An Efficient and Chemoselective Deprotection of tert-Butyldimethyl- silyl Protected Alcohols Using SnCl2.2H2O as Catalyst

An efficient and selective method for the deprotection of primary alcoholic tert-butyl-dimethylsilyl (TBS) ethers using SnC12“2H20 as catalyst is described. The reaction conditions allow primary alcoholic TBS ethers to be desilylated chemoselectively in the presence of phenolic TBS ethers, secondary and tertiary alcolholic TBS ethers, and the extensively used TBDPS-, acetyl-, benzyloxycarbonyl-, p-toluenesulfonyl- and benzyl protective groups.     

NaBrO3/NaHSO4 · H2O as a Versatile Reagent System for the Oxidation of Benzylic Alcohols and Aldehydes

The oxidation of benzylic alcohols and aldehydes by NaBrO₃ is efficiently promoted in the presence of NaHSO₄ · H₂O. All reactions were performed under mild and completely heterogeneous conditions in good to high yields.     

Deprotection Chemistry Mediated by ZrOCl2 · 8H2O: An Efficient,Mild, and Green Method for the Conversion of Oximes to Carbonyl Compounds in Aqueous Acetone

Abstract

Less-toxic, moisture-stable, inexpensive, and ecofriendly zirconium oxychloride octahydrate (ZrOCl₂ · 8H₂O) in aqueous acetone (1:1) mediates the conversion of oximes to carbonyl compounds in moderate to good yields. This green methodology is applicable to both aldoximes and ketoximes with tolerance to >C?C<, -NO₂, -OH, and -Cl groups. The reaction and workup are simple.

Cu(NO3)2 · 3 H2O as an Efficient Reagent for the Chemoselective Trimethylsilylation of Primary Alcohols and Oxidation of Trimethylsilyl Ethers

Abstract

Cu(NO₃)₂ · 3 H₂O can be used as an efficient reagent for the chemoselective trimethylsilylation of primary benzylic and aliphatic alcohols with hexamethyldisilazane (HMDS). This reagent is also able to oxidize the obtained trimethylsilyl ethers to the corresponding carbonyl compounds in the presence of wet SiO₂ and KBr. In this study, all reactions are performed in the absence of a solvent and good-to-high yields are obtained.     

A New Method for the Reductive Cleavage of S-S Bond by the System of Cp2TiCl2/i-BuMgBr/THF and its Application in Synthesis of α-Alkylthio Carbonyl Compounds

The reduction of disulfides by Cp₂TiCI₂/i-BuMgBr/THF led to nucleophilic sulfides [Cp₂TiSR]. This species reacted with α-broroo carbonyl compounds to give α-alkylthio carbonyl compounds in high yields.     

Efficient Transition‐Metal‐Free Oxidation of Benzylic and Secondary Alcohols to the Carbonyl Compounds Using an N‐Bromosuccinimide/NH4Cl System

The oxidation of a variety of benzylic and secondary alcohols was achieved in excellent yields using an NBS/NH₄Cl system in aqueous acetonitrile (CH₃CN‐H₂O; 7/3 v/v) at 80°C under very mild conditions.     

Mild and Efficient Debromination of vic-Dibromides to Alkenes with FeCl3·6H2O/Indium System

The FeCl₃ · 6H₂O/indium system efficiently causes debromination of various dibromides to the corresponding alkenes in good to excellent yields under mild conditions.     

Efficient and Recyclable RuCl3 ⋅ 3H2O Catalyst Modified with Ionic Diphosphine for the Alkoxycarbonylation of Aryl Halides

