An Alternative Method for Anomeric Deacetylation of Per-acetylated Carbohydrates

An alternative method for anomeric deacetylation of fully acetylated carbohydrates has been developed using imidazole in methanol.     

Synthesis of Thioglycosides with Nitrogen-Containing Heterocyclic Fragments

A number of thioglycosides derived from benzoylated glucopyranose and nitrogen-containing heterocyclic thiols have been synthesized in up to 98% yield, and benzoyl protecting groups have been removed from the glycoside with a 3-phenyl-4-oxo-3,4-dihydroquinazolin-2-ylsulfanyl fragment.     

Microwave Irradiation for Accelerating the Synthesis of Thioglycosides

A simple and efficient procedure for the synthesis of thioglycosides has been achieved from the reaction of glycosylisothiouronium salts with alkyl or heteroaryl halides under microwave irradiation, in much shorter times and in yields comparable with conventional methods.     

全偶氮苯官能化树枝状聚合物的合成

以4-羧基-4'-(1, 2-丙二醇醚)-偶氮苯为AB2单体, 由4-羧基-4'-正丁基醚-偶氮苯出发, 采用收敛法合成了以偶氮苯为结构单元的新型树枝状聚合物, NMR, GPC和 MALDI-TOF-MS的测试结果表明, 合成的树枝状分子具有规整的分子结构和单分散的分子量分布.     

Synthesis and Selected Reactions of Hydrazides Containing an Imidazole Moiety

The preparation of two types of imidazole derivatives bearing a hydrazide group was achieved by treatment of the corresponding esters with NH₂NH₂?H₂O in MeOH at room temperature. In the case of 4‐(ethoxycarbonyl)‐1H‐imidazole 3‐oxides 3 , hydrazides of type 1 were formed with retention of the N‐oxide structure (Scheme 1). Interestingly, due to a strong H‐bonding, no deoxygenation of the N→O function could be achieved even by treatment of 3 with Raney‐Ni. The second type, 2‐[(1H‐imidazol‐2‐yl)sulfanyl]acetohydrazides 2 , was obtained from 1H‐imidazole‐2(3H)‐thiones 4 in two steps via S‐alkylation with methyl bromoacetate, followed by treatment with NH₂NH₂?H₂O (Scheme 2). An imidazole 7 , containing both types of hydrazide groups, was prepared analogously from ethyl 2,3‐dihydro‐2‐thioxo‐1H‐imidazole‐4‐carboxylate 4d (Scheme 4). Both types of hydrazides, 1 and 2 , were transformed successfully to the corresponding acylhydrazones 8 and 9 , respectively (Scheme 5). Furthermore, it has been shown that hydrazides of type 1 are useful starting materials for the synthesis of 1,2,4‐triazole‐3‐thiones 11 and 1,3,4‐thiadiazole‐2‐amines 12 , bearing an imidazole 3‐oxide moiety (Scheme 7).     

含有螺环己烷结构的稠环斯德酮的合成

3-(3-芳基-3-羟基丙基)斯德酮在三氟化硼乙醚的催化作用下可以与环己酮发生类似于Oxa-Pictet-Spengler反应的成环反应,生成带有螺环己烷结构的稠环斯德酮.     

Synthesis and Photocytotoxicity of Mono-functionalised Porphyrin with Valine Moiety

A mono-funtionalised tetraphenylporphyrin (TPP) bearing valine moiety at the phenyl ring was synthesized for photocytotoxicity examination in four steps, starting from regiospecific mono-nitration of TPP at the phenyl ring. The in vitro photocytotoxicitic effect against SPC-Al adenocarcinona cell line was tested.     

A Facile and Efficient Method for the One-Pot Synthesis of Per-O-acetylated Thioglycosides from Unprotected Sugars

An efficient, convenient protocol for the preparation of per-O-acetylated p-tolylthio glycosides is described. Treatment of various unprotected sugars, including 2-deoxy-2-amino sugars, sialic acid, lactose, and maltose, with acetic anhydride using SnCl₄ as a catalyst, and subsequently with p-tolylthiol, furnished the corresponding thioglycosides in 71%–90% yield under solvent-free conditions.     

