Efficient and green tetrahydropyranylation and deprotection of alcohols and phenols by using activated carbon supported sulfuric acid

A simple, green and efficient method for the DHP protection of various alcohols and phenols and the subsequent removal of the corresponding protective group in the presence of a catalytic amount of the activated carbon supported H2SO4 is described.

Regioselective Deprotection of 1,3-Dibenzyl-5-(N,N-dimethylamino)-6-phenylethyluracil

The deprotection of 1,3-dibenzyl-5-（N,N-dimethylamino）-6-phenyl-ethyluracil I was investigated. A practical, regioselective N3 deprotection of compound I was performed with excellent yield using cyclohexene as a hydrogen donor.

Efficient oxidative deprotection of trimethylsilyl,tetrahydropyranyl and methoxymethyl ethers under solvent-free conditions

A mild, efficient and fast method for direct oxidation of trimethylsilyl, tetrahydropyranyl and methoxymethyl ethers to their corresponding carbonyl compounds using trinitratocerium（Ⅳ） bromate （TNCB） supported on NaHSO4.H2O under solvent-free conditions is reported.

Deprotection of t-Butyldimethylsiloxy (TBDMS) Protecting Group with Catalytic Copper (II) Chloride Dihydrate

t-Butyldimethylsilyl (TBDMS) ether can be cleaved upon refluxing in acetone/H2O (95 : 5) in the presence of a catalytic amount of copper (II) chloride dihydrate (5 mmol %).

An Efficient and Chemoselective Deprotection of tert-Butyldimethyl-silyl Protected Alcohols Using SnCl_2·2H_2O as Catalyst

An efficient and selective method for the deprotection of primary alcoholic tert-butyl-dimethylsilyl (TBS) ethers using SnCl_2·2H_2O as catalyst is described. The reaction conditionsallow primary alcoholic TBS ethers to be desilylated chemoselectively in the presence of phenolicTBS ethers, secondary and tertiary alcolholic TBS ethers, and the extensively used TBDPS-,acetyl-, benzyloxycarbonyl-, p-toluenesulfonyl- and benzyl protective groups.

A Mild and Efficient Method for the Synthesis of Acylals from Aromatic Aldehydes and Their Deprotections Catalyzed by Synthetic Phosphates under Solvent-Free Conditions

An efficient and clean preparation of acylals from aromatic aldehydes in the presence of synthetic phosphates (flourapatite and hydroxyapatite doped with ZnCl2 and ZnBr2) and acetic anhydride was achieved easily in high yields (86% - 97%) at room temperature under solvent-free conditions. Deprotection of the resulting acylals has also been attained by using the same catalysts under microwave irradiation. This method consistently has advantage of excellent yields (82% - 96%) and a short reaction time (3 - 4 min).

DEPROTECTION OF ACETALS AND KETALS WITH CpTiCl_3-KI

When the mixture of CpTiCl_3-KI is used, many acetals and ketals, which are difficuitly deprotected with CpTiCl_3 alone, can be easily converted to the corresponding carbonyl compounds in high yield at 30℃ in Et_2O.

Solvent-Free Mechanochemical Deprotection of N-Boc Group

Boc protection group could be readily removed in a very mild mechanochemical conditions. In a short reaction time, ball milling of Boc-protected amines with p-toluenesulfonic acid in solvent-free conditions affords corresponding amine p-TsOH salts.

Boc-苯丙氨酸叔丁酯选择性脱保护工艺研究

被保护的氨基酸化合物作为药物分子中间体和功能材料中间体得到广泛使用。Boc保护的氨基酸酯类化合物在脱除Boc保护时的高效性,可为其在整条工艺中的后续转化提供重要的先决条件。以Boc-苯丙氨酸叔丁酯为原料,对其选择性脱除Boc保护基而保留叔丁酯保护基生成苯丙氨酸叔丁酯盐酸盐的工艺进行了研究。结果表明,在室温或低温条件下,采用酸性条件脱保护的方式,收率可达到82%左右;反应条件简单、温和,工艺设备成本低廉,此工艺具有操作简单、经济实惠和绿色环保的特点。

