A regioselective palladium-free protocol for accessing unsymmetrical biaryls through ring transformation of 6-aryl-~-pyrones

A regioselective synthesis of unsymmetrical biaryls with electron withdrawing or donating substituents is described and illustrated by carbanion-induced ring transfonnation of 6-aryl-a-pyrones with methoxyacetone in excellent yield. Our methodology is an alternative to classical organometal-catalyzed aryl-aryl coupling reactions and can be applied to the synthesis of functionally demanding naphthyl biaryls for the development of new ligands for asymetric synthesis

Regioselective Synthesis of 2-Amino-isophthalonitriles through a Ring Transformation Strategy

An expeditious synthesis of several 2-amino-isophthalonitriles and their biaryl compounds is described and illustrated by carbanion-induced ring transformation of functionalized 2H-pyran-2-ones with malononitrile in excellent yields. The strength of the reaction lies in the creation of an aromatic ring at room temperature from six membered-lactones under mild reaction conditions. This approach is an alternative to Diels-Alder reactions of 2H-pyran-2-ones with dienophiles, which require forcing thermal conditions to obtain benzene derivatives.

Odorless Preparation Of Thioglycosides And Thio Michael Adducts Of Carbohydrate Derivatives

A generalized, odorless, one-pot methodology has been developed for the preparation of 1,2-trans-thioglycosides and thio-Michael addition products of carbohydrate derivatives through triphenyl phosphine mediated cleavage of disulfides and reaction of the thiolate formed in situ with glycosyl bromides and glycosyl conjugated alkenes.

Synthesis of a pentasaccharide repeating unit of the extracellular polysaccharide produced by lactobacillus delbrueckii subsp. Bulgaricus 291

A pentasaccharide as its methyl glycoside has been synthesized efficiently using a modified glycosylation strategy. This pentasaccharide is a repeating unit of the exopolysaccharides produced by Lactobacillus delbrueckii subsp. bulgaricus 291

Glycosylation and pyranose-furanose isomerization of carbohydrates using HClO4-SiO2: Synthesis of oligosaccharides containing galactofuranose

A series of di- and trisaccharides containing galactofuranose were synthesized using HClO4-SiO2 catalyzed glycosylation and ring transformation for the conversion of galactopyranose to galactofuranose. Yields in glycosylations and ring transformation reactions were excellent.

Concise synthesis of two trisaccharide analogs related to the glycone constituent of Phanoside, a novel insulin releasing natural product

Two trisaccharides (2 and 3) related to related to the glycone part of Phanoside, an insulin release stimulator have been synthesized in excellent yield.

Efficient Synthesis of Glycosyl Enaminoesters Directly from Glycosyl Azides

A convenient methodology has been developed for the synthesis of glycosylenaminoesters directly from glycosyl azides under hydrogenetion condition. Yields were moderate to good in all cases.

Aza-Michael addition of amines to activated alkenes catalyzed by Silica supported perchloric acid under a solvent-free condition

An efficient aza-Michael addition of amines to a series of ,-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.

Synthesis of oligosaccharides corresponding to the polysaccharides of Lactobacillus and Thermophlilus strains

Synthesis of a branched trisaccharide and a tetrasaccharide repeating units corresponding to the polysaccharides of Lactobacillus spp. G-77 and Thermus thermophilus Samu-SA1 as their methyl glycosides has been achieved in excellent yield. Most of the glycosyl linkages are 1,2-cis in these oligosaccharide fragments

Mild and efficient hydrolysis of thioglycosides to glycosyl hemiacetals using N-iodosaccharin

A convenient methodology has been developed for the mild hydrolysis of thioglycosides to the corresponding hemiacetals using N-iodosaccharin without any requirement of co-activator. Most of the functional groups used for the protecting group manipulation of carbohydrates are remain unaffected under the reaction condition.

Regioselective Synthesis of Functionally Crowded Benzenes at Room Temperature through Ring Transformation of 2H-Pyran-2-ones

An expeditious synthesis of highly substituted benzenes with electron withdrawing or donating substituents is described and illustrated by carbanion-induced ring transformation of 2H-pyran-2-one with malononitrile in excellent yield. The novelty of the reaction lies in the creation of an aromatic ring at room temperature from six membered-lactones under mild reaction conditions.

Reductase inhibitory activity of some flavones: Topological descriptors in modeling the activity

In healthy people, glucose is metabolized through Embden-Meyerhoff pathway. In cases of diabetes mellitus, with the increased levels of glucose in insulin-insensitive tissues the Aldose Reductase (AR) in polyol pathway facilitates the conversion of glucose to sorbitol. In this cascade of events the accumulated sorbitol is attributed to be responsible for cataract, neuropathy and retinopathy in diabetic cases.1,2 Thus, the inhibition of AR in polyol pathway may prevent and lead to the cure of the complications arising out of the diabetes mellitus. In this background, Matsuda and coworkers3 studied the AR inhibitory activity of large number of flavones and related compounds from traditional antidiabetic remedies. Here, many of these compounds shared 2-Aryl-benzpyran-4-one as scaffold for different chemical groups surrounding this moiety. This offers scope to investigate the AR inhibitory activity of these compounds in relation to the functional group environment surrounding this core

Topological Descriptors in Modeling the Antimalarial Activity of 4-(3’, 5’-Disubstitutedanilino)quinolines

Two series of closely related antimalarial agents, 7-chloro-4-(3’,5’-disubstitutedanilino) quinolines, have been analyzed using Combinatorial Protocol in Multiple Linear Regression (CP-MLR) for the structure-activity relations with more than 450 topological descriptors for each set. The study clearly suggested that 3’- and 5’- substituents of the anilino moiety map different domains in the activity space. While one domain favors the compact structural frames having aromatic, heterocyclic ring(s) substituted with closely spaced F, NO2 and O functional groups, the other prefers structural frames enriched with unsaturation, loops, branches, electronic content and devoid of carbonyl function. Also, this study gives an indication in favour of the electron rich centres in the aniline substituent groups for better antimalarial activity; an observation in line with several of the previous reports too. The models developed and the participating descriptors suggest that the substituent groups of the 4-anilino moiety of the 4-(3’, 5’-disubstitutedanilino)quinolines hold scope for further modification in the optimisation of the antimalarial activity.