Investigation into Protective Groups for Anilino Functionality upon Oxone-Mediated Oxidative Esterification

In the course of organic synthesis, particularly for multi-step synthesis or natural product total synthesis, the selection of appropriate protective groups for the intended functionality is crucial in order to achieve chemoselective synthetic goals. The development of many useful protective groups has been reported based on the functionality of the anilino group. Herein, we discuss our study of various protective groups and the processes we used to establish compatibility with anilino functionality via the implementation of Oxone-mediated oxidative esterification in methanol. The results and the details of our experiments are reported herein.

The 3,4-dimethoxybenzyl group as solubilizing protective group for the in situ deprotection/deposition of extended aromatic thiolate monolayers

While self-assembled monolayers(SAMs)of aromatic thiolates are frequently used in a wide range of applications,their formation is often hampered by the low solubilities of their precursors.Here we introduce the 3,4-dimethoxybenzyl group as a protective group for the thiol moiety,which increases the solubility and stability of the precursor,but becomes cleaved off during monolayer formation,especially at elevated temperature(60°C)and in presence of protons(trifluoroacetic acid).For a series of substituted terphenylthiols as model systems,it could be demonstrated by using ellipsometry,infrared-reflection absorption spectroscopy,and scanning-tunneling microscopy that the resulting SAMs have the same structure and quality as the ones obtained from the respective unprotected thiols.The protective group has the additional advantage to be stable under Pdcatalyzed C–C bond formation reaction conditions,facilitating the syntheses of the respective precursors.

The Compatibility of Groups Used to Protect Phenolic Functionality during Oxone-Mediated Oxidative Esterification

Protecting groups often play an essential role in organic synthesis, particularly for multi-step synthesis or natural product total synthesis. Various protecting groups areavailable to mask the vulnerable functionality;phenolic hydroxy groups are noteworthy examples, but their stability differs when protected. Herein, the compatibility of protective phenolic functionality was investigated with the implementation of indium (III) triflate-catalyzed oxidative esterification using Oxone in methanol. A wide range of protective moieties was selected and subjected to Oxone-mediated oxidative esterification. For example, sulfonates were found to be sufficiently stable and inert whereas acetals were susceptible to reaction conditions. The details of this investigation are provided.

Academic Forum on Protection of Vulnerable Groups' Rights

On March 19, an academic forum was held in Jinan City, Shandong Province, on protection of vulnerable groups’ rights. Sponsored by the Law School of Shandong University, it gathered some 50 experts from the Central Patty School, Chinese Academy of Social Sciences, China Society for Human Rights Studies, Shandong Higher People’s Court, as well as some research universities in the country. Four subjects were discussed at the forum: definition of vulnerable groups, legal principles for protection of vulnerable groups’

Constitutional Values of Protecting Human Rights of Disadvantaged Groups

The confrontation between the disadvantaged and advantaged groups is eternal throughout the competition for survival. But the human spiritual world has its humane aspect in addition to competition. The concern for and protection of the disadvantaged group is the moral law characteristic of humanity, just as the Universal Declaration of Human Rights says in its Article 1： ＂All human beings are born free and equal in dignity and rights.

Enhancing hydrolytic stability of dynamic imine bonds and polymers in acidic media with internal protecting groups

Imine bonds are among the most explored building motifs in dynamic chemistry,polymers,and materials,and yet,their acid-resistance remains a longstanding issue.Herein we demonstrate a concept of internal protecting groups for improving the kinetic stability of dynamic imine bonds and polymers.Systematic examination of structure-reactivity relationship of a series of aldehydes/imines bearing a neighboring carboxyl allowed uncovering of required structural features for dynamically masking imine bonds with cyclic structures.Mechanistic studies indicated that noncovalent interactions along with sterics control the ringchain equilibrium and the stability of imine bonds.The incorporation of internal protecting groups into imine polymers further enabled their controlled stability in acidic media.Moreover,a combination of dynamic covalent network and coordination supramolecular network provided a facile means for the modulation of luminescent and mechanical properties of polymers.The strategies and results reported should be beneficial to molecular assemblies,dynamic polymers,biological delivery,and intelligent materials.

