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.

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.

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).

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.

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

Diethylamine, di-n-hexylamine, dicyclohexylamine and triethylamine have been used as initiators for the ring-opening polymerization of γ-benzyl-L-glutamate N-carboxyanhydride （BLG NCA） to synthesize poly（γ-benzyl-L-glutamate） （PBLG）. The relationship between the molecular weight of PBLG and the molar ratio of monomer and initiator was studied. 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.

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.

Bioinformatics Analysis of 4-hydroxy-3-methyl-2-buten1yl diphosphate synthase(HDS) in Populus trichocarpa

[Objective] This study aimed to analyze the deprotection of acetyl group on amino group. [Method] A simple, convenient one-pot amino protection group of amide removed by thionyl chloride and pyridine via efficient chlorination and hydroly- sis with 1, 2-dichloroethane as solvent at ambient temperature has been developed. [Result] Pyridine is crucial to the reaction; the best solvent is 1, 2-dichloroethane, and the most suitable reaction temperature is the ambient temperature; in addition, the yield is the highest as the molar ratio of pyridine to N-（4-bromophenyl） ac- etamide is 1：1. [Conclusion] The significant features of this protocol include short re- action time, cleaner reaction profiles, under mild reaction conditions and easy purifi- cation, and simple workup that precludes the use of toxic solvents.

Highly Selective Preparation of 3-and 6-Modified Mannose/Altrose Derivatives

A highly efficient method to get 3-and 6-modified mannose/ahrose derivatives for oligosaccharide synthesis is described. All the compounds were obtained exclusively with the combinations of 3-and/or 6-hydroxyl protection and/or activation（ including the configuration conversion of 3-carbon atom）.

Synthesis and characterization ofα-butyl-ω-{3-[(2,2-dihydroxymethyl)-propionyloxy]}propylpolydimethylsiloxanes

A series of polydimethylsiloxanes containing two primary hydroxyl groups at one single chain end were synthesized by five-step reactions which included esterification,hydroxyl protection,anionic ring-opening polymerization,hydrosilylation and deprotection.The prepared compounds in each step were characterized.The results showed that each step synthesis was successfully carded out and objective products could be achieved.

Synthesis of Salmon Calcitonin Analogs Using Fmoc-based Chemistry on MBHA Resins

Peptide analogs of salmon calcitonin (sCT) were synthesized by using Fmoc-based chemistry on MBHA resins. Salmon calcitonin was modified by 1) cysteines at positions 1 and 7 were replaced by valine and alanine respectively to result in open chain analogs, 2) the glycine at position 30 was replaced by alanine, D-alanine and sarcosine respectively, and 3) some residues were deleted besides the above two modifications. A modified two-step deprotection / cleavage procedure, in which a solvent of TFA / TMSBr / thioanisole / EDT / m-cresol combines with HF cleavage, was adopted in SPPS.

An Efficient Cleavage of 1,3-Dioxolane Using ZnCl_2/THF/H_2O

A new. mild and efficient method for the cleavage of 1,3-dioxolane is reported.

Facile Preparation and Application of Polystyrylsulfonyl Chloride Resins

Polystyrylsulfonyl chloride resin (1) is a useful polymer intermediate in organic syntheses. Resin 1 can be obtained by chlorosulfonation of styrenedivinylbenzene copolymers, or treatment of the sulfonated copolymer derivatives (i. e., sulfonic cation exchange resins) with thionyl chloride, phosphorus oxychloride and phosphorus pentachloride. The preparation of polystyrylsulfonyl chloride have been reviewed by Emerson et al.

The Application of Allyl as a Protecting Group in the Preparation Of Dinucleoside Carbonate

Reaction of 5'-O-p-methoxytritylthymidine with 1,1'-carbonyl-diimidazole gave the 3'-O-carbonylimidazolide, which was condensed in high yield with 3'-O-protected thymidine to give a dinucleoside carbonate. In the synthesis of dinucleoside carbonate, allyl can be used as a good protecting group for 3'-hydroxyl of thymidine. The condition of deprotection will not affect the carbonate bridges.

Solvent-switchable Acetalization by Yb（OTf）3-Catalyzed Procedures

O,O＇Diethyl acetals were prepared in high yields under mild conditions via the reaction of triethyl orthoformate with aldehydes and ketones in absolute ethanol in the presence of as low as 0.1 tool% of Yb（OTf）3. Using the same catalyst in THF-H2O, these O,O＇-diethyl acetals could be converted to the corresponding carbonyl compounds efficiently. This new protection-deprotection protocol presents the advantages of ease of execution, high efficiency and good chemoselectivity.

A novel route for the synthesis of androgen receptor antagonist enzalutamide

A novel route of enzalutamide was developed in five steps.Starting from 4-amino-2-(trifluoromethyl)benzonitrile(7)and Boc-2-aminoisobutyric acid(16),condensation,deprotection,Ullmann coupling,cyclization and amination provided enzalutamide in 41.0%total yield.This route avoids the using of toxic chemical,unstable intermediate and high-risk reaction.It is a potential efficient and economical procedure for industrialization.