A series of ionic (mono-/di-)phosphines ( L2 , L4 , and L6 ) with structural similarity and their corresponding neutral counterparts ( L1 , L3 , and L5 ) were applied to modulate the catalytic performance of RuCl₃ ⋅ 3H₂O. With the involvement of the ionic diphosphine ( L4 ), in which the two phosphino-fragments were linked by butylene group, RuCl₃ ⋅ 3H₂O with advantages of low cost, robustness, and good availability was found to be an efficient and recyclable catalyst for the alkoxycarbonylation of aryl halides. The L4 -based RuCl₃ ⋅ 3H₂O system corresponded to the best conversion of PhI (96 %) along with 99 % selectivity to the target product of methyl benzoate as well as the good generality to alkoxycarbonylation of different aryl halides (ArX, X=I and Br) with alcohols MeOH, EtOH, i-PrOH and n-BuOH. The electronic and steric effects of the applied phosphines, which were analyzed by the ³¹P NMR for ¹J³¹_P-⁷⁷_Se¹J measurement and single-crystal X-ray diffraction, were carefully co-related to the performance RuCl₃ ⋅ 3H₂O catalyst. In addition, the L4 -based RuCl₃ ⋅ 3H₂O system could be recycled successfully for at least eight runs in the ionic liquid [Bmim]PF₆.     

Chemoselective Reduction and Transesterification of α-Keto Propargylic Esters Mediated by NaBH4 and CeCl3 · 7H2O

An efficient one-pot synthesis of α -hydroxy propargylic esters by chemoselective reduction followed by transesterification using NaBH₄ in combination with CeCl₃ · 7H₂O is described.

Aluminium Chloride Hexahydrate (AlCl3 · 6H2O): An Efficient,Facile, Mild,And Highly Chemoselective Catalytic Deprotection of Tert-Butyldimethylsilyl (TBS) Ethers

tert-Butyldimethylsilyl (TBS) phenyl / alkyl ethers were cleaved to the corresponding efficiently parent hydroxyl compounds in good yields using catalytic amounts of AlCl₃ · 6H₂O by conventional or microwave-assisted heating in methanol or isopropanol solution. Intramolecular and competitive experiments demonstrated the chemoselective deprotection of TBS ethers in the presence of triisopropylsilyl and tert-butyldiphenylsilyl ethers.     

B2O3/Al2O3 as an Efficient and Recyclable Catalyst for the Synthesis of β-Amino Alcohols under Solvent-Free Conditions

A convenient and efficient procedure for the solvent-free synthesis of β-amino alcohols has been achieved via B₂O₃/Al₂O₃-promoted highly regioselective ring opening of epoxides with aromatic amines in good to excellent yields at room temperature. Additionally, the catalyst can be recycled without affecting the catalytic property.     

Oxidation of Ethers,Alcohols, and Unfunctionalized Hydrocarbons by the Methyltrioxorhenium/H2O2 System: A Computational Study on Catalytic C?H Bond Activation

A concerted mechanism that does not involve an ionic intermediate was revealed by a DFT study on oxidation of ethers, alcohols, and unfunctionalized hydrocarbons by methyltrioxorhenium/H₂O₂. Instead, C? H insertion occurs through hydride transfer and then turns into a hydroxide transfer/rebound in a concerted fashion. The picture shows selected frames from an intrinsic reaction coordinate scan from the transition state to the product for the oxidation of cis‐1,2‐dimethylcyclohexane.

     

Syntheses of new topology BTTB-based metal–organic frameworks in CH3CN/H2O mixed solvents

Three complexes, [Zn₂(BTTB)](H₂O)₅ [BTTB = 4,4′,4″,4′″-benzene-1,2,4,5-tetrayltetrabenzoate, also named 1,2,4,5-tetrakis(carboxyphenyl) benzene] (1), [Cd₂(BTTB)(H₂O)₅](H₂O)₃ (2) and [Mn₂(BTTB)(H₂O)₅](H₂O)₂ (3), have been synthesized under hydrothermal conditions in CH₃CN/H₂O. Structural analyses revealed that 1 has new topologies, i.e. nnu1 (nnu stands for Nanjing Normal University) or nnu2 depending on the different simplification schemes. Compounds 2 and 3 are isostructural and have a scu (square planar and cubical vertices) topology, which have not been reported for BTTB-based metal–organic frameworks. Thermal stability of 1–3, hydrogen adsorption/desorption properties of 2 and 3, and luminescent properties of 1 and 2 were investigated. Compounds 1–3 are stable in air.     

