Optically Active Helical Poly[(S)-3-vinyl-2,2'-dihydroxy-1,1'-binaphthyl]:New Ligand for Asymmetric Addition of Diethylzinc to Aryl Aldehyde

Poly[(S)-3-vinyl-2,2'-dihydroxy-1,1'-binaphthyl](L*)was obtained by taking off the protecting groups of poly[(S)-3-vinyl-2,2'-bis(methoxymethoxy)-1,1'-binaphthyl](poly-1).L*was proved to keep a stable helical con-formation in solution.The application of helical L*in the asymmetric addition of diethylzinc to aldehydes has been studied.The catalytic system employing 10 mol%of L*and 150 mol%of Ti(OiPr)_(4) was found to promote the addi-tion of diethylzinc to a wide range of aromatic aldehydes,giving up to 99%enantiomeric excess(ee)and up to 93%yield of the corresponding secondary alcohol at 0℃.The chiral polymer can be easily recovered and reused with-out loss of catalytic activity as well as enantioselectivity.

Synthesis of O-glycosylα-aryl nitrones

α-Aryl nitrone are one of the most useful kinds of nitrones and have been extensively explored in recent years.However,the sugar moieties have not been introduced into these molecules before.We presented here an efficient synthesis ofα-aryl nitrone Oglycosides via condensation of N-substituted hydroxylamine and aryl aldehydes glycosides in benzene.

1-Heptanesulfonic acid sodium salt:One pot efficient synthesis of 2-aryl-1-arylmethyl-1H-1,3-benzo[d]imidazoles

Synthesis of 2-aryl-1-arylmethyl-1H-1,3-benzo[d]imidazoles by the reaction of o-phenylenediamine with substituted aromatic aldehydes in the presence of 1-heptanesulfonic acid sodium salt （10 mol%） at room temperature. The reactions were performed in acetonitrile：water （8：2）. The method was proved to be eco-friendly, convenient and the products were isolated with good yields （82- 90%）.

Synthesis of Triphenyltin 2-(1,2-Ethylenedithio) Methylene-3-Oxo-5-Aryl-4-Pentenoate

Under esterification conditions, 2-(1,2-ethylenedithio) methylene-3-oxo-5-aryl-4-pentenoic acid 3 afforded the decarboxylated products 4. The triphenyltin 2-(1, 2-ethylenedithio) methylene-3-oxo-5-aryl-4-pentenoates 5 were obtained in high yields when 3 reacted with triphenyltin hydroxide.

Ammonium metavanadate:A novel catalyst for synthesis of 2-substituted benzimidazole derivatives

Ammonium metavanadate （10 mol%） was found to be a useful catalyst for the synthesis of various 2-substituted aryl benzimidazoles. It was used as an oxidizing agent for the condensation of o-phenylenediamine with different substituted aryl aldehydes at room temperature in ethanol. The method was proved to be simple, convenient and the product was isolated with good yields （79-91%）.

DMP(1,1,1-Triacetoxy-1,1-dihydro-1,2-benziodoxol-3(1H)-one):A novel catalyst for synthesis of 2-substituted benzimidazoles derivatives

Various 2-arylbenzimidazoles were synthesized from o-phenylenediamine and aldehydes via one-step process using DMP （Dess-Martin-periodinane） reagent as an oxidant. The method was proved to be simple, convenient and the products were isolated with good yields （80-90%）. ？2009 Charansingh H. Gill. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.

Photoinduced generation of alkyl and phthalimide nitrogen radicals from N-hydroxyphthalimide esters for the synthesis of benzophenone-type bioisosteres

N-Hydroxyphthalimide(NHPI)esters have emerged as powerful sources of alkyl radicals generated by single-electron transfer,but homolysis of NHPI ester to produce an alkyl radical and a phthalimide nitrogen radical is still in its infancy.In this study,we developed a light-induced method for generation of alkyl and phthalimide nitrogen radicals from NHPI esters and subsequent reactions of the radicals with[1.1.1]propellane and aryl aldehydes for rapid generation of bicycle[1.1.1]pentane ketones.This method does not require metals or photosensitizers,features a broad substrate scope(90 examples)and excellent functional group tolerance,and can be used for the functionalization of structurally complex natural products and drugs.Mechanistic investigations indicate that the reaction involves photoinduced homolytic cleavage of the Cs_(2)CO_(3)-NHPI ester complex to produce alkyl and phthalimide nitrogen radicals and subsequent hydrogen atom transfer between the phthalimide nitrogen radical and the aldehyde to generate an acyl radical.

