Letters in Organic Chemistry - Volume 8, Issue 3, 2011

The concise synthesis of fused bicyclic aminals by way of intramolecular rhodium-catalyzed C-H amination is reported as well as the evaluation of their reactivity as iminium precursors. In contrast to the well-studied N,O-acetal systems, the aminals synthesized were found to be particularly stable under reaction conditions used for nucleophilic addition.

Three-component reaction in water was used to prepare a series of triazole substituted trans-β-lactams from the corresponding trans-4-acetoxy-lactam, sodium azide, and alkynes via a Cu(I)-catalyzed click chemistry with base free. This highly stereo- and regioselective procedure is simple, clean and efficient.

A class of ionic liquid supported (ILS) (S)-pyrrolidine sulfonamide organocatalyst (1c), which was developed earlier in our lab, has been applied to a wider range of Michael addition reaction, involving various aryl-substituted nitroolefins and a series of aldehydes. Catalyst 1c catalyzes Michael additions in which only 2 equivalents of aldehydes to each equivalent of nitroolefin are required. With 10 mol% of ILS catalyst 1c loading, Read More

Thio-Claisen rearrangement of a number of 3-(4-aryloxybut-2-ynlthio)benzofurans has been achieved under very mild conditions to give 2H-benzo[b]thiopyrano[2,3-d]furans. Attempts at further thio-claisen rearrangement resulted in the occurrence of thermal [1s, 3a] sigmatropic shift.

Nine 2-(4-(2-heterocycloethoxy)phenyl)-1,2,4-triazolo[1,5-a] pyridines have been synthesized. The structures of all products were confirmed by 1H NMR and HRMS. The cytotoxic activities of these compounds were evaluated against human ovary cancer cell line (HO-8910) in vitro by MTT method. The preliminary results showed that compound 4e (IC50 0.11mM) and compound 4f (IC50 0.11mM) exhibited moderate activity Read More

New process to synthesize HMX from 3,7-dinitro-1,3,5,7- tetraazabicyclo[3,3,1]nonane (DPT) using ultrasound in ionic liquid was developed. The reaction has been carried out in ultrasonic bath and the effect of various parameters such as presence and absence of ultrasound, volume and type of solvent, temperature, concentration of nitrating agent has been investigated with the aim of obtaining the optimum conditions f Read More

3,4-Dihydropyrimidinones modified with N3-(acetoxymethyl) and (aroyloxymethyl) groups can be regioselectively obtained in good yields by reactions of 3,4-dihydropyrimidinones with paraformaldehyde and substituted benzoic acids/acetic acid, by a one-pot two-step strategy in the presence of chlorotrimethylsilane. The advantages of this method are the simple procedure, the high regioselectivity of the products, sh Read More

The reactions of benzodithiol-2-ones containing a 4-nitro group with NaHS led to mixtures of 6- aminobenzopentathiepines and 4-nitrobenzotrithiols. The product ratio and yields depend on the substituent in the aromatic ring. Based on the yields of benzopentathiepines, the following series of substituent efficiency can be inferred: CF3 >> F, Cl > CN. Aminobenzopentathiepines are probably formed via the intermediate benzotri Read More

Synthesis of 5-arylmethyl-5-phenylimidazolidine-2,4-dione (or 5-arylmethyl-5-phenyl-2-thioxoimidazolidin-4- one) via the reaction of 3-aryl-2,3-epoxyl-1-phenyl-1-propanone and urea (or thiourea) was carried out in 57-98% yields at 50 °C in EtOH in the presence of KOH under ultrasound irradiation. The procedure has the advantages of mild conditions, short reaction time and high yield.

An environmentally benign catalytic method for efficient synthesis of quinoxaline derivatives via the condensation reaction of 1,2-diamines and 1,2-dicarbonyl compounds using ZrOCl2.8H2O in EtOH as a standard green solvent under mild conditions has been developed. The reusability of the catalyst has been successfully examined without any noticeable loss of its catalytic activity.

A rapid, safe and efficient method for the synthesis of novel molecular tweezers with one chiral arm based on deoxycholic acid was reported. Ten new molecular tweezers have been synthesized in good yields. The structures of these new molecular tweezers were characterized by 1H NMR, IR, MS spectra and elemental analysis. These chiral molecular tweezers showed good enantioselectivity for D-amino acid methyl esters.

A number of BF2-chleate compounds were developed based on 4,6-dichloropyrimidine. The electron withdrawing ability of the -BF2 group markedly enhances the reactivity of the chlorides within chloropyrimidine. Consequently the BF2-chelate compounds can be modified in a variety of ways by nucleophilic substitutions. The compounds prepared in this work consist of 4,6-dichloropyrimidine and BF2-chelate moieties separated b Read More

Highly functionalized regio- and stereoisomers of 1,2,3-triazole-substituted cyclopentanes were prepared in six steps from either bicyclic β-lactam 7 or γ-lactam 23 by 1,3-dipolar cycloaddition of the azido cyclopentanol intermediates with acetylenes. The reactions of azido aminocyclopentanols with non-symmetric acetylenes resulted regioselectively in the corresponding 1,4-disubstitued triazole derivatives under both thermal an Read More