Efficient Conversion of Tetrahydropyranyl (THP) Ethers to Their Corresponding Thiocyanates With in-situ–Generated Ph3P(SCN)2

Immediate and efficient one-pot conversion of tetrahydropyranyl (THP) ethers to their corresponding thiocyanates by in-situ–generated Ph₃P(SCN)₂ is described. Primary and secondary alkyls and also benzylic THP ethers are converted to their corresponding thiocyanates in excellent yields at room temperature by this method.     

Simple Protocol for Synthesis and Cleavage of Tetrahydropyranyl Ethers Using FeSO4 as an Inexpensive Catalyst

Protection and deprotection of alcohols and phenols as tetrahydropyranyl ethers (THP ethers) using an hydrous FeSO₄ under microwave irradiation without solvent is carried out.     

Bi(III) SALTS AS NEW CATALYSTS FOR THE SELECTIVE CONVERSION OF TRIMETHYLSILYL AND TETRAHYDROPYRANYL ETHERS TO THEIR CORRESPONDING ACETATES AND FORMATES

ABSTRACT

Bi(III) salts such as BiCl₃, Bi(TFA)₃ and Bi(OTf)₃ were found to be efficient catalysts for the transformation of trimethylsilyl (TMS) and tetrahydropyranyl (THP) ethers to their corresponding acetates and formates with acetic acid and ethyl formate. Selective acetylation and formylation of TMS and THP ethers of alcohols in the presence of phenolic TMS and THP ethers make this method a useful and practical procedure in organic synthesis.     

Chlorodiphenylphosphine as Highly Selective and Efficient Reagent for the Conversion of Alcohols,Tetrahydropyranyl and Silyl Ethers to Thiocyanates and Isothiocyanates

Abstract

A simple, highly selective and efficient method is described for the conversion of primary alcohols, tetrahydropyranyl and silyl ethers to thiocyanates by use of chlorodiphenylphosphine and ammonium thiocyanate. Secondary substrates produce both the two isomeric products, thiocyanate and isothiocyanate, while tertiary ones give isothiocyanates as the only products by this new method. In contrast to previously reported methods based on trivalent phosphorus for this transformation, the present method does not require an electrophile in the presence of trivalent phosphorus (ClPPh₂). The order of activity of these substrates is silyl ether> alcohol > tetrahydropyranyl ether. The present method not only interestingly distinguishes between primary, secondary and tertiary substrates but also converts them to the corresponding thiocyanates with excellent chemoselectivity in the presence of several other functional groups.     

Solvent-Free NaHSO4-SiO2-Catalyzed Efficient Tetrahydropyranylation of Alcohols and Phenols

A simple and efficient tetrahydropyranylation of alcohols and phenols has been developed using NaHSO₄-SiO₂ (0.5 mol%) as a catalyst under solvent-free conditions to yield corresponding tetrahydropyranyl ethers in excellent yields.     

Anhydrous ferric chloride adsorbed on silica gel induced ring enlargement of tertiary cyclobutanols : Synthesis of isolaurolene and derivatives,campholenic ether and (±) cuparene

The reagent obtained by mixing anhydrous FeCl₃ and silica gel induced, in dry medium, dehydration and specific C₄ → C₅ ring enlargement of tertiary cyclobutanols, cyclization of olefinic alcohols and cleavage of tetrahydropyranyl ethers.     

4-Aminophenyl Diphenylphosphinite (APDPP) as a Heterogeneous and Acid Scavenger Reagent for Thiocyantion or Isothiocyanation of Alcohols and Protected Alcohols

4-Aminophenyl diphenylphosphinite (APDPP) as a heterogeneous phosphinite reagent is used for the efficient conversion of alcohols, trimethylsilyl- and tetrahydropyranyl ethers, α -hydroxy phosphonates, and α -trimethylsilyloxyphosphonates to their corresponding thiocyanates or isothiocyanates in the presence of Br ₂ and NH ₄ SCN.     

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.     

Anhydrous ferric chloride dispersed on silica gel induced ring enlargement of tertiary cycloalkanols. II : a convenient homologation of cycloalkanones,preparation of spiro systems and propella -γ-lactones

The reagent obtained by mixing anhydrous FeCl₃ and silica gel induced, in the lack of any solvent, dehydration of tertiary cycloalkanols, specific C₄→C₅ and C₅ →C₆ enlargement, formation of spiro compounds and propella-γ- lactones and cleavage of tetrahydropyranyl ethers.     

Caro's Acid Supported on Silica Gel. Part V: A Mild and Selective Reagent for Conversion of Trimethyl Silyl ethers to the Corresponding Hydroxy Compounds

Mild and efficient method for deprotection of silyl ethers to alcohols is described using Caro's acid supported on silica gel. Reactions are carried out in dichloromethane at room temperature and their parent hydroxy compounds obtained in good to excellent yields. Using this procedure, tetrahydropyranyl ethers (THP) remain intact during desilylation reaction.

