Letters in Organic Chemistry - Volume 8, Issue 1, 2011

(γ-L-Glutamyl)putrescine and N1- and N8-(γ-L-glutamyl)spermidines, possible regioisomeric products of the polyamine glutamyl transferase of bacteria such as Escherichia coli and Pseudomonas aeruginosa, were synthesized from N-Boc-protected putrescine and 1,3-propanediamine.

Copper(II) triflate mediated three-component [4+2]-cycloaddition reactions between anilines, benzaldehydes and trans-anethole or trans-isoeugenol are reported. A simple and efficient one-pot method for the synthesis of diverse 2,4-diaryl-1,2,3,4-tetrahydroquinolines under mild conditions in the presence of catalytic amounts (10 mol %) of Cu(OTf)2 was developed. Attempts toward an asymmetric imino Diels-Alder reaction are discussed.

The intermediate phosphorus ylides which were prepared by reaction between triphenylphosphine and imidazole-4-carbaldehyde in the presence of acetylenic diesters produce dialkyl 5H-pyrrolo[1,2-c]imidazole-5,6- dicarboxylate derivatives via intramolecular Wittig reaction.

The synthesis of some new compounds exhibiting two 1,3-perhydrooxazine units connected to the same aromatic ring and of their ditosylated derivatives was carried out in good yields by the direct condensation reaction of the corresponding aminoalcohols with aromatic dicarbonyl compounds. The stereochemistry and the ring-chain tautomerism of these compounds were investigated by NMR and EI-MS.

The alkylation of cresol and its analogues was accomplished by quaternary onium salts under solventless and microwave (MW) conditions using Cs2CO3 as the base. The beneficial energy absorbing ability of the onium salts could be clearly observed under MW conditions as compared to the thermal experiments and was relevant in the range of 110- 125 °C.

Eco-benign method for synthesizing arylidene barbiturates has been developed by using ammonium chloride (NH4Cl) in stoichiometric amount, as an enolization activator, in water. Execution of methodology is simple, products obtained in high yields and the reactions are completed within 30 min. The new methodology does not involve any solvent/solvent extraction while solid products were yielded in all cases which were filtered and washed.

The synthesis and proteolytic inhibitor function of two new tetrapeptides, MeOSuc-Ala-Pro-Ala-Val-CH2Cl (APAV) and MeOSuc-Ala-Pro-Ala-Leu-CH2Cl (APAL) are described. An examination of inhibitory activity using a realtime reverse transcription-polymerase chain reaction (RT-PCR) assay in the presence of proteinase K reveals that the APAL at a concentration of 0.5 mM allows a signal to be obtained for an exogenous target (“Xeno RNA”) at 29 cycles (i.e Ct = 29), whereas the MeOSuc-Ala-Ala-Pro-Val-CH2Cl (AAPV) control requires a 2-fold lower concentration (0.25 mM) to produce the same Ct. The other new analog APAV does not provide proteinase K inhibition under the same experimental conditions.

An efficient ZnO nano catalyst, which was readily prepared from Zn(CH3CO2)2, 2H2O and PVP by a chemical solution approach has successfully catalyzed N-tertbutoxy carbonylation of amines. The ZnO nanorods were successful and gave promising results for highly active and chemoselective as well as easily recyclable catalyst for the NBoc protection reaction of a wide variety of amines. The catalyst could be easily recycled for five times without noticeable decrease in catalytic activity. The ZnO nanocatalyst was characterized with XRD and SEM.

We developed a facile synthesis process for producing optically active non-secosteroidal ligands (YR301-304), which are stereoisomers of LG190178, and evaluated their performance in transcriptional assays using mutant vitamin D receptor (VDR). It was found that all of them had stronger activities than the natural ligand 1α,25-dihydroxyvitamin D3 [1α,25(OH)2D3]. In particular, YR301 showed potent activity for both wild-type and mutant Arg274Leu VDR.

An efficient demethylation reaction for aromatic methyl ethers has been developed. Deprotection reactions give high yields with butylpyridinium bromide under microwave irradiation. Basic and acidic functional groups are tolerated if the reaction is performed under acidic conditions.

A number of α,β-unsaturated carboxylic acids were reacted with electron rich arenes or heteroarene in the presence of trifluoroacetic anhydride (TFAA) and H3PO4 at room temperature to give a variety of chalcone derivatives in good to excellent yields. The methodology was used to prepare novel compounds of potential pharmacological significances.

A series of the bis(3-indolyl)methene derivatives were synthesized and their anion binding and sensing properties in CH3CN or mixed CH3CN/H2O solution have been investigated in detail by UV-vis spectroscopic techniques. The deprotonation/protonation of the bis(3-indolyl)methene receptor is responsible for the dramatic color and spectral changes. The introduction of the electron-donating or withdrawing group into different moiety of the bis(3- indolyl)methene skeleton, which tunes the acidity of the H-bond donor moiety or the basicity of the H-bond acceptor moiety, has a positive effect on the selectivity and sensitivity of such “proton-transfer” chemosensors for anions.

(S,E)-2-(trimethylsilyl)ethyl 3-hydroxy-7-(tritylthio)hept-4-enoate was synthesized from commercially available L-malic acid by the Julia-Kocienski olefination coupling method. This method provides a concise synthetic strategy for (S,E) -3-hydroxy-7-mercaptohept-4-enoic acid.

The solid-phase synthesis of chitooligosaccharides is described. After the NHCbz trichloroacetimidate donors 6 and 14 were synthesized; solid-phase synthesis was performed using the Wang resin as support. The illustrated tetra-Nacetyl- chitotetraose 1 was obtained by iterative glycosylation reactions, catalytic hydrogenation, acetylation, and deacetylation, respectively.

A mild and efficient iodine-catalyzed direct substitution of hydroxy group of allylic, progargylic and other alcohols with various C- and N-nucleophiles was described in this contribution. C-C and C-N bond formations could be readily achieved by non-metallic and green catalysis for various compounds. This facilitates access to possible transformations of a broad scope of substrates into bioactive and pharmaceutically important building blocks.