A Convenient Method for the Oxidation of Urazoles to Their Corresponding Triazolinediones Under Mild and Heterogeneous Conditions with Sodium Nitrite and Oxalic Dihydrate

A combination of oxalic acid dihydrate and sodium nitrite in the presence of wet SiO₂, was used as an effective oxidizing agent for the oxidation of urazoles and bisurazoles to their corresponding triazolinediones at room temperature with good yieldr.     

Silica Sulfuric Acid/Sodium Dichromate Dihydrate as an Efficient Heterogeneous Method for the Oxidation of Alcohols Under Mild Conditions

A combination of silica sulfuric acid and sodium dichromate dihydrate in the presence of wet SiO 2 were used as an effective oxidizing agent for the oxidation of alcohols to their corresponding aldehyde or ketone derivatives in dichloromethane or toluene with excellent yields.     

A Convenient Method for Production of Thionitrites and Disulfides Under Mild and Heterogeneous Condition

Thiols can be readily converted to their corresponding thionitrite with a combination of inorganic acidic salts and sodium nitrite in dichloromethane at room temperature. Disulfides result from the homolytic cleavage of the sulfur-nitrogen bond of the unstable thionitrite and subsequent coupling of the resultant thiyl radicals.     

An Efficient Method for the Oxidation of Urazoles Under Mild and Heterogeneous Conditions

A combination of inorganic acidic salts or silica gelsupported inorganic acids and sodium nitrite in the presence of wet SiO₂ was used as an effective oxidizing agent for the oxidation of urazoles and bis-urazoles to their corresponding triazolinediones under mild and heterogenous conditions in good yields. Silica gel supported nitric acid and ceric ammonium nitrate (CAN) are also capable of effecting these oxidations in the absence of sodium nitrite in moderate to good yields. Mg(HSO₄)₂ is a superior to all the aforementioned reagents in convenience, yield and purity of the isolated triazolinediones.     

An Efficient Method for N-Nitrosation of Secondary Amines Under Mild and Heterogeneous Conditions

A combination of inorganic acidic salts or silica gel supported inorganic acids and sodium nitrite in the presence of wet SiO₂ was used as an effective nitrosating agent for the nitrosation of secondary amines to their corresponding nitroso drivatives under mild and heterogeneous conditions in moderate to excellent yields. Mg(HSO₄)₂ and NaHSO₄ are superior to all the aforementioned reagents in convenience, yield and purity of the isolated nitrosoamines.     

An Efficient Method for the Oxidation of Hantzsch 1,4-Dihydropyridines to their Corresponding Pyridine Derivatives Under Mild and Heterogeneous Conditions

A combination of oxalic acid dihydrate and sodium nitrite in the presence of wet SiO₂ was used as an effective oxidizing agent for the oxidation of dihydropyridines to their corresponding pyridine derivatives at room temperature with excellent yields.     

Silica Sulfuric Acid as an Efficient Reagent for the Synthesis of Symmetrical Ethers Under Mild and Heterogeneous Conditions

A mild and efficient method for the synthesis of symmetrical ethers using silica sulfuric acid is reported. All reactions are performed under compeletly heterogeneous conditions in good to high yields.     

An Efficient Method for Sulfonylation of Amines,Alcohols and Phenols with N-Fluorobenzenesulfonimide Under Mild Conditions

A new and convenient procedure was developed for the preparation of sulfonamides and sulfonic esters using N-fluorobenzenesulfonimide(NFSI) as a novel phenylsulfonyl group transfer reagent. In this protocol, a broad range of functional groups were tolerated to give the corresponding sulfonamides or sulfonic esters in moderate to excellent yields. The synthetic strategy for sulfonamides formation proceeded efficiently even under base-, metal-and additive-free conditions with the advantages of operational simplicity, mild reaction conditions as well as short reaction time.     

硅胶硫酸:一种在温和及无溶剂条件下一锅法合成1,4-二氢吡啶的高效多相催化剂(英文)

A series of 1,4-dihydropyridines have been prepared by a one-pot condensation of aldehydes,ethyl acetoacetate,and ammonium acetate in the presence of a heterogeneous catalyst silica sulfuric acid at room temperature under solvent-free condition. This new protocol has the advantage of short reaction time and excellent yields,and is an environmentally benign route to the synthesis of 1,4-dihydropyridines.     