     

Poly(4-Vinylpyridinium P-Toluenesulfonate) as a Polymer-Supported Catalyst for Hydrolysis of Tetrahydropyranyl Ethers

Poly(4-vinylpyridinium) p-toluenesulfonate is used as an immobilized catalyst for the hydrolysis of tetrahydropyranyl ethers. This method is mild, efficient and convenient, giving the corresponding products in good to excellent yields and purity.     

Selective tetrahydropyranylation of alcohols and phenols using titanium(IV) salophen trifluoromethanesulfonate as an efficient catalyst

Titanium(IV) salophen trifluoromethanesulfonate, [Ti^IV(salophen)(OSO₂CF₃)₂], as a catalyst enables selective tetrahydropyranylation of alcohols and phenols with 3,4‐dihydro‐2H‐pyran. Using this catalytic system, primary, secondary and tertiary alcohols, as well as phenols, were converted to their corresponding tetrahydropyranyl ethers in high yields and short reaction times at room temperature. Investigation of the chemoselectivity of this method showed discrimination between the activity of primary alcohols in the presence of secondary and tertiary alcohols and phenols. This heterogenized catalyst could be reused several times without loss of its catalytic activity. Copyright © 2016 John Wiley & Sons, Ltd.     

Microwave-assisted preparation of imidazolium-based tetrachloroindate(III) and their application in the tetrahydropyranylation of alcohols

Microwave-assisted preparation of 1-alkyl-3-methylimidazolium tetrachloroindate(III), [Rmim][InCl₄] (R = methyl, ethyl, butyl, hexyl, octyl) and their application as recyclable catalysts for the efficient and eco-friendly protection of alcohols to form tetrahydropyranyl (THP) ethers are described.     

Preparation of thiocyanates and isothiocyanates from alcohols, thiols, trimethylsilyl-, and tetrahydropyranyl ethers using triphenylphosphine/2,3-dichloro-5,6-dicyanobenzoquinone (DDQ)/n-Bu4NSCN system

A combination of triphenylphosphine (PPh₃) and 2,3-dichloro-5,6-dicyanobenzoquinone (DDQ) provides a safe and easily available mixed reagent system for the conversion of 1° and 2° alcohols, thiols, trimethylsilyl-, and tetrahydropyranyl ethers to their corresponding thiocyanates and the 3° ones to isothiocyanates in good to high yields.     

A new diphenylphosphinite ionic liquid (IL-OPPh2) as reagent and solvent for highly selective bromination, thiocyanation or isothiocyanation of alcohols and trimethylsilyl and tetrahydropyranyl ethers

A new diphenylphosphinite ionic liquid (IL-OPPh₂) is introduced. This ionic liquid is used as both a reagent and a solvent to convert alcohols and trimethylsilyl and tetrahydropyranyl (THP) ethers into their corresponding alkyl bromides, thiocyanates or isothiocyanates in the presence of Br₂ and SCN⁻ at 80 °C. In this ionic liquid, bromination and thiocyanation of alcohols occurs highly selectively in the presence of trimethylsilyl and THP-ethers and also between different classes of alcohols. The use of this ionic liquid allows easy separation of the desired products from the phosphinate by-product.     

Direct conversion of trimethylsilyl and tetrahydropyranyl ethers into their bromides and iodides under neutral conditions using N-bromo and N-iodosaccharins in the presence of triphenylphosphine

Trimethylsilyl and tetrahydropyranyl ethers were easily converted into their corresponding bromides and iodides with high efficiency and selectivity by N-bromo- and N-iodosaccharins in the presence of triphenylphosphine under neutral conditions. The reaction of trimethyloctyloxysilane as a model compound was studied in different solvents with different ratios of silyl ethers, triphenylphosphine and N-halosaccharin at room temperature, in order to optimize the reaction conditions.     

Dicyanoketene Ethylene Acetal as a Mild and Efficient Catalyst for Tetrahydropyranylation of Alcohols

Alcohols can react with 3,4-dihydro-2H-pyran in the presence of a catalytic amount of dicyanoketene ethylene acetal under neutral conditions to afford the corresponding tetrahydropyranyl ethers in good yields.     

Direct synthesis of carbonyl compounds from THP ethers with IBX in the presence of β-cyclodextrin in water

Water, an environmentally friendly reaction medium, has been utilized for the oxidative deprotection of tetrahydropyranyl ethers 1 with IBX at room temperature in the presence of β-cyclodextrin to give the corresponding carbonyl compounds 2.     

A Simple and Convenient Method for the Deprotection of Tetrahydropyranyl Ether Using Iodine in Methanol

A simple and efficient method for the -deprotection of tetrahydropyranyl and 4,4′-dimethoxytrityl ethers using iodine in methanol is described.     

Facile Tetrahydropyranylation of Alcohols and Phenols Using Anhydrous Calcium Chloride under Mild and Neutral Conditions

Summary.  Treatment of 3,4-dihydro-2H-pyran with various alcohols and phenols in the presence of a catalytic amount of anhydrous calcium chloride in dichloromethane furnished tetrahydropyranyl ethers under almost neutral conditions. Corresponding author. E-mail: bandgar_bp@yahoo.com Received January 25, 2002; accepted (revised) March 20, 2002