The Development of Human Rights Protection in Cross-border Personality Rights and Tort Conflict Laws

Personality rights are basic rights related to human dignity in the concept of human rights protection,and respect for personality rights is the basic prerequisite for safeguarding other human rights.Human rights protection exerts a profound impact on the value of legislation and enforcement practices of private international laws in the field of cross-border personality rights infringement in various countries,which is mainly manifested in the integration of substantive justice and the humanistic care concept of protecting the rights of vulnerable groups into formal justice,and expands the development space of human rights protection ideas in cross-border personality rights and tort conflict laws.the diversity of human rights protection values determines that cross-border personality rights infringement may lead to conflicts between personality rights and other basic rights,such as freedom of speech.to reconcile such conflicts,a workable method is to prioritize personality rights protection in accordance with the hierarchy of rights theory in the value judgment of public order reservation or to clarify the limits of the right holder’s tolerance obligation through the limited application of the principle of proportionality.China’s current cross-border personality rights and tort conflict law can optimize the protection of the rights of vulnerable groups by diversifying the options of available legal methods,and establish a balancing mechanism between personality rights and freedom of speech,so as to improve China’s legal protection system for human rights in the field of foreign-related civil and commercial affairs.

可重复使用的丙磺酸功能化纳米结构SBA-15上醇和酚与六甲基二硅氮烷的硅烷化反应(英文)

Various alcohols and phenols were trimethylsilylated in excellent yields using hexamethyldisilazane in the presence of catalytic amounts of environmentally friendly, hydrophobic, highly thermal stable, and completely heterogeneous sulfonic acid functionalized mesostructured SBA-15 in dichloromethane at ambient temperature. Primary, bulky secondary, tertiary, and phenolic hydroxyl functional groups were transformed to the corresponding trimethylsilyl ethers in excellent yields. The simple experimental procedure was accompanied by easy recovery and the catalyst was reusable (at least 18 reaction cycles); these are attractive features of this protocol.

Regioselective protection of 10-deacetylbaccatin Ⅲ and semi-synthesis of paclitaxel

Semi-synthesis of paclitaxel was achieved in four steps from 10-deacetylbaccatin HI （10-DAB HI）. The key steps are the regioselective protection at the hydroxyl group at C-7 of 10-DAB HI, using 1,1′-thiocarbonyldiimidazole as a selective reagent, and the deprotection of the protected paclitaxel with a mixture of p-toluenesulfonic acid and 0.1 mol/L aqueous hydrochloride.

A NEW POLYMER-BOUND 1,2-DIOL AS A PROTECTING AGENT FOR SYMMETRICAL DIALDEHYDE

A novel polymer-bound 1,2-diol, 3-polystyrylsulfonyl-1,2-propanediol (6) had been prepared by the reaction of sodium polystyrylsulfinate with allyl bromide, followed by oxidation and. hydrolysis or directly with 3-chloro-1,2-propanediol in the presence of a phase transfer catalyst, n-tetrabutylammonium iodide. The capacity of resin 6 for terephthaidehyde reached 1.43 mmol/g. The aldehydic groups attached to polymer 6 reacted with hydroxylamine hydrochloride or reduced by sodium borohydride giving p-formylbenzaldoxime (yield: 89%)and p-formyl-benzalcohol (yield: 734%), respectively. The high yields of these polymer-supported reactions showed that the polymer 6 possessed the effective isolation of its reactive sites.

A one-step procedure for facile, selective synthesis of protected d-glucopyranosides with free 2-C hydroxyl group starting from peracetylated β-D-glucopyranose

An important field in carbohydrate chemistry is to look for regioselective re-actions of saccharides to simplify the chemical synthesis of oligosaccharides. Oneof such efforts nowadays is directed to the convenient preparation of protected D-

Photolabile Protecting Group-Mediated Synthesis of 2-Deoxy-Glycosides

A green and efficient photolabile protecting group(PPG)-mediated glycosidation approach for the synthesis of 2-deoxy-glycosides is reported.By employing ortho-nitrobenzyl carbonate(oNBC)as PPG,N,N-dimethylformamide(DMF)-modulated SPhosAuNTf_(2)-promoted glycosidation with per-oNBC-protected 2-deoxy-glycosyl ynenoates affords the 2-deoxy-glycosides with moderate to excellentα-selectivities presumably depending on the reactivities of the acceptor alcohols.Based on the PPG-mediated glycosidation approach,oligosaccharides with three to six oNBC groups are effectively achieved.The multiple oNBC groups in the 2-deoxy-glycosides are completely cleaved by irradiation at 365 nm,resulting in the desired 2-deoxy-glycosides in an efficient manner without affecting the common alkyne,alkene,azide functional groups and the traditional protecting groups on the aglycones.

Aryl groups,supplement of amino protecting group chemistry!

Amino group protective strategy has consequently emerged in multistep organic synthesis.Easy and selective deprotection procedures are crucial to facilitate the chemical transformation.Recently,Zhang’s group from Henan Normal University collaborating with Chen’s group of Nankai University developed a novel strategy for the regiospecific cleavage of inert aryl C-N bonds in N-aryl amides by hypervalent iodine(V)reagents.These procedures allow removal of sort of aryl groups under mild conditions to give primary amides in high efficiency.It bestows these aryl groups with the characteristics of amino protecting groups that might be the supplement of amino protecting group chemistry.

