Letters in Organic Chemistry - Volume 4, Issue 7, 2007

A titanium enolate of N-thioglycolyl oxazolidinethione has been prepared and used for the synthesis of "Evans" syn aldol adducts, in good yield and high selectivity. Removal of the chiral auxiliary was accomplished by reduction to the corresponding 1,3-diols or by preparation of Weinreb amides.

Electron-poor alkenes undergo rapid conjugate addition with a wide range of amines in the presence of lanthanum trichloride at room temperature to produce the corresponding 2-amino compounds in excellent yields.

Synthesis of lactones 3 and 4 is reported in an attempt towards the synthesis of natural product feigrisolide B. Sharpless asymmetric epoxidation and Gillman epoxide opening reactions were used for the construction of the required framework containing two stereocentres. The lactones 3 and 4 revealed that the proposed structure for feigrisolide B is incorrect.

A simple, completely chemoselective, and convenient procedure for reductive amination of aldehydes and ketones using NaBH4 in the presence of H3PW12O40 in THF and under solvent-free conditions at ambient temperature is described.

A simple, convenient method was described here for preparation of pentasubstituted pyrroles derivative using Mn(OAc)3 2H2O or Mn(OAc)2 4H2O at atmosphere.

New process to synthesize hexanitrohexaazaisowurtzitane (HNIW) using ultrasounds in ionic liquid (IL) was developed. Effects of various parameters were investigated to optimize the synthesis conditions. Meanwhile, the mechanism of reaction was also discussed. It was observed that ultrasonically promoted reaction of tetraacetyldibenzylhexaazaisowurtzitane (TADBIW) to HNIW has exhibited significant enhancement in yield at ambient condition.

A highly efficient, environmental friendly, palladium (II) catalyzed ligand promoted Suzuki reaction in aqueous phase was developed in short reaction time (4 - 5 h) at room temperature. The key for such a successful catalytic system was the use of suitable amount of co-solvent in the aqueous phase and reuse of palladium catalyst.

1-Phenylbutane-1,3-dione was found to be an efficient novel ligand for copper-catalyzed formation of diaryl ethers. With this ligand methyl 4-iodobenzoate reacted with various phenols to give the corresponding diaryl ethers with reasonable yields and efficiency. The optimized reaction was carried out at 100 °C using 1,4-dioxane as solvent, Cs2CO3 as base, CuI as the catalyst and 1-phenylbutane-1,3-dione as the ligand.

The one-step synthesis of a new series of protected 6-alkyl- and 6-aryl-2-acetylamino-4(3H)-pyrimidinones, where alkyl = CH3; aryl = Ph, 4-CH3Ph, 4-FPh, 4-ClPh, 4-BrPh and 4-OCH3Ph from the reaction of 4-methoxy-1,1,1- trichloroalk-3-en-2-ones with 1-acetylguanidine in acetonitrile as solvent is reported. The acetylamino group of 2- acetylamino-4(3H)-pyrimidinones has also been hydrolyzed under three different conditions to afford the corresponding free 2-aminopyrimidinones.

The data in this paper show that 2,2,4,4,6-pentachloro-5-cyclohexene-1,3-dione (2, also named pentachlororesorcinol and PCR), a humic acid model, reacts with several chemicals related to drinking water chlorination, for example, NH2Cl, NaOCl, and NH3, leading to the formation of several unusual chlorinated organic products, most of which have never been reported in the literature. The syntheses and confirmation of structures are discussed in detail.

Several 1,3-thiazolidin-4-ones were synthesized by cyclocondensation reaction of 2-amino-1,3,4-thiadiazole, mercaptoacetic acid and various arenealdehydes in moderate to good yields. These compounds were characterized by 1H, 13C and 19F NMR. The antimalarial activity of thiazolidinones was evaluated in vitro against Plasmodium falciparum clone but none of them showed activity at maximum concentration (50μg/ml) used.

A convenient method was developed for the selective synthesis of chloromethylbenzylphosphonium salts (2a, b) or phenylenediphosphonium salts (3a,b) based on the reaction of dichloroxylenes (1a or 1b)) with phosphines.. The monophosphonium salt was selectively obtained in toluene and the diphosphonium salt was obtained in DMF.

1,4-Dichloro-1,4-diazoniabicyclo[2,2,2]octane bis chloride, prepared in high yield by the treatment of 1,4- diazabicyclo[2.2.2]octane in dichloromethane with chlorine gas, acts as a site-selective electrophilic chlorinating agent towards carbanionic substrates in the presence of a base. β-Diketones and β-ketoesters were chlorinated in efficient yield without using any base. 1,4-Diazabicyclo[2.2.2]octane can be recovered, rechlorinated and reused several times.

The synthesis of quinolin-2(1H)-ones derivatives through a condensation reaction of 2-amino-benzophenones with α-mthylene esters under microwave-assisted conditions in high yield is described.

A convenient eco-friendly procedure has been developed for the synthesis of novel quinoline derivatives by a simple one-pot reaction of substituted anilines with β-ketoesters under microwave irradiation without any solvent. A comparative study of reaction on solid support versus neat reaction is done. Neat reaction technology gives better yield in shorter reaction times and also cuts down the usage of solvent.

Aluminum hydrogen sulfate is introduced as an efficient and reusable catalyst for one- pot synthesis of β- Acetamido carbonyl compounds by a multicomponent condensation in high yields.