Copper-catalyzed 1,4-protosilylation and 1,4-protoborylation of enynic orthoesters for synthesis of functionalized 2,3-allenoates

Herein,copper-catalyzed 1,4-protosilylation and 1,4-protoborylation of enynic orthoesters have been developed.The enynic orthoesters as precursors of unstable enynic esters were applied to produce the functionalized 2,3-allenoate products.Meanwhile,the asymmetric 1,4-protosilylation of enynic orthoesters with Ph Me2Si-Bpin was also studied.The chiral monopyridine imidazoline ligand was efficient to provide the asymmetric 1,4-protosilylation products with high enantioselectivity.

Environmentally Benign Synthesis of Sugar Orthoesters Promoted by Anhydrous Sodium Acetate and Ultrasound

A convenient and alternative procedure for the synthesis of sugar orthoesters from glycosyl bromides with an- hydrous sodium acetate as base under ultrasound irradiation is described. Various sugar and sugar-sugar orthoesters were prepared in 70%-91% isolated yields.

An expeditious and one-pot synthesis of unsymmetrical 2,5-disubstituted-1,3,4-oxadiazoles under microwave irradiation and solvent-free conditions

A one-pot synthesis of some unsymmetrical 2,5-disubstituted-1,3,4-oxadiazoles via cyclocondensation of benzoylhydrazines with orthoesters under solvent-free and microwave conditions are described here. The reaction is efficiently catalyzed by silica- supported sulfuric acid as it provided the title compounds in high yields and relatively short times. The catalyst is reusable and can be applied several times without considerable decrease in the yields and rates of the reactions.

Properties of a New Dental Photocurable Matrix Resin with Low Shrinkage

In order to reduce the amount of volumetric shrinkage that occurs in dental composites as a result of curing,a new kind of dental matrix resin combining bisphenol-S-bis（3-meth acry late-2-hydroxy propyl）ether（BisS-GMA） with the expanding monomer unsaturated spiro orthoesters 2-methylene-1,4,6-trispiro[4,4] nonane （SOE） was prepared,with triethylene glycol dimethacrylate （TEGDMA） as diluent.CQ （camphorquinone） of 1wt% and DMAEMA （2-（dimethylamino） ethyl meth acrylate） of 2wt% were used as photoinitiation system to initiate the copolymerization of the matrix resins.The performance including volumetric shrinkage,degree of conversion and condition of the ring-opening reaction of SOE,as well as curing time and the tensile bond strength were investigated respectively by the dilatometer,Fourier transfer infrared,the universal testing machine,and so on.The ring-opening polymerization of SOE occurred.Meanwhile,the obtain copolymers were crosslinked.The matrix resin containing BisS-GMA and SOE showed a reduced amount of volumetric shrinkage at 1.52%,which is a promising strategy for obtaining a polymer with a low amount of volumetric shrinkage.Furthermore,the other properties were not compromised.

A rapid synthesis of isoxazolo[5,4-d]pyrimidin-4(5H)-ones under microwave irradiation with solid acid catalysis in solvent-free conditions

A rapid and efficient method for the synthesis of isoxazolo[5,4-d]pyrimidin-4（5H）-ones has been developed through cyclocondensation of 5-aminoisoxazole-4-carboxamides with orthoesters under conventional heating and solvent-free microwave irradiation with solid acid catalysis. In comparison, the reactions are faster and the yields are higher under microwave irradiation.

利用磁性可回收的Fe_3O_4纳米颗粒催化剂合成苯并咪唑的新方法(英文)

Magnetically recoverable Fe3O4 nanoparticles have been synthesized as a catalyst for the cyclocondensation of 1,2-phenylenediamines with orthoesters under solvent-free conditions.Catalyst loadings can be as low as 1 mol% to give high yields of the corresponding benzimidazole derivative at 80 °C.This green method offers significant advantages in terms of its simplicity,low catalyst loadings,high product yields,and non-toxic nature.The Fe3O4 nanoparticles were characterized by X-ray diffraction,transmission electron microscopy,and Fourier transform infrared spectroscopy.

A new route to the synthesis of thieno[2,3-d]pyrimidin-4(3H)-one derivatives catalyzed by 12-tungstophosphoric acid (H_3PW_(12)O_(40))

Heteropoly acid H3PW12040 （PW） has been used as an effective catalyst for the synthesis of thieno[2,3-d]pyrimidin-4（3H）-one derivatives. The present methodology offers several advantages, such as high yields, short reaction times, mild reaction condition and a recyclable catalyst with a very easy work up.

A new approach to the facile synthesis of 2-substituted-quinazolin-4(3H)-ones

A new approach to the facile synthesis of 2-substituted-quinazolin-4（3H）-ones and its derivatives using the condensation reaction of substituted 2-aminobenzamide and orthoesters is reported.

A Rapid Access to Novel and Known Benzimidazole Derivatives Using Silica Chloride as a Reusable Catalyst

A new application of silica chloride as an easily available and reusable solid acid catalyst for the synthesis of benzimidazole and its derivatives through the condensation of o-phenylenediamines and orthoesters under thermal and solvent-free conditions is described. This novel and eco-friendly method is very cheap and has many advan- tages including excellent yields, short reaction time, and simple work-up procedure.

Synthesis of Pyrazolo[3,4-d]pyrimidin-4-ones Catalyzed by Brensted-acidic Ionic Liquids as Highly Efficient and Reusable Catalysts

A convenient and efficient method for the synthesis of pyrazolo[3,4-d]pyrimidin-4-ones via heterocyclization reaction of 5-amino-lH-pyrazole-4-carboxamides with triethyl orthoesters using two BrCnsted-acidic ionic liquids, 3-methyl-l-（4-sulfonic acid）butylimidazolium hydrogen sulfate [MIM＋（CH2）4SO3H][ HSO4 ] or N-（4-sulfonic acid）butyl triethylammonium hydrogen sulfate [Et3N＋（CH2）4SO3H][ HSO4 ], as efficient homogeneous catalysts under solvent-free conditions is described.

KAI（SO4）2-12H2O （Alum） Catalyzed One-Pot Three-Component Synthesis of 2-Alkyl and 2-Aryl-4（3H）-quinazolinone under Microwave Irradiation and Solvent Free Conditions

Twenty 2,3-disubstituted-4（3H）-quinazolinones were synthesed by one-pot three-component method with isa- toic anhydride, orthoesters and amines as raw materials in the presence of KAI（SO4）2·12H2O （Alum） under micro- wave irradiation and solvent-free conditions. 6-Bromo-2-propyl-3-p-tolylquinazolin-4（3H）-one （4m）, 6-bromo-2- methyl-3-phenethylquinazolin-4（3H）-one （4n） and 6-bromo-2-ethyl-3-phenethylquinazolin-4（3H）-one （40） were characterized by IR, 1H NMR, 13C NMR and elemental analysis.