新型含1,2,3-三氮唑的染料木素糖缀合物的合成

以染料木素为起始原料,经两步反应制得中间体7-O-炔丙基染料木素(3);以CuI为催化剂,3与叠氮乙酰基糖经Click反应合成了7-O-［1-(2,3,4,6-四-O-乙酰基-β-D-糖苷)1H-1,2,3-三氮唑-4-甲基］-染料木素(5a~5c); 5a~5c经去乙酰基制得三种含1,2,3-三氮唑的氮苷染料木素糖缀合物(6a~6c)。3, 5和6均为新化合物,其结构经¹H NMR, ¹³C NMR和HR-MS表征。     

一锅法合成甲基丙烯酰基封端的PLA-PEG-PLA大分子单体

以辛酸亚锡[Sn(Oct)2]为催化剂、聚乙二醇为引发剂引发丙交酯开环聚合,用水终止反应后再加入甲基丙烯酸酐反应即可得到甲基丙烯酰基封端的PLA-PEG-PLA大分子单体。上述两步反应可一锅进行,操作简便、收率高。采用GPC、FTIR、^1H-NMR、TG、XRD等分析手段表征了大分子单体的结构和性质。所得大分子单体的水溶液在光引发剂存在下,能被UV引发光聚合形成水凝胶。该水凝胶作为可降解生物材料可用于药物控释栽体和组织工程支架。     

新型含磷双酚A型共聚碳酸酯的合成与表征

新型含磷双酚A型共聚碳酸酯的合成与表征;聚碳酸酯;三光气;合成;阻燃     

含取代噁唑结构的新型吡唑肟衍生物的合成与生物活性

为了发现具有良好生物活性的吡唑肟化合物,以唑螨酯为先导化合物,在吡唑肟中引入取代噁唑结构,设计并制备了20个未见文献报道的新型吡唑肟衍生物,利用1H NMR,13C NMR和元素分析确证了目标产物的结构.生物活性测试结果显示,部分目标化合物在500和100μg/mL浓度下对粘虫或蚜虫表现出优良的杀虫活性,其中5-(3-氟苯氧基)-1,3-二甲基-1H-吡唑-4-甲酰基-O-{[5-(4-氯苯基)噁唑-2-基]甲基}肟(9j)、5-(4-氟苯氧基)-1,3-二甲基-1H-吡唑-4-甲酰基-O-{[5-(4-氯苯基)噁唑-2-基]甲基}肟(9k)、5-(4-叔丁基苯氧基)-1,3-二甲基-1H-吡唑-4-甲酰基-O-{[5-(4-氯苯基)噁唑-2-基]甲基}肟(9r)和5-(4-甲氧基苯氧基)-1,3-二甲基-1H-吡唑-4-甲酰基-O-{[5-(4-氯苯基)噁唑-2-基]甲基}肟(9s)在浓度为100μg/mL时对粘虫的防治效果均达100%,5-(4-溴苯氧基)-1,3-二甲基-1H-吡唑-4-甲酰基-O-{[5-(4-氟苯基)噁唑-2-基]甲基}肟(9g)和9s在浓度为100μg/mL时对蚜虫的杀灭活性均为100%.此外,化合物9s在500μg/mL时对朱砂叶螨的防治效果为70%.     

The First Reaction of Dimethoxycarbene with an Imine Moiety

The nucleophilic dimethoxycarbene (DMC; 2 ) generated by thermal decomposition of 2,5‐dihydro‐1,3,4‐oxadiazole derivative 1 in boiling toluene reacts smoothly with N‐(9H‐fluoren‐9‐ylidene)‐4‐methylbenzenesulfonamide ( 7b ) to yield carbonimidoate derivative 10 . A multi‐step reaction pathway, initiated by the attack of DMC onto the C?N bond and followed by the migration of the sulfonyl group (or via a sulfinate anion) is proposed to explain the formation of the final product. In contrast to the formal ketimine 7b , N‐benzylidene‐4‐methylbenzenesulfonamide ( 7a ), a formal aldimine, does not react with DMC under comparable conditions.     