An Alternative Method for the Highly Selective Iodination of Alcohols Using a CsI/BF3·Et2O System

Abstract

A variety of allylic and benzylic alcohols have been converted into the corresponding iodides using cesium iodide (CsI) in the presence of boron trifluoride etherate (BF₃·Et₂O) in acetonitrile under mild conditions.     

Preparation and Crystal Structure of a Charge-transfer Complex between an Organic Substrate and Molybdosilicic Acid [(CH3)2NH(CH2)C6H5]4SiMo12O40·2CH3CN·H2O

The charge transfer complex N,N-dimethylbenzylamine which is between the molybdosilicic acid and organic substrate has been prepared. Yellow crystals of the title compound ([(CH3)2NH(CH2)C6H5]4SiMo12O40·2CH3CN·H2O) were synthesized from the mixture of water and acetonitrile. The single-crystal X-ray analysis reveals that the crystal crystallizes in triclinic system, space group P1 with a = 13.313(2), b = 14.673(2), c = 19.736(3)A,α= 86.22(1),β= 88.76(1),γ= 66.97(1)0, V = 3540.2(9) A3 and Z = 2. The anion has the Keggin structure. The Mo-O bond distances range from 1.675(3) to 1.691(3) A for the terminal oxygen atoms, 1.798(3) to 2.045(3)A for the bridging ones, and 2.328(3) to 2.361(3)A for those in the SiO4 tetrahedron. The Si-O bond distances fall in the range of 1.623(3)～1.630(3)A.     

Glycerin and CeCl3 · 7H2O: A New and Efficient Recyclable Reaction Medium for the Synthesis of Quinoxalines

An efficient and environmentally benign process for the synthesis of quinoxalines has been developed using glycerine–cerium chloride as a reaction medium. This method is applicable to a variety of diketones and 1,2-phenylenediamines to afford the corresponding quinoxaline derivatives in excellent yields. The reaction medium was recovered and reused for further reactions without any problem.     

FeCl3·6H2O/C: An Efficient and Recyclable Catalyst for the Synthesis of 2,3-Unsaturated O- and S-Glycosides

A novel method for synthesizing 2,3-unsaturated glycosides has been developed using a handy and eco-friendly immobilized catalyst, FeCl₃·6H₂O/C. A series of 2,3-unsaturated O- and S-glycosides were obtained for bioassay from corresponding 3,4,6-tri-O-acetyl-D-glucal and D-galactal in good to excellent yields (56%–99%) and high anomeric selectivity (α/β = 7:1 to >19:1). Furthermore, the catalyst was efficient on gram-scale reactions and recyclable for at least three times.     

Synthesis of Chloroesters by the Cleavage of Cyclic and Acyclic Ethers using La(NO3)3 · 6H2O as a Mild and Efficient Catalyst under Solvent‐Free Conditions

A mild and an efficient synthesis of chloroesters is described by the reaction of cyclic and acyclic ethers with acid chlorides in the presence of a catalytic amount of La(NO₃)₃ · 6H₂O under solvent‐free conditions, affording the corresponding chloroesters in excellent yields.     

Novel and Highly Efficient Protection of Aliphatic Alcohols and Phenols with Hexamethyldisilazane in the Presence of La(NO3)3·6 H2O

Aliphatic alcohols and phenols are protected with hexamethyldisilazane in the presence of lanthanum nitrate hexahydrate (La(NO₃)₃·6H₂O) in excellent yields at room temperature.     

Ceric Triethylammonium Nitrate [Ce(Et3NH)2l(NO3)6; An Efficient Oxidant for the Oxidation of Benzylic Alcohols and α-Hydroxy Ketones to Their Corresponding Carbonyl Compounds Under Mild Conditions

Ceric triethyl ammonium nitrate is prepared and used for the oxidation of benzylic alcohols, and α-hydroxy Retones to their corresponding carbonyl compounds in methylene chloride with high yields.