An efficient and selective tosylation of alcohols with p-toluenesulfonic acid

Silica chloride has been found to be an efficient catalyst for facile tosylation of alcohols directly with p-toluenesulfonic acid in methylene chloride under reflux. The process is associated with selective tosylation of secondary alcohols over primary alcohols.     

Practical and Efficient Acylation and Tosylation of Sterically Hindered Alcohols Catalyzed with 1-Methylimidazole

Acylation of sterically hindered alcohols is frequently encountered in synthetic chemistry. An efficient and mild procedure for tosylation and esterification of sterically hindered hydroxyl groups with p-TsCl, Ac2O and Bz2O in the presence of 1-methylimidazole is described. It was observed that auxiliary base, triethylamine, accelerates the acylation reaction.     

General, robust, and stereocomplementary preparation of beta-ketoester enol tosylates as cross-coupling partners utilizing TsCl-N-methylimidazole agents

We have developed a general, robust, and cost-effective method for the (E)- or (Z)-stereocomplementary enol tosylation of beta-ketoesters using TsCl- N-methylimidazole (NMI)-Et3N or LiOH. TsCl coupled with NMI formed a highly reactive N-sulfonylammonium intermediate. Stereocongested secondary alcohols were smoothly sulfonylated using Ts(Ms)Cl-NMI-Et3N. beta-Ketoesters underwent (E)-selective tosylation using TsCl-NMI-Et3N and (Z)-selective tosylation using TsCl-NMI-LiOH (total of 23 examples; 60%-99% yield). Stereoretentive Negishi and Sonogashira couplings using enol tosylates proceeded successfully to give trisubstituted alpha,beta-unsaturated esters.     

Cobalt(II) catalyzed tosylation of alcohols with p-toluenesulfonic acid

Cobalt(II) chloride hexahydrate (CoCl₂·6H₂O) has been found to catalyze the tosylation of both aliphatic and aromatic alcohols with p-toluenesulfonic acid (p-TsOH) in high yields in 1,2-dichloroethane under reflux (ca. 80 °C). In the case of aliphatic alcohols, secondary alcohols undergo tosylation chemoselectively in the presence of primary hydroxy groups.     

Highly Efficient One-Pot Synthesis of N-Alkyl Sulfonamides from Alcohols Using N-(p-Toluenesulfonyl) Imidazole (Tsim)

Abstract

A facile and efficient method for one-pot synthesis of N-alkyl sulfonamides from alcohols using N-(p-toluenesulfonyl)imidazole (TsIm) is described. In this protocol, treatment of various potassium sulfonylamide salts and alcohols in the presence of TsIm and triethylamine in refluxing DMF furnishes the corresponding N-alkyl sulfonamides in good to excellent yields. This methodology is highly efficient for reaction of various structurally diverse primary and secondary alcohols as well as potassium sulfonylamides. Also, the density functional theoretical calculations are employed to mechanistically study this protocol.

[Supplementary materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements for the following free supplemental files: Additional text and figures.]     

A Simple and Effective Method for Catalytic Oxidation of Alcohols Using the Oxone/Bu4NHSO4 Oxidation System

Russian Journal of Organic Chemistry - A simple and efficient procedure is reported for the oxidation of alcohols to carbonyl compounds with Oxone (potassium peroxymonosulfate) in the presence of...     

Facile oxidative conversion of alcohols to esters using molecular iodine

A simple, efficient, and high-yield procedure for the oxidative conversion of alcohols to various types of esters and ketones, with molecular iodine and potassium carbonate was successfully carried out.     

Hydrolysis of nucleic acids in single-cell protein concentrates using immobilized benzonase

Hydrolysis of nucleic acids for single-cell protein concentrates has been carried out in one step using immobilized benzonase on corn cob. The immobilization is carried out by tosylation of primary alcohols of cellulose of corn cob. The immobilized benzonase is more stable vs pH changes than native benzonase, but the same optimum values of [Mg(II)] and temperature are obtained. The DNase activity is greater than the RNase activity. The percentage of DNA is reduced to 3-6% and that of RNA to 50%. The protein loss is negligible (1%). The enzymatic activity per weight unit of enzyme is greater in the case of benzonase that in reported data for other nucleases insolubilized on corn cob by the same procedure.     

Graphite oxide: a simple and efficient solid acid catalyst for the ring-opening of epoxides by alcohols

A simple, efficient, and general procedure for the ring-opening of epoxides with various alcohols to give the corresponding β-alkoxy alcohols using graphite oxide (GO) as the catalyst, under very mild reaction conditions is described. The method proceeds in good to excellent yields and in short reaction times at room temperature under metal-free conditions.     

Potassium Dodecatungsto Cobaltate Trihydrate: A New Heterogeneous Catalyst for the Synthesis of Homoallylic Alcohols and Amines

A simple and efficient procedure has been developed for one-pot synthesis of homoallylic alcohols and amines in good to excellent yields using a variety of aldehydes, amines, and allyltributylstannane in the presence of a catalytic amount of potassium dodecatungsto cobaltate trihydrate (K₅CoW₁₂O₄₀ · 3H₂O) as a heterogeneous catalyst at room temperature. The catalyst exhibited remarkable reusability.     

Efficient and Selective Halogenation of Allylic and Benzylic Alcohols under Mild Conditions

Summary. A simple, mild, and high yielding procedure for the halogenation of allylic and benzylic alcohols using a combination of SOCl₂, benzotriazole, and potassium halides in DMF is described. The effectiveness of the protocol is manifested in its selectivity towards allylic and benzylic alcohols whereas other simple alcohols such as primary, secondary, and tertiary are found to be unreactive.     