含双酚芴聚碳酸酯的合成与光学性能

将具有负双折射系数的双酚芴{9,9-二[4-(2-羟乙氧基)苯基]芴, BPEF}与双酚A(BPA)共聚, 制备本征双折射率接近零的含双酚芴聚碳酸酯(共聚PC). 研究发现, 碱性强、 pK_a值大的催化剂可以缩小BPA和BPEF的活性差异, 有利于制备高分子量含双酚芴聚碳酸酯, 缩聚温度为265 ℃、 缩聚时间为40 min时产物具有较高的分子量和较低的黄变指数. BPEF和BPA投料比(摩尔比)为40/60时共聚体系的重均分子量可达39800, ¹H NMR和¹³C NMR测试证明分子链呈无规共聚结构. 随着BPEF含量的上升, 共聚PC的折射率从1.586提高到1.639, 本征双折射率从0.1948下降到-0.0102. 当BPEF摩尔分数为87%时, 共聚PC的本征双折射率低至0.0028, 非常接近零双折射.     

Efficient Microwave-Assisted Synthesis of Some N-Heterocycles Integrated with a Pyrazole Moiety

Russian Journal of Organic Chemistry - An efficient and rapid synthesis of new heterocyclic compounds via reactions of 1,3-diphenyl-1H-pyrazole-4-carbaldehyde thiosemicarbazone with some carbon...     

Sulfur and Azobenzenes,a Profitable Liaison: Straightforward Synthesis of Photoswitchable Thioglycosides with Tunable Properties

Azobenzene photoswitches are valuable tools for controlling properties of molecular systems with light. We have been investigating azobenzene glycoconjugates to probe carbohydrate-protein interactions and to design glycoazobenzene macrocycles with chiroptical and physicochemical properties modulated by light irradiation. To date, direct conjugation of glycosides to azobenzenes was performed by reactions providing target compounds in limited yields. We therefore sought a more effective and reliable coupling method. In this paper, we report on a straightforward thioarylation of azobenzene derivatives with glycosyl thiols as well as other thiols, thereby increasing the scope of azobenzene conjugation. Even challenging unsymmetrical conjugates can be achieved in good yields via sequential or one-pot procedures. Importantly, red-shifted azoswitches, which are addressed with visible light, were easily functionalized. Additionally, by oxidation of the sulfide bridge to the respective sulfones, both the photochromic and the thermal relaxation properties of the core azobenzene can be tuned. Utilizing this option, we realized orthogonal three-state photoswitching in mixtures containing two distinct azobenzene thioglycosides.     

Improved Synthesis of 1‐Benzenesulfinyl Piperidine and Analogs for the Activation of Thioglycosides in Conjunction with Trifluoromethanesulfonic Anhydride*

An improved protocol for the large‐scale production of 1‐benzenesulfinyl piperidine and other sulfinamides is described. It is demonstrated that 1‐benzenesulfinyl pyrrolidine and N,N‐diethyl benzenesulfinamide function analogously to 1‐benzenesulfinyl piperidine in the trifluoromethanesulfonic anhydride‐mediated activation of thioglycosides, and that their less crystalline nature enables them to be used at ?78°C as opposed to the ?60°C required to keep 1‐benzenesulfinyl piperidine in solution. N,N-Dicyclohexyl benzenesulfinamide does not activate thioglycosides in combination with trifluoromethanesulfonic anhydride, which is attributed to its greater steric bulk.     

Preparation of an Advanced Intermediate for the Synthesis of Stable Analogues of Guanofosfocin

The synthesis of C‐mannosyl‐guanosine 23 , an advanced intermediate for the preparation of stable analogues of guanofosfocin, is described. This convergent approach features an improved Traube‐type synthesis of a 8‐substituted guanine, followed by ribosylation. NMR Studies show that the C‐mannopyranosyl moiety of 23 adopts a distorted ¹C₄ conformation while the nucleoside is predominantly syn‐oriented.