0%。 采用红外光谱、核磁共振H谱和高分辨质谱表征了每步产物的化学结构。     

取代8-羟基喹啉钌络合物催化Friedl?nder反应合成喹啉衍生物

Friedl?nder喹啉合成法是以邻胺基芳基醛或酮与有α-亚甲基的酮环化制备喹啉的反应,报道了一种喹啉钌络合物催化Friedl?nder法合成喹啉的方法.首先,以8-羟基喹啉钌络合物为催化剂,对模板反应邻氨基苯甲醇和苯乙酮合成2-苯基喹啉进行了反应条件优化实验.重点对比研究了8-羟基喹啉钌络合物配体上不同取代基对反应收率的影响,其中5-甲基-8-羟基喹啉(1e)钌络合物催化邻氨基苯甲醇和苯乙酮合成2-苯基喹啉获得了73%的最高收率.结合IR, UV以及密度泛函理论(DFT)计算讨论了配体结构与催化性能之间的关系.提出了β-H消除形成醛过渡态,交叉aldol反应再亚胺环化,最后脱水生成目标产物的可行机理.以(1e)₃Ru为催化剂,在优化的反应条件下进行了底物扩展研究,以69%～94%的收率合成了32个不同取代的喹啉衍生物,验证了方法的普适性.     

(S)-(-)-5-对苄氧基苄基-2,4-噁唑烷二酮的合成

L-酪氨酸经O-苄基化和重氮化反应得到关键中间体--手性3-(对苄氧基苯基)-α-羟基丙酸(4); 4经酯化、氨化和环化反应合成了(S)-(-)-5-对苄氧基苄基-2,4-噁唑烷二酮,总收率10%, 95.4%e.e.,其结构经1H NMR和HR-MS表征.     

新型多肽固相合成链接子{4-[叔丁氧羰基氨基-(2’,4’-二甲氧基苄基)]苯氧基乙酸}的合成

以4-羟基苯甲酸和间苯二甲醚为原料,经傅-克酰基化反应、苄基保护、还原氨化、Boc保护氨基、脱苄基、亲核取代反应、酯水解等7步反应合成了一个新型的多肽固相合成的链接子4-[叔丁氧羰基氨基-(2’,4’-二甲氧基苯基)]苯氧基乙酸,总收率47.2%,纯度>98%,其结构经1H NMR,13C NMR和HR-MS确证。     

FeCl3催化4-羟基香豆素烷基化衍生物的合成

以4-羟基香豆素、查尔醇（或苄醇）为原料,FeCl₃作催化剂,1,2-二氯乙烷作溶剂,在室温下实现了4-羟基香豆素的烷基化反应,高效合成了10个4-羟基香豆素的烷基化衍生物（3a~3e, 5a~5e）,收率70%~91%和67%~78%。在此基础上,利用FeCl₃/DDQ催化体系的一锅法串联环化反应合成了一系列2,4-二芳基-2H,5H-吡喃并[3,2-c]苯并吡喃-5-酮衍生物（6a~6d）,收率52%~85%。其中3b, 3d, 3e, 6b, 6c, 6d为新化合物,其结构经¹H NMR, ¹³C NMR和HR-MS（ESI）表征。     

苯基磺酸官能化分子筛催化合成香豆素类化合物

在苯基磺酸官能化介孔分子筛催化剂作用下 ,取代苯酚和乙酰乙酸乙酯经Pechmann缩合反应合成系列取代香豆素类化合物 .该催化合成反应具有条件温和、产物容易分离、收率高等优点 .考察了不同位置取代羟基对该缩合反应的影响 .结果表明 ,间位羟基有利于香豆素衍生物的生成 ,提高反应收率 ,对位羟基次之 .证实了该固体酸催化活性位为磺酸Br nsted型质子酸     

新型含双长链和苄基的有机硅季铵盐的合成

以双十二胺(1)为原料,与氯化苄经取代反应制得中间体苄基双十二胺(2);2与γ-氯丙基三甲氧基硅烷(3)经季铵化反应合成了一种新型的含双长链和苄基的有机硅季铵盐(4),其结构经UV-Vis和FT-IR表征。通过正交实验L9(34)优化了2和4的反应条件。合成2的最佳工艺条件为:以乙腈为溶剂,1 5 mmol,n(1)∶n(Bn Cl)=1.0∶1.2,回流反应20 h,收率80.4%。合成4的最佳工艺条件为:以乙二醇为溶剂,2 5mmol,n(2)∶n(3)=1.0∶1.6,于110℃密闭反应80 h,收率57.8%。     

季鏻盐/ZnCl2催化合成苄基甲苯

研究了季鏻盐/ZnCl2催化甲苯与氯化苄合成苄基甲苯的反应.较佳反应条件为:季鏻盐9.4 mmol,n(季鏻盐)∶n(氯化苄)=1∶40,于100℃反应5h.在最佳反应条件下,氯化苄转化率近100％,单双苄基甲苯总收率95％.季鏻盐/ZnCl2催化剂可循环使用24次以上.     

