A simple and convenient synthetic protocol for O-isopropylidenation of sugars using bromodimethylsulfonium bromide (BDMS) as a catalyst

Silicomolybdic Acid Cluster as Biocompatible Catalyst for One-Pot Tandem Synthesis of Orthogonally Protected Glycosides

The present paper describes a new and practical approach for the one-pot preparation of O-isopropylidene derivatives and also orthogonally protected S- and O-glycosides from the corresponding unprotected saccharides by employing 2 mol % of a silicomolybdic acid (SMA) cluster as a versatile and biocompatible catalyst. The present protocol is applicable to two-step one-pot tandem transformations, which include the O-isopropylidation, spiroketal functionalization, 4,6-O-arylidene acetalations, and arylidene acetylation processes under relatively mild reaction conditions. One-pot sequential transformations, low catalyst loading, rapid transformation, high to excellent reaction yields, mild reaction conditions, and a nontoxic biocompatible workup procedure are the notable advantages of devised protocol.

A mild deprotection of isopropylidene ketals from 2-deoxyglycosides using AcOH/H2O/DME: An efficient regioselective deprotection of terminal isopropylidene ketals

This paper describes a mild and efficient catalytic deprotection method for isopropylidene ketals and benzylidene acetals using AcOH/H2O/DME(1,2-Dimethoxyethane). The method effectively removes ketal and acetal protecting groups from 2-deoxyglycosides which are prone to hydrolysis under acidic conditions. Moreover, it enables the selective removal of the terminal ketal over an internal one.

Synthesis and in vitro Bioactivity Evaluation of New Galactose and Fructose Ester Derivatives of 5-Aminosalicylic Acid

Inflammatory bowel disease (IBD) is the main risk factor for developing colorectal cancer which is