A Coupling Reaction of 4-Amino-5-mercapto- 3-substituted-1,2,4-triazoles to Generate Symmetrically Substituted Hydrazines

Summary. A novel coupling reaction of 4-amino-5-mercapto-3-substituted-1,2,4-triazoles to generate symmetrically substituted hydrazines, N,N′-bis(5-mercapto-3-substituted-1,2,4-triazol-4-yl)hydrazines was unexpectedly observed. Five examples are presented to demonstrate this reaction. All isolated products were unambiguously characterized.     

Simultaneous deprotection–oxidation of cyclic hemiacetals: a fine ending for a Ueno–Stork ATRC to dichloro-γ-lactones

Recently we found that a copper catalysed Ueno–Stork cyclization can be a very useful means for the expedient synthesis of dichloro-γ-lactones, but, to take advantage of this step, the method still lacks of an efficient and selective follow-up. This Letter describes our progress in that field, unveiling the use of a supported and recyclable Cr^(VI) catalyst for the simultaneous deprotection and oxidation of cyclic dichloro hemiacetals.     

Facile Deprotection of 1,3‐Oxathiolanes to Carbonyl Compounds with O‐Iodoxy Benzoic Acid (IBX) in the Presence of β‐Cyclodextrin in Water

1,3‐Oxathiolanes are smoothly deprotected to carbonyl compounds by IBX at room temperature with β‐cyclodextrin as a catalyst and water as solvent.     

Novel Organophosphorus Reagents for the Synthesis of Amines

Abstract:

New organophosphorus equivalents of a² type N-protected amine synthons are presented.     

Convenient Procedure for Dethioketalisation in Nitrogen Heterocycles

Regeneration of Carbonyl compounds from the corresponding thioketals in nitrogen heterocycles have been effected using Dowex 50W acidic catalyst in reasonable yields.     

Gaseous Nitrogen Dioxide for Sustainable Oxidative Deprotection of Trimethylsilyl Ethers

Abstract

In this study, trialkylsilyl ethers of indispensable protected alcohols are oxidatively deprotected in neat form with gaseous nitrogen dioxide (NO₂). Quantitative yields of aldehydes or ketones are obtained without the necessity of chromatography. The byproducts, nitrogen monoxide, anhydrous nitric acid, and hexamethyldisiloxane, can be quantitatively separated by evaporation and distillation in closed systems for recycling or further use. The direct new method supersedes the previous techniques that produce dangerous wastes and require chromatographic workup, while the atmospheric gas NO₂ and its gaseous reduction products are easily kept in closed systems until further use.     

Zeofen: A User-Friendly Catalyst for Oxidative Cleavage of Tetrahydropyranyl Ethers Under Non-Aqueous Conditions

Summary.  Primary and secondary tetrahydropyranyl ethers are efficiently converted to carbonyl compounds in excellent yields by zeofen under non-aqueous conditions. Received November 21, 2000. Accepted (revised) January 9, 2001     

氯沙坦的合成

以2-丁基-4-氯-5-羟甲基咪唑和5-(4-溴甲基联苯-2-基)-1-三苯甲基-1H-四唑为原料,通过氮烷基化、脱三苯甲烷保护基和还原反应合成了抗高血压药氯沙坦,总收率64%,其结构经1H NMR表征。     

Benzyltriphenylphosphonium Peroxodisulfate (PhCH2PPh3)2S2O8: An Efficient and Convenient Reagent for the Oxidative Cleavage of Phenylhydrazones,Paranitrophenylhydrazones, and Semicarbazones to Their Parent Carbonyl Compounds

Deprotection of phenylhydrazones, paranitrophenylhydrazones, and semicarbazones to their parent aldehydes and ketones in high yields has been carried out using benzyltriphenylphosphonium peroxodisulfate as a selective oxidant under mild conditions.     

Hydroxyl group deprotection reactions with Pd(OH)2/C: a convenient alternative to hydrogenolysis of benzyl ethers and acid hydrolysis of ketals

Benzyl ethers, ketals and orthoformates were cleaved with Pd(OH)₂/C in methanol, to generate the corresponding alcohol; carboxylic acid esters were stable under these reaction conditions. Pd(OH)₂/C in methanol was used for the deprotection of hydroxyl groups during the preparation of sequoyitol via myo-inositol orthobenzoate. This method of deprotection has the potential to be useful in the synthesis of different classes of organic compounds since the reaction conditions do not involve strong acids, bases or hydrogen.