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.     

Highly efficient protection of alcohols as trityl ethers under solvent-free conditions,and recovery catalyzed by reusable nanoporous MCM-41-SO3H

An efficient method was developed for the protection of alcohols as trityl ethers using triphenylmethanol in the presence of nanoporous MCM-41-SO₃H as a heterogeneous catalyst under solvent-free ball-milling at room temperature. Low catalyst loading, high efficiency, reusability are among the advantages of this new solvent-free and environmentally friendly method. The deprotection of the produced trityl ethers was also efficiently achieved using the same catalyst in wet acetonitrile.     

Oxidative Deprotection Of Trimethylsilyl and Tetrahydropyranyl Ethers and Ethylene Acetals With Benzyltriphenylphosphonium Peroxomonosulfate in the Presence of Bismuth Chloride Under Non-Aqueous Conditions

Abstract

Benzyltriphenylphosphonium peroxomonosulfate (BnPh₃P⁺HSO₅ ^?) (1) is used as a new reagent for oxidative deprotection of trimethylsilyl and tetrahydropyranyl ethers and ethylene acetals to afford carbonyl compounds in refluxing acetonitrile in the presence of bismuth chloride.     

Selective deacylation of peracylated ribonucleosides

A protocol for chemoselective deprotection of N,O-acylated ribonucleosides has been developed. Peracylated pyrimidine ribonucleosides subjected to guanidinium nitrate and NaOMe in MeOH/CH₂Cl₂ at 0 °C undergo high yielding O-deacylation, while even more pronounced chemoselectivity is observed with peracylated purine ribonucleosides as O5′-acyl groups are preserved. Nucleobase-protecting groups (A^Bz, C^Bz, G^iBu, and U^Bz) are stable to these conditions, rendering this reagent mixture as a valuable addition to the collection of protecting group protocols in nucleoside chemistry.     

Application of Odorless Thiols for the Cleavage of 2‐ and 4‐Nitrobenzenesulfonamides

Several odorless or faint‐smelling thiols were tested to cleave 2‐ and 4‐nitrobenzenesulfonyl groups, which are widely utilized for selective protection and activation of amines. p‐Mercaptobenzoic acid (7) was found to be the most useful thiol for cleaving the o‐ and p‐nosyl groups in terms of ease of separation of the product from the workup residue, reaction temperature, and reaction time.     

Environmentally benign deprotection of dithioacetals using 30% hydrogen peroxide catalyzed by Fe(acac)3 and sodium iodide

The reaction of dithioacetals with 30% hydrogen peroxide in the presence of catalytic amounts of iron(III) acetylacetonate and sodium iodide efficiently produced the corresponding carbonyl compounds in high yields.     

Methyl 2-methoxytetrafluoropropionate as a synthetic equivalent of methyl trifluoropyruvate in the Claisen condensation. The first synthesis of 2-(trifluoroacetyl)chromones and 5-aryl-2-hydroxy-2-(trifluoromethyl)furan-3(2H)-ones

2-(Trifluoroacetyl)chromones and 5-aryl-2-hydroxy-2-(trifluoromethyl)furan-3(2H)-ones were obtained in good yields via the Claisen condensation of acetophenones with methyl 2-methoxytetrafluoropropionate, followed by sulfuric acid-mediated deprotection of the reaction products.     

A new protection group strategy for cellulose in an ionic liquid: simultaneous protection of two sites to yield 2,6-di-O-substituted mono-p-methoxytrityl cellulose

Increased reactivity of cellulose in ionic liquids was revealed when cellulose was protected with a 4-methoxytrityl moiety in the imidazolium-based ionic liquid, 1-allyl-3-methylimidazolium chloride ([amim]Cl). Selectively protected 2,6-di-O-(4-methoxytrityl)cellulose was obtained in one reaction step with a DS of close to 2, and was characterised by NMR.     

Remarkably Fast Deprotection of Semicarbazones and Tosylhydrazones Under Mild,Neutral and Solvent‐Free Conditions

Rapid and selective regeneration of carbonyl compounds from their semicarbazones and tosylhydrazones was carried out using hexamethylenetetramine‐bromine (HMTAB) and N‐bromosuccinimide (NBS). Good to excellent yields, mild, neutral and solvent‐free conditions are important features of this method.     

Deprotection of oximes using urea nitrate under microwave irradiation

A new mild and efficient method for the cleavage of oximes to carbonyl compounds using readily available urea nitrate in acetonitrile-water (95:5), under microwave irradiation within 2 min, in good yields is reported