A Novel Method for Beckmann Rearrangement of Oximes with Silica Sulfuric Acid under Mild Condition

The conversion of ketoxime into corresponding amide, known as the Beckmann rearrangement, is a common method used in organic chemistry and is also a topic of current interest. It accomplishes both the cleavage of carbon-carbon bond and the formation of a carbon-nitrogen bond, and represents a powerful method particularly for manufacture ε-caprolactam in chemical industry. This reaction, however, generally requires high reaction temperature, strong Br?nsted acid and dehydrating media, causing …     

A Mild and Efficient Method for Tetrahydropyranylation/Depyranylation of Alcohols and Phenols Under Neutral Conditions

Alcohols and phenols are tetrahydropyranylated rapidly in high yields in the presence of lithium bromide and dichloromethane at room temperature. Deprotection of these THP ethers can also be effected readily by mere change of the solvent to methanol and refluxing with excess lithium bromide. Due to neutral reaction conditions employed, the method is also compatible with compounds having acid sensitive functional groups.     

Silica Chloride/NaNO 2 as a Novel Heterogeneous System for Production of Thionitrites and Disulfides Under Mild Conditions

Thiols can be readily converted to their corresponding thionitrites with a combination of silica chloride ( I ), wet SiO 2 and sodium nitrite in dichloromethane at room temperature. Disulfides result from the homolytic cleavage of the sulfur-nitrogen bond of the unstable thionitrite and subsequent coupling of the resultant thiyl radicals.     

An Efficient Catalytic Procedure for the Selective Oxidation of Sulfides to Sulfoxides by Citric Acid/Al(NO3)3.9H2O/MBr Under Mild and Heterogeneous Conditions

A wide range of aliphatic or aromatic sulfides are selectively oxidized to the corresponding sulfoxides using Al(NO₃)₃.9H₂O, citric acid and a catalytic amount of KBr or NaBr in the presence of wet SiO₂ (50% w/w)in CH₂Cl₂ under mild and heterogeneous conditions in good to high yields.     

Sulfated Zirconia: An Efficient Catalyst for Solvent-Free Synthesis of Silyl Ethers Under Mild Conditions

Oximes, allylic, aliphatic, aromatic, cyclic, acyclic, and hetero alcohols are silylated in short reaction times with good yields in the midst of a catalytic amount of sulfated zirconia solid acid catalyst and trimethylsilyl cyanide under nonbasic, solvent-free, and ambient temperature conditions. Selectivity toward O-silyl ether rather than N-silyl ether has been observed. This simple experimental procedure, combined with easy recovery and reusability of the catalyst, is expected to contribute to the development of a clean and environmentally friendly strategy for the synthesis of O-silyl ethers.     

Mild and Efficient Method for Oxathioacetalization of Carbonyl Compounds

An efficient procedure for the protection of carbonyl compounds into the corresponding 1,3‐oxathioacetal has been achieved using PAS as catalyst.     

An Efficient Method for the Preparation of Sulfonamides from Sodium Sulfinates and Amines

Sulfonamides have a special role on medicine due to their broad biological activities, as bacterial infections, diabetes mellitus, oedema, hypertension prevention and treatment. In addition, sulfonamides are also useful in herbicides and pesticides. Herein, we communicate an efficient strategy for the preparation of sulfonamides via NH₄I‐mediated amination of sodium sulfinates. This new method provides a general and environmentally friendly access to sulfonamide compounds and tolerates a wide range of functional groups.     

Oxalic Acid: An Efficient and Cost-Effective Organic Catalyst for the Friedländer Quinoline Synthesis under Solvent-Free Conditions

Summary. Oxalic acid is used as an efficient catalyst in the condensation of 2-aminoaryl ketones with carbonyl compounds leading to the formation of quinolines in excellent yields under solvent-free conditions. This methodology offers significant improvements for the synthesis of quinolines with regard to the yield of products, simplicity in operation, inexpensive reagents, and green aspects by avoiding toxic catalysts and solvents.     

A Mild and Efficient Method for the Carbethoxylation of Amines

3-Carbethoxy-1,3-thiazolidine-2-thione [CTT(2)] has been prepared by treatment of 1,3-thiazolidine-2-thione (3) with ethyl chloroformate and triethylamine. CTT(2) shows high reactivity towards the amines.     

Iodine-Catalyzed Mild and Efficient Method for the Synthesis of Chalcones

Molecular iodine is found to catalyze the condensation of acetophenones with various aromatic aldehydes to prepare chalcones.     

A Mild and Efficient Method for Selective Acetylation of Amines

Primary and secondary amines were acetylated under mild conditions by means of 3-acetyl-1,3-thiazolidine-2-thione [ATT(1)]. The reaction was successfully applied to selective acetylation of a primary amino group of diamines containing a primary and a secondary amino groups or exclusive N-acetylation of amino alcohols.