气相中2-甲氧基乙酸参与9-芴甲氧羰基脱除反应的质谱研究

本研究主要探讨气相条件下,乙酸(HAc)、3-甲氧基丙酸(MPA)和2-甲氧基乙酸(MAA)在氨基酸保护基9-芴甲氧羰基(Fmoc)脱除过程中的作用。采用自制的纳喷装置将反应溶液依次雾化进入质谱仪,在线监测3种羧酸分别与不同氨基酸底物反应的关键离子,探讨羧酸与底物结构对复合物形成及质谱解离模式的影响。结果表明,对于同一氨基酸结合不同羧酸的复合物,只有相对含量较高的MAA复合物发生了解离。这可能是因为MAA 2号位的甲氧基促进了MAA与Fmoc基团9号碳上H的复合,降低了该H解离过渡态能垒,从而有利于MAA与Fmoc保护的氨基酸(X_(f),X_(f)=G_(f),A_(f),V_(f),L_(f),M_(f),F_(f),P_(f))形成的复合物[X_(f)+MAA-H]-阴离子中Fmoc的解离。对于MAA的不同氨基酸复合物而言,N上没有H的P_(f)复合物阴离子[P_(f)+MAA-H]-解离的碎片是以Fmoc脱除产物为主,其他氨基酸的MAA复合物则以丢失中性MAA碎片为主。可见,羧酸结构和氨基酸底物结构对复合物分子的形成和复合物分子中Fmoc的解离有着重要影响,该研究结果有助于理解气相中Fmoc解离的分子离子反应过程。

矢车菊素半合成方法实验教学实践

使用槲皮素为原料,在室温条件下采用羟基保护、羰基还原和酸化成盐脱保护三步反应合成了天然活性成分矢车菊素。使用薄层色谱、紫外、液质联用和红外光谱技术来监测反应和表征产物。实验原理简单,操作简便,底物与产物最大吸收波长差异大。实验过程颜色变化明显,实验总产率为51.74%。矢车菊素应用广泛,通过合成实验可有效引导学生将有机化学基本理论学以致用,激发学生学习兴趣和提高实验技能。

唑尼沙胺的新合成方法

以1,2-苯并异噁唑-3-甲磺酸钠盐为起始物料,经过氯化亚砜酰氯化,叔丁胺酰胺化保护,并在盐酸条件下脱去叔丁基,粗品经过甲醇精制,最终得到目标化合物唑尼沙胺(Zonisamide)。产物经^(1)H NMR、^(13)C NMR、MS及XRD进行结构确证,该合成工艺条件温和、操作简便、三废量少,且产品质量好,适合工业化生产。

Simple and Efficient Method for Deprotection of Tetrahydropyranyl Ethers by Using Silica Supported Sodium Hydrogen Sulphate

Tetrahydropyranyl （THP） ethers have been efficiently and simply deprotected by using Silica supported sodium hydrogen sulphate （NaHSO4-SiO2） in methanol at room temperature to regenerate the parent alcohols in high yields.

The synthesis, deprotection and properties of poly(γ-benzyl-L-glutamate)

With dicy- clohexylamine as initiator, the influence of monomer concentration, and reaction temperature and time on the polymerization of BLG NCA was examined. Three reagents were used for the deprotection of benzyl groups in PBLG, including hydrobromic acid/acetic acid (33 wt.%), NaOH aqueous solution and trimethylsilyl iodide (TMSI). Through examining the molecular weight of PLGA obtained using different deprotection methods, it was revealed that TMSI could minimize chain cleavage in the process of deprotection and retain the degree of polymerization. The biocompatibilities of PBLG obtained using different initiators were evaluated by a live/dead assay against L929 fibroblast cells. The in vitro cytotoxicities of PLGA obtained using different deprotecting agents were evaluated by a methyl thiazolyl tetrazolium assay. The results revealed that both PBLG and PLGA exhibited good biocompatibilities.