季铵盐催化氧化法合成硝基苯甲酸

研究了季铵盐A－1催化KMnO4分别氧化邻、对硝基甲苯合成邻、对硝基苯甲酸的反应。考察了不同相转移催化剂的催化活性及催化剂用量、反应温度、反应时间、KMnO4用量和反应体系酸碱性对反应的影响。在优化反应条件下，即以季铵盐A－1为相转移催化剂，KMnO4与硝基甲苯摩尔比为2．5：1，反应温度为95℃，反应时间为3h，在中性条件下进行反应，邻位、对位产物收率分别可达95%和92%。实验表明，季铵盐A－1对于KMnO4氧化硝基甲苯合成硝基苯甲酸的反应是一种优良的相转移催化剂。     

溴化四丁铵催化苯乙烯一步合成苯乙烯环状碳酸酯

以溴化季铵盐为催化剂, 通过苯乙烯的环氧化和CO2的加成反应一步直接合成出苯乙烯环状碳酸酯, 详细考察了催化剂的用量、氧化剂的种类、反应温度、反应时间和CO2压力等因素对反应主产物收率的影响. 结果表明, 以溴化四丁铵为催化剂, 于80 ℃和1 MPa CO2下反应6 h, 环状碳酸酯的收率达到38%, 这是季铵盐阳离子和亲核性阴离子协同催化的结果.     

Polymer-supported Cinchona alkaloid-derived ammonium salts as recoverable phase-transfer catalysts for the asymmetric synthesis of alpha-amino acids

Alkaloids such as cinchonidine, quinine and N-methylephedrine have been N-alkylated using polymeric benzyl halides or co-polymerized and then N-alkylated, thus affording a series of polymer-supported chiral ammonium salts which have been employed as phase-transfer catalysts in the asymmetric benzylation of an N-(diphenylmethylene)glycine ester. These new polymeric catalysts can be easily recovered by simple filtration after the reaction and reused. The best ee's were achieved when Merrifield resin-anchored cinchonidinium ammonium salts were employed.     

Cumyl ester as the C-terminal protecting group in the enantioselective alkylation of glycine benzophenone imine

Cumyl ester is an optimal C-terminal protecting group for glycine benzophenone imine in asymmetric alkylation reactions catalyzed by Cinchona chiral phase-transfer catalysts. High levels of enantioselectivity have been obtained (up to 94% ee) with this substrate, which provides an attractive alternative to the analogous tert-butyl ester. N-terminal imines and the C-terminal esters can be cleaved from alkylation products by hydrogenolysis, while maintaining acid-labile side chain protecting groups.     

Evidence of the electronic factor for the highly enantioselective catalytic efficiency of Cinchona-derived phase-transfer catalysts

[structure: see text] The Cinchona alkaloid-derived quaternary ammonium salts containing 2'-N-oxypyridine and 2'-cyanobenzene moieties were prepared and evaluated as phase-transfer catalysts in the enantioselective alkylation of glycine imine ester 1. The N-oxypyridine and cyanobenzene moieties might play an important role to form a rigid conformation by coordinating with H(2)O via hydrogen bonding leading to high enantioselectivity (97 approximately >99% ee), which provides evidence of an electronic factor for the high enantioselective catalytic efficiency in phase-transfer alkylation.     

An unusual electronic effect of an aromatic-F in phase-transfer catalysts derived from cinchona-alkaloid

[structure: see text] Various N-benzylcinchonidinium salts were prepared to study electronic factors in the catalytic enantioselective phase-transfer alkylation of glycine anion equivalent. An ortho-fluoro substituent on the benzyl group in the quaternary ammonium salt dramatically increased the enantioselectivity in the alkylation. O(9)-Allyl-N-2',3',4'-trifluorobenzylhydrocinchonidinium bromide (27), which gave the highest enantioselectivity of the catalysts studied, was used to prepare 12 alpha-alkylated amino acid derivatives in 94 approximately >99% ee.     

