Synthesis of Galectin Inhibitors by Regioselective 3′-O-Sulfation of Vanillin Lactosides Obtained under Phase Transfer Catalysis

Vanillin-based lactoside derivatives were synthetized using phase-transfer catalyzed reactions from per-O-acetylated lactosyl bromide. The aldehyde group of the vanillin moiety was then modified to generate a series of related analogs having variable functionalities in the para- position of the aromatic residue. The corresponding unprotected lactosides, obtained by Zemplén transesterification, were regioselectively 3′-O-sulfated using tin chemistry activation followed by treatment with sulfur trioxide-trimethylamine complex (Men3N-SO3). Additional derivatives were also prepared from the vanillin’s aldehyde using a Knoevenagel reaction to provide extended α, β-unsaturated carboxylic acid which was next reduced to the saturated counterpart.

Diastereoselective Cyclopropanation by Using Camphorpyrazolidinone Derived α,β-Unsaturated Amides and Ylide

<p><b>Abstract:</b> High to moderate diastereoselectivity and high chemical yield are observed in the Michael addition of ylide and chiral camphorpyrazolidinone ylide to an optically pure a,b-unsaturated carboxylic acid derivatives derived from a chiral camphorpyrazolidinone and a,b-unsaturated carbonyl respectively. A novel route to the asymmetric synthesis of cyclopropanation derivatives is described.</p>

Diastereoselective Cyclopropanation by Using Camphorpyrazolidinone Derived α,β-Unsaturated Amides and Ylide

<p><b>Abstract:</b> High to moderate diastereoselectivity and high chemical yield are observed in the Michael addition of ylide and chiral camphorpyrazolidinone ylide to an optically pure a,b-unsaturated carboxylic acid derivatives derived from a chiral camphorpyrazolidinone and a,b-unsaturated carbonyl respectively. A novel route to the asymmetric synthesis of cyclopropanation derivatives is described.</p>

Antifeedant Activity of Pyrazolin-5-One Derivatives

A series of substituted 4-{1-aza-2-[(aryl) amino)]}-3-methyl-2-pyrazolin-5-ones has been synthesized and evaluated for their biological activity. The title compounds (4a-l) were prepared by the diazotization of substituted anilines (1a-l) to form substituted phenyl hydrazine derivatives (2a-l) which synthesized substituted 4-{1-aza-2-[(aryl) amino)]}-3-methyl-2-pyrazolin-5-ones (4a-l) by Michael addition reaction, which is a nucleophilic addition of enolate anion to the carbon-carbon double bond of a α, β–unsaturated carboxylic acid derivatives. Twelve different pyrazolinone derivatives (4a to 4l) were synthesized. Structural assignments of these compounds have been made by elemental analysis, FTIR, 1HNMR and Mass spectral data and the purity of the compounds was determined by TLC. The antifeedant activity of the newly isolated heterocyclic compounds was evaluated against agriculture pest Achoea janata. Compound 4d found to be very effective as antifeedant while rest of the compounds showed a moderate to good degree of antifeedant activity.

Asymmetric hydrogenation of an α-unsaturated carboxylic acid catalyzed by intact chiral transition metal carbonyl clusters – diastereomeric control of enantioselectivity

Asymmetric hydrogenation catalysis by [(μ-H)2Ru3(μ3-S)(CO)7(μ-P–P*)] (P–P* = chiral diphosphine) indicates intact chiral clusters as active catalysts.

Catalytic hydrogenation of α,β-unsaturated carboxylic acid derivatives using copper(i)/N-heterocyclic carbene complexes

A simple and air-stable copper(i)/N-heterocyclic carbene complex enables the catalytic hydrogenation of enoates and enamides, hitherto unreactive substrates employing homogeneous copper catalysis and H2 as a terminal reducing agent.