Treatment of alcohols with tosyl chloride does not always lead to the formation of tosylates

Treatment of substituted benzyl alcohols with tosyl chloride resulted in the formation of the corresponding chlorides, not the usual tosylates. A series of experiments demonstrated that it was possible to predict whether chlorination or tosylation would occur for substituted benzyl alcohols and pyridine methanols. Treatment of electron withdrawing group-substituted benzyl alcohols with tosyl chloride gave the corresponding chlorides in moderate yields under mild conditions, which provided a simple way to directly prepare chlorides from alcohols.     

A new one-pot solvent-free synthesis of pyridinyl tosylates via diazotization of aminopyridines

A new, convenient, one-pot method for the synthesis of pyridinyl tosylates is developed. The procedure involves sequential diazotization/tosylation of aminopyridines with sodium nitrite and p-toluenesulfonic acid under solvent-free conditions in a water paste at room temperature.     

Mild and efficient barbier allylation reaction mediated by magnesium powder under solvent-free conditions

A novel and highly efficient synthesis of homoallylic alcohols is achieved by the allylation of carbonyl compounds using magnesium powder as mediator under solvent-free conditions. A series of aldehydes and ketones are converted to the corresponding homoallylic alcohols, the yields of the reaction is considerably high (85-98%). The procedure is environment benign, operationally simple and easy to scale up at room temperature.     

Ultrasound assisted synthesis of 5,9-dimethylpentadecane and 5,9-dimethylhexadecane--the sex pheromones of Leucoptera coffeella

Racemic 5,9-dimethylpentadecane and 5,9-dimethylhexadecane, the major and minor constituents, respectively, of the sex pheromone of Leucoptera coffeella, have been synthesized from citronellol in 56-58% overall yield through six steps. Ultrasound irradiation efficiently supported tosylation of alcohols (two steps) as well as the subsequent cross coupling reactions with the pertinent Grignard reagents (also two steps).     

Derivatisation of steroid hormones with t-butyldimethylsilyl imidazole

An efficient procedure for the derivatisation of hydroxyl and alpha,beta-unsaturated ketonic steroids using t-butyldimethylsilyl imidazole is described. The conditions which employ potassium acetate as a basic catalyst result in quantitative formation of BDMS ethers and greater than 96% yield of BDMS-enol ethers. Various mechanisms involving the catalysed and uncatalysed reactions of t-butyldimethylsilyl imidazole with alcohols and enols are also discussed. The mass spectra of the BDMS-enol ethers, in contrast to the BDMS ethers, are dominated by an intense molecular ion, which facilitates the quantitation of these derivatives in biological samples. An example of the method is shown by the determination of 4-androstene-3,17-dione in urine using a stable-isotope internal standard.     

A Novel Oxidizing Reagent Based on Potassium Ferrate(VI)(1)

A new, efficient preparation has been devised for potassium ferrate(VI) (K(2)FeO(4)). The ability of this high-valent iron salt for oxidizing organic substrates in nonaqueous media was studied. Using benzyl alcohol as a model, the catalytic activity of a wide range of microporous adsorbents was ascertained. Among numerous solid supports of the aluminosilicate type, the K10 montmorillonite clay was found to be best at achieving quantitative formation of benzaldehyde, without any overoxidation to benzoic acid. The roles of the various parameters (reaction time and temperature, nature of the solvent, method of preparation of the solid reagent) were investigated. The evidence points to a polar reaction mechanism. The ensuing procedure was applied successfully, at room temperature, to oxidation of a series of alcohols to aldehydes and ketones, to oxidative coupling of thiols to disulfides, and to oxidation of nitrogen derivatives. At 75 degrees C, the reagent has the capability of oxidizing both activated and nonactivated hydrocarbons. Toluene is turned into benzyl alcohol (and benzaldehyde). Cycloalkanes are also oxidized, in significant (30-40%) yields, to the respective cycloalkanols (and cycloalkanones). Thus, potassium ferrate, used in conjunction with an appropriate heterogeneous catalyst, is a strong and environmentally friendly oxidant.     

Oxidation of benzylic alcohols to their Corresponding carbonyl compounds using ceric ammonium nitrate (CAN)/Br?nsted acidic ionic liquid

A chemoselective and efficient procedure for the oxidation of alcohols to the corresponding carbonyl compounds is reported using ceric ammonium nitrate in the presence of 3-methylimidazolium hydrogensulfate as Br?nsted acidic ionic liquid ([Hmim]HSO₄) as the solvent under mild conditions. The use of non-toxic and inexpensive materials, straightforward procedure, short reaction times and good yields of the products are the major advantages of this method.     

Mild and efficient silylation of alcohols and phenols with HMDS using Bi(OTf)3 under solvent-free condition

A very efficient and mild silylation of alcohols and phenols with hexamethyldisilazane (HMDS) at rt is developed using Bi(OTf)₃ as the catalyst. Primary, secondary and tertiary alcohols as well as phenols are excellently converted into corresponding TMS ethers in a very short reaction time. This procedure can also be applied to large scale silylation for industrial application.     

Palladium-catalyzed chemo- and enantioselective oxidation of allylic esters and carbonates

The palladium-catalyzed oxidation of allylic esters and carbonates using a novel potassium nitronate has been developed. This method is highly chemoselective, leaving other esters, alcohols, thioethers, and amines undisturbed. The oxidation can be operated in two modes: an achiral mode, using either PPh3 or rac-2 as ligand, or a chiral and highly enantioselective mode, using 2 as ligand. The oxidative enantioselective desymmetrization of meso bis-esters provides a significantly shorter method to arrive at commonly used synthetic intermediates compared to other strategies. Highly efficient kinetic resolution is also possible using this methodology.