Letters in Organic Chemistry - Volume 4, Issue 1, 2007

New prostaglandins analogues, containing heteroatoms in the cyclopentane ring were synthesized. The key step in the synthesis was the preparation of the five-membered ring starting from L-cysteine ethyl ester hydrochloride. The addition of the alkyl groups at C-15 position was also performed.

Chiral derivative 3 has been recognized as a precursor of enantiopure 2,3-disubstituted piperidines. A study concerning the chemoselective reduction, using BH3.Me2S, of highly functionalised compounds 6 and N-BOC aminoacid 12 is reported.

Aryl and alkyl isoselenocyanates 2 react with ethyl γ-chloroacetoacetate (1) in the presence of triethylamine to give the corresponding 4-oxo-2-amino-4,5-dihydroselenophene-3-carboxylates 4a-f in moderate to good yields.

Miyaura-Suzuki reaction was carried out in water-ethanol solutions by using Pd/CaCO3 as catalyst. Very good yields were obtained using different bases, phosphates or carbonates. The catalyst was recycled up to seven times without any loss of activity. To evidence the presence of Pd(II) in solution as the true catalyst, the solids were removed by decantation and the reaction products were extracted with hexane. The water Read More

L-Proline has been found as an effective catalyst for the one pot synthesis of polyhydroquinoline derivatives via four component Hantzsch reaction. This method provides several advantages such as being environmentally benign, possessing high yields with increased variations of the substituents in the product and preparative simplicity.

Weinreb amides were conveniently prepared in high yields by reaction of carboxylic acids with N,Odimethylhydroxylamine hydrochloride at room temperature using triphosgene as an acid activator in the presence of triethylamine.

In the absence of any catalysts and additives, one-pot synthesis of 1,2,3-triazoles from benzyl and alkyl halides, sodium azide and alkynes in water was developed. The reactions of terminal arylalkynes, sodium azide with benzyl chlorides and bromides generated the corresponding regiospecific 1,4-disubstituted triazoles in excellent yields, but terminal aliphatic alkynes afforded the mixture of regioisomers (1,4- disubstituted and Read More

Susceptibilities of two bis-quinolizidine systems: 2-methylsparteine and 2-phenylsparteine to oxidation reaction using K3Fe(CN)6, KMnO4 and Hg(CH3COO)2 have been determined. Of these two derivatives only 2-methylsparteine has been found to undergo oxidation giving new 2-methyl-17- oxosparteine and 2-methyl-α-isosparteine. The structures of the new compounds have been established by IR, MS and NMR spectros Read More

A novel synthetic route has been developed for the preparation of pharmacologically remarkable (R)- (-)-2-methoxyapomorphine (2) and other 2-alkoxyapomorphines 8-10.

α,β-Dehydroamino amides are important intermediates for the synthesis of biologically active molecules. A rapid procedure is reported for the synthesis of α,β-dehydroamino amides from azalactones under MW radiation. Azalactones were produced via Erlenmeyer reaction and submitted to ring opening reactions under MW during 15-30 min. Over 90% yields were obtained.

The efficient multicomponent synthesis of 3,4-dihydropyrimidin-2(1H)-ones promoted by a heterogeneous Cu/silica xerogel composite is presented herein. This composite was synthesized by the sol-gel methodology employing CuCl2 as the metal source. The catalyst can be easily recovered and reused in subsequent reactions.

Some 1H-benzotriazoles have been synthesised in good yields in short times by reaction of ophenylenediamine with sodium nitrite in acetic acid under ultrasound irradiation. Also, the ultrasoundassisted preparation of 1-acylbenzotriazoles is described.

A green protocol involving novel three-component one-pot cyclocondensation reactions of 2- amino-4-aryl-thiazoles, aromatic aldehydes and ammonium thiocyanate under solvent-free microwave irradiation (MWI) conditions expeditiously yields thiazolo-s-triazine nucleobases, which afford the corresponding pyrano N-nucleosides on I2 promoted glycosylation with 1,2,3,4-tetra-O-acetyl- β-D-ribo- /xylopyranose under MWI fol Read More

The reaction between N-(thio)phosphoryl imines and diethylzinc was investigated in detail. For the imines bearing at least one P-O single bond, the corresponding reduction product was formed in excellent yield in nonpolar solvent toluene. In polar solvent, the reduction product was generated accompanied with partial formation of the alkylation product. The corresponding ethylating product became the predominant product in Read More

An efficient aza-Michael addition of amines to a series of α,β-unsaturated ketones, carboxylic esters, nitriles and chalcones has been carried out using perchloric acid supported over silica gel (HClO4-SiO2) at room temperature in high yields under solvent-free reaction conditions.

One-pot three-component condensation of aldehydes or ketones, amines and trimethylsilyl cyanide was accomplished in the presence of a catalytic amount of K5CoW12O40.3H2O as an efficient and reusable catalyst.

Mild and convenient method for deprotection and direct oxidative deprotection of silyl ethers to the corresponding hydroxy and carbonyl compounds is described using polyvinylpolypyrrolidone-bromine complex (PVPP-Br2). Selective oxidative deprotection of benzylic silyl ethers in the presence of primary aliphatic alcohols was also achieved at room temperature.

Biginelli-like scaffolds were synthesized in good yields by a three-component condensation reaction of 5,5-dimethyl-1,3-cyclohexanedione, an aldehyde and urea, N-methylurea or thiourea in 1-butyl-3- methylimidazolium bromide ([bmim]Br) as ionic liquid (IL) in the presence of silica sulfuric acid (SSA) as solid acid catalyst at 100 °C within less than 2 hours.