2,3-二甲基纤维素的制备与表征

以溶解的纤维素为原料,三苯氯甲烷作为定向取代试剂取代纤维素的6位羟基,制备6-三苯甲基纤维素。采用^(13)C-NMR、FT-IR对其进行了表征,结果表明三苯基氯甲烷实现了纤维素6位羟基完全取代。以6-三苯甲基纤维素作为原料,通过甲基化,脱除三苯甲基保护基团,制备了2,3-二甲基纤维素,采用13C-NMR、GC-MS、FT-IR等表征方法对样品进行了表征,并考察了反应温度与时间、甲基化试剂与糖结构单元摩尔比对2,3-二甲基-纤维素取代度的影响。结果表明,^(13)C-NMR、GC-MS两种表征方法表征2,3-二甲基-纤维素的取代分布具有较好的一致性,2,3-二甲基-纤维素取代度随着反应温度的升高、反应时间的延长、甲基化试剂与糖结构单元的摩尔比提升呈一定的递增关系。

侧链型聚醚二醇的制备及在WPU中的应用

先将丙酮与三羟甲基丙烷(TMP)在一定条件下反应将TMP分子的2个羟基保护起来,得到单羟基化合物(TA),然后以TA为起始剂进行环氧乙烷开环聚合及甲基封端反应,再对其进行羟基脱保护得到侧链型聚氧化乙烯二醇,并以此为原料合成水性聚氨酯。探究了羟基保护、封端工艺及羟基脱保护工艺条件变化对产品性能的影响。筛选出最佳的羟基保护工艺条件为:以固体酸为催化剂,丙酮质量分数为反应物总质量的45%;封端工艺条件为:NaOH质量分数为5.5%,一氯甲烷质量分数为5.5%;羟基脱保护工艺条件为:加水量为总质量5%,反应时间为6 h。合成的水性聚氨酯具有较好的耐酸、碱、盐稳定性。

一种基于双硫醚转化为醛的新型Hg^(2+)荧光探针

报道了一种新型的易于合成的反应型Hg^(2+)荧光探针,根据汞离子可以使缩硫醛脱保护生成相应醛的设计合成了一个二硫醇衍生物荧光探针,在乙腈-柠檬酸缓冲溶液中,Hg^(2+)使探针发生了明显的荧光光谱变化。荧光光谱实验结果表明,探针对Hg^(2+)表现出较强的选择性和抗干扰能力。探针对Hg^(2+)的检测限达到了5.7×10^(-7)mol/L。其识别机理通过核磁、荧光和质谱等方法验证。同时探针成功地应用于自来水中Hg^(2+)的检测。

天冬酰胺类抗体-药物偶联物连接子的合成新工艺

为了提高抗体-药物偶联物(Antibody-drug conjugate,ADC)的连接子4-N-(N-(L-丙氨酰-L-丙氨酰)-N′-三苯甲基-L-天冬酰胺酰基)-氨基苯甲醇(NH_(2)-AAN(Trt)-PAB)的合成效率,设计了一条新的合成路线。以N-芴甲氧羰基-N′-三苯甲基-L-天冬酰胺为起始原料,经过氨基酸缩合、氨基脱保护4步反应,高效合成了NH_(2)-AAN(Trt)-PAB。LCMS、1H NMR分析表征结果表明成功合成了NH_(2)-AAN(Trt)-PAB。该研究具有操作简便、条件温和可控、合成效率高、总产率较高等特点,有利于NH_(2)-AAN(Trt)-PAB的放大生产及其在ADC药物研发中的应用,同时对其他蛋白酶可裂解连接子的合成具有借鉴意义。

β-环糊精促进环己酮肟水解脱保护生成环己酮

利用β-环糊精对有机物的增溶和活化性能将β-环糊精应用于环己酮肟水解脱保护反应,系统地研究了β-环糊精催化性能、反应温度、β-环糊精的量、酸的用量和种类等对环己酮肟水解脱保护反应的影响。实验结果表明,β-环糊精通过和酸共同作用,可以显著地催化环己酮肟脱保护反应,在60℃β-环糊精加入时,反应的收率从73%提高到92%。酸及其添加的量对反应也具有明显作用,强酸对脱保护反应的效果明显优于弱酸。