季鏻盐型三相相转移催化剂的制备及其化学结构与相转移催化活性的关系

 使用两种 ω-氯代酰氯 (氯乙酰氯与氯丁酰氯) 对交联聚苯乙烯微球 (CPS) 进行 Friedel-Crafts 酰基化反应,使用 1,4-二氯甲氧基丁烷对 CPS 微球进行氯甲基化反应, 分别将可交换的氯引入 CPS 微球表面, 制备了化学改性的 CPS 微球. 然后使用三苯基膦对改性微球进行季鏻化反应, 制备了间隔臂 (spacer arm) 长度不同的三种季鏻 (QP) 盐型三相相转移催化剂 QP-CPS. 考察了主要反应条件对制备过程的影响, 并以氯化苄与乙酸钠合成乙酸苄酯的反应体系作为三相相转移催化的模型体系, 初步考察了 QP-CPS 的相转移催化活性,探索了催化剂结构与相转移催化活性的关系. 结果表明, 季鏻盐的化学稳定性较差,在制备过程中需控制反应时间与温度, 且宜选用极性较高的溶剂. 季鏻盐型三相相转移催化剂 QP-CPS 对乙酸苄酯的合成具有较高的催化活性, 在液-固-液之间可有效地实现反应物种乙酸根的转移. 与季铵盐 (QN) 型三相相转移催化剂 QN-CPS 相比, 季鏻盐型三相相转移催化剂 QP-CPS 具有更高的相转移催化活性. 间隔臂越长, QP-CPS 的相转移催化活性越高, QP-CPS 的亲水和亲油性能对相转移催化活性也有很大的影响.     

季铵盐中N-手性在不对称烷基化反应中的作用研究

为了探明手性季铵盐中N-手性在不对称烷基化反应中的作用,从天然氨基酸出发合成了4个仅含C-手性的季铵盐.将它们与4个同时含有C-和N-手性的季铵盐用于催化二苯亚胺甘氨酸叔丁酯的不对称烷基化反应,通过对烷基化产物的ee值进行比较,结果表明简单的链状季铵盐中的N-手性不能对烷基化产物的ee值产生明显影响.     

New polymer-supported chiral phase-transfer catalysts in the asymmetric synthesis of α-amino acids: the role of a spacer

Polymer-supported cinchona alkaloid salts with different spacers were used as phase-transfer catalysts in the asymmetric C-alkylation of N-diphenyl methylene glycine tert-butyl ester. Various catalysts and alkylation conditions were studied, the best result being 81% e.e. with cinchoninium iodide bound to polystyrene with a four-carbon spacer.     

Phase-Transfer Reactions Catalyzed by Polymer-Supported Imidazoles

Abstract

Polymer-supported imidazoles were prepared by copolymerization of vinyl monomers containing imidazole moiety, styrene, and divinylbenzene with AIBN. The resulting polymers accelerated the reaction of octyl bromide with potassium thiocyanate, and the alkylation of an active methylene compound, benzyl cyanide, under phase-transfer conditions. The latter catalytic reaction afforded monoalkylated compound exclusively, although dialkylated compound was also obtained in monomeric alkylimidazole catalyzed reaction. Further, these polymers served as phase-transfer catalysts for the reduction of acetophenone by sodium borohydride. The relationship between the structure and catalytic activity, and the factors governing these catalytic reactions were examined.     

Synthesis and catalytic activity of a new class of cyclophosphazenic polypodands

A new class of solid-liquid phase-transfer catalysts (SL-PTC) has been prepared by the reaction of octachlo-rocyclotetraphosphazatetraene and polyethylene glycol monoalkyl ether. These polypodands are found to be powerful metal cation complexing agents and very efficient catalysts in anion promoted reactions (e.g. nucleophilic substitution and reduction reactions).     

Phase-transfer-catalyzed asymmetric acylimidazole alkylation

2-Acylimidazoles are alkylated under phase-transfer conditions with cinchonidinium catalysts at -40 degrees C with allyl and benzyl electrophiles in high yield with excellent enantioselectivity (79 to >99% ee). The acylimidazole substrates are made in three steps from bromoacetic acid via the N-acylmorpholine adduct. The catalyst is made in high purity allowing for S-product formation (6-20 h) under mild conditions, consistent with an ion-pair mechanism. The products are readily converted to useful ester products using methyltriflate and sodium methoxide, via a dimethylacylimidazolium intermediate without racemization. The process is efficient, direct, and amenable to other electrophiles and transformations that proceed through an enolate intermediate.