MOHURD: 10 Cities as the First Group of Pilot Cities for Historic Building Protection

In order to fully practice the spirit of the 19th CPC National Congress,enhance the protection and inheritance of cultural heritage,and fully exert the utilization value of historic building,the Ministry of Housing and Urban-Rural Development(MOHURD)recently released the list of the first group of pilot cities for historic building protection,which include:Beijing,Guangzhou,Suzhou,Yangzhou,

Design,synthesis and bioassay of the emerging photo-responsive fungicides

Precise and spatiotemporal control over the pesticide remains to be a challenge.More efficient controlled release systems(CRSs)have been developed to support the precise delivery of active ingredients.Herein,we incorporated the photoremovable protecting groups(PRPGs)into phenamacril(PHE)and obtained two photo-responsive fungicides of NV-PHE and DEACM-PHE.The 4,5-dimethoxy-o-nitrobenzyl(NV)or 7-diethylaminocoumarin(DEACM)-caged PHE could release the active molecule PHE after irradiation of UV light and blue light,respectively.Optical properties and in-vitro/vivo fungicidal activities of NV-PHE and DEACM-PHE demonstrated the feasibility for light controlled release of PHE.DEACM-PHE could release 98%PHE by illumination of blue light.The irradiated DEACM-PHE could preserve the similar bioactivity of PHE,and significantly improve the in-vitro/vivo fungicidal activities compared to the non-irradiated DEACM-PHE.The optical controlled release of PHE from DEACM-PHE enabled the precise and spatiotemporal delivery of PHE,diversifying the development of CRSs for pesticide,and providing environmentfriendly agricultural applications with high pesticide efficiency.

GaI_3 Catalyzed Tetrahydropyranylation of Alcohols and Phenols

In dichloromethane, the nucleophilic addition of alcohols or phenols to 3,4-dihydro-2H-pyran (DHP) was cata-lyzed effectively by gallium triiodide which was generated in situ by the reaction of gallium metal and iodine to give the corresponding tetrahydropyranyl acetals in good to excellent yields.

A Facile Synthetic Approach to 3-Halo-4-substituted-l,5-dihydro-4H-1,2,4-triazoline-5-thiones Based on Retro-Michael Addition

A facile 3-step synthetic approach to 3-halo-4-substituted-l,5-dihydro-4H-1,2,4-triazolme-5-thiones （la--lk） from corresponding unhalogenated 8a---8i was developed based on the strategy of retro-Michael addition, with the key steps being regioselective S-alkylation of compounds 8a-8i with ethyl 3-iodopropionate（12c） and alkaline cleavage of the propionate protecting group via retro-Michael addition. The synthetic approach was characterized by simplicity of operation and wide substrate scope.

A novel approach towards dethioacetalization reactions with H_2O_2-SOC1_2 system

A simple and efficient protocol for the deprotection of dithioacetal,1,3-dithianes and 1,3-dithiolanes has been developed using H_2O_2-SOC1_2 reagent system.In addition to the absence of overoxidation products for oxidation-prone substrates,high chemoselectivity, the low cost and availability of the reagents,simplicity of the method,short reaction times,and excellent yields can also be considered as strong points for this method.

Methodology-driven efficient synthesis of cytotoxic(±)-piperarborenine B

The evolution of synthetic design toward the efficient synthesis of cyclobutane natural product(±)-piperarborenine B is demonstrated.Taking the advantages of good functional group compatibility of contractive synthesis of cyclobutanes from pyrrolidines,stereoselective synthesis of unsymmetric highly functionalized cyclobutanes core of(±)-piperarborenine B was realized in one step.Also,an unprecedented carboxylic acid assisted-diastereoselective Kracho decarboxylation/transmethylation features a new strategy for a non-symmetrical cyclobutane core.The synthesis of(±)-piperarborenine B illustrates the advancement of methodology resulting in the improvement in synthetic efficiency.

Preparation of twelve 1-methyl-2-formyl-5-substituted pyrroles and their hydrazones

Preparation of twelve 1-methyl-2-formyl-5-substituted pyrroles (2a–1), with five of them as new compounds, is described. Their derivatives, i.e., 1-methyl-2-formyl-5-substituted pyrrole phenyl hydrazones (3a–1) and 1-methyl-2-formyl-5-substituted pyrrole (4-nitrophenyl) hydrazones (4a–1) are all new compounds. They have also been prepared and further identified.