An efficient and eco-friendly synthesis of 14-aryl-14H-dibenzo[a,j]xanthenes using H_4[SiW_(12)O_(40)]as a heterogeneous and reusable catalyst under solvent-free conditions

A simple and efficient catalytic protocol for the synthesis of 14-aryl-14H-dibenzo[a,j]xanthenes via the one-pot condensation ofβ-naphthol and aryl aldehydes using silicotungstic acid（H_4[SiW_（12）O_（40）]） is reported.The present method offers several advantages such as high to excellent yields,short reaction times,recovery and reusability of catalyst,mild reaction conditions and easy workup procedures.

Ethylenediamine： A Highly Effective Catalyst for One-Pot Synthesis of Aryl Nitroalkenes via Henry Reaction and Dehydration

Ethylenediamine （H2NCH2CHeNH2） was found to be a highly effective catalyst for the condensation of aryl aldehydes with nitromethane （or nitroethane）. When 1%-2% （tool%） of ethylenediamine was used as the catalyst, the one-pot reaction of aryl aldehydes with nitromethane （or nitroethane） by refluxing for 3-10 h efficiently afforded various arylnitroalkenes la-ly in 85%-97% yields.

Improved microwave-assisted catalyst-free synthesis of9-aryl-5,9-dihydropyrimido[4,5-d][1,2,4]triazolo[1,5-a]pyrimidine-6,8(4H,7H)-dione derivatives

Agreen regioselective synthesis of some new and known 9-aryl-5,9-dihydropyrimido[4,5-d][l,2,4]triazolo[1,5-a]pyrimidine-6,8（4H,7H）-diones has been described via the microwave-assisted one-pot reaction of 3-amino-1H-1,2,4-triazoles,aromatic aldehydes and barbituric acids under solvent- and catalyst-free conditions.This operationally simple procedure is less laborious and provides a better scope than previously reported procedures.

Catalyst-free ultrasound assisted novel one pot pseudo five component synthesis of aryl-bis-[1H-pyrazol-5-ol-4-yl]methanes,het(aryl)-bis-[1H-pyrazol-5-ol-4-yl]methanes and their 1-phenyl derivatives in aqueous medium

An efficient,catalyst-free and eco-friendly ultrasound-assisted novel one-pot pseudo-five-component synthesis of aryl-bis-[1H-pyrazol-5-ol-4yl]methanes,het(aryl)-bis-[1H-pyrazol-5-ol-4yl]methanes and their 1-phenyl derivatives in water is reported.The products were obtained in excellent yield in shorter duration with high purity,by simple filtration.This synthetic methodology has been optimized and discussed herein.

Sulphamic Acid （H2NSO3H）-Catalyzed Multicomponent Reaction of β-Naphthol： An Expeditious Synthesis of Amidoalkyl Naphthols

Sulphamic acid （H2NSO3H） was found to be an efficient catalyst for the multicomponent condensation reaction of β-naphthol, aromatic aldehydes and urea or amides to afford the corresponding α-amidoalkyl-β-naphthols in good yields. The remarkable features of this new procedure are high conversions, short reaction time, clean reaction profiles and simple experimental and work-up procedures.

Highly Efficient Low Melting Mixture Catalyzed Synthesis of 1,8-Dioxo-dodecahydroxanthene Derivatives

A low melting citric acid-urea mixture was found to be a new and effective promoting medium for the environmentally friendly synthesis of 1,8-dioxo-dodecahydroxanthene derivatives by condensation of aromatic alde-hydes and cyclic 1,3-dicarbobonyl compounds. This deep eutectic solvent acts as both the reaction medium and catalyst, furnishing xanthenediones in high to excellent yields.