Sharif Digital Repository

A simple and sensitive spectrophotometric method is proposed for the simultaneous determination of protocatechuic acid and protocatechuic aldehyde. The method is based on the difference in the kinetic rates of the reactions of analytes with [Ag(NH3)2]+ in the presence of polyvinylpyrrolidone to produce silver nanoparticles. The data obtained were processed by chemometric methods using principal component analysis artificial neural network and partial least squares. Excellent linearity was obtained in the concentration ranges of 1.23-58.56 ?g mL-1 and 0.08-30.39 ?g mL-1 for PAC and PAH, respectively. The limits of detection for PAC and PAH were 0.039 and 0.025 ?g mL-1, respectively  

The solid LiClO4-mediated one-pot reaction of aldehydes with secondary amines and C nucleophiles afforded the corresponding aminoalkylation products in high yields. Unlike the previous reported procedure, the aminoalkylation of aldehyde was achieved in the presence of only 0.5 equivalents of solid lithium perchlorate in dichloromethane as the solvent with good to high yields at room temperature. © Springer-Verlag 2003  

Several aminovinyl phosphonates were prepared in good yield by four-component aminoalkylation of aldehydes with diethyl(trimethylsilyl)amine, triethylphosphite and dimethyl acetylenedicarboxylate mediated by a 5 molar solution of lithium perchlorate in diethyl ether  

An efficient method for the synthesis of 4-amino-5-pyrimidinecarbonitriles by the three-component reaction of malononitrile, aldehydes, and N-unsubstituted amidines under aqueous conditions using CuO microspheres as catalyst is reported. The catalyst exhibited remarkable reusable activity. Graphical abstract: [Figure not available: see fulltext.]  

Red mud (RM) which emerges as a by-product from the alumina producing process has been used as an efficient catalyst for one-pot direct synthesis of nitrile compounds from aldehydes and hydroxylamine hydrochloride under microwave irradiation. ©ARKAT USA, Inc  

A one-pot high yielding reductive amination of aldehydes with primary and secondary amines using LiClO4/NaBH4 and LiClO 4/LiAlH4 as reducing agents in diethyl ether is described  

Various aldehydes have been protected with different thiols as dithioacetals with excellent yields using anhydrous copper sulfate as a mild and chemoselective catalyst. The reaction is carried out in a solvent and/or under solvent-free conditions. The transthioacetalization of oxyacetals into dithioacetals was also achieved in an excellent yield. Copyright © Taylor & Francis Group, LLC  

CuSO4/SiO2 is found to be an efficient and selective medium for the acetalization of aldehydes in the presence of ketones in solvent-free conditions under microwave irradiation. © 2005 Bentham Science Publishers Ltd  

An efficient, highly chemoselective and simple synthesis of secondary amines via reductive amination of aldehydes, aromatic amines and inexpensive and easily accessible Diethyl 2,6-dimethyl-1,4-dihydro-3,5-pyridinedicarboxylate (DHP) in the presence of catalytic amounts of p-toluenesulfonic acid (PTSA) in water in good to excellent yields is reported  

Aromatic aldehydes and ketones are readily acetalized or ketalized under microwave irradiation in the presence of water as a solvent  

A chemoselective synthesis of tetraketone and xanthene derivatives, by means of tandem Knoevenagel condensation and Michael addition in choline chloride-based deep eutectic solvents (DESs), is presented. The reaction of readily available aldehydes and active methylene compounds in malonic acid- and ZnCl2-based DES gives various xanthenes derivatives with good to excellent yields under mild reaction conditions. On the other hand, tetraketones were synthesized in almost quantitative yields by simple condensation of an aldehyde and active methylene compounds in milder deep eutectic solvents of urea and SnCl2. In addition, the reaction of other types of choline chloride-based DES leads to a... 

Synthesis of 14-aryl or alkyl-14H-dibenzo[a,j]xanthenes using nano-TiO 2 as eco-friendly and efficient catalyst is reported. Short reaction times, high yields, a clean process, simple methodology, easy work-up and green conditions are advantages of this protocol  

Under solvent free conditions between 40-50 °C, BF3.SiO 2, a mild solid acid catalyst, is applied to regio-chemo and stereoselective Claisen-Schmidt condensation. The procedure is very simple and the products are isolated with an easy workup in good to excellent yields  

An efficient and highly chemoselective synthesis of symmetrical secondary amines via reductive amination of aldehydes with inexpensive and commercially available HMDS and sodium borohydride in high to quantitative yields is reported. © 2008 Elsevier Ltd. All rights reserved  

Herein we report a new organocatalyst for the asymmetric Michael addition of nitroalkanes to α,β-unsaturated aldehydes. This catalyst incorporates a basic imidazole group in addition to the secondary amine responsible for activation of the α,β-unsaturated carbonyl compounds via iminium ion formation. The new organocatalyst is capable of catalyzing the enantioselective carbon-carbon bond formation with a high degree of enantiocontrol providing products in enantiomeric excesses of up to 92% and yields of up to to 91 %. These results constitute the best results so far reported for organocatalyzed Michael additions of nitroalkanes to α,β-unsaturated aldehydes, and provide proof of principle that... 

A simple, rapid, atom economy and highly efficient procedure has been developed for thiolysis of epoxides by aromatic and aliphatic thiols under solvent-free conditions. A high regioselectivity in favor of nucleophilic attack at the benzylic carbon atom of aromatic epoxides, such as styrene oxide, is observed. However, aliphatic unsymmetrical alkenyl oxides undergo selective nucleophilic attack at the sterically less hindered carbon atom. A variety of β-hydroxy sulfides were obtained in short reaction time and excellent yields with nearly complete regioselectivity. © 2005 Elsevier B.V. All rights reserved  

One-pot, three-component, Mannich reaction of naphthols with in situ prepared imines in 5 M ethereal lithium perchlorate at room temperature affords the corresponding aminoalkylated products in high yields with high diastereoselectivities. The process is exemplified by the reaction of 2-naphthol with (R)-1-phenylethylamine and an aromatic aldehyde in concentrated ethereal lithium perchlorate solution, which affords a highly diastereoselective access to the requisite 2-aminoalkylated product. © 2003 Elsevier Science Ltd. All rights reserved  

The synthesis of a variety of 2,3-disubstituted quinolines has been achieved successfully via a one-pot three-component reaction of arylamines, arylaldehydes and aliphatic aldehydes in the presence of butylpyridinium tetrachloroindate(III), [bpy][InCl4], ionic liquid as a green catalyst and solvent. Mild conditions with excellent conversions, and simple product isolation procedure are noteworthy advantages of this method. The recyclability of the ionic liquid makes this protocol environmentally benign  

In this study, 1,4-diazabicy lo[2.2.2] octane (DABCO) tribromide was immobilized on silica support by using 3-chloro propyl trimethoxy silane to obtain a silica-supported DABCO tribromide reagent. The synthesized reagent was characterized with elemental analysis, FT-IR spectroscopy, and thermo-gravimetric analysis (TGA). This reagent has been applied in the conversion of alcohol to corresponding carbonyl compounds. Alcohol oxidation reactions yield in 52-95%, and the reagent may be recycled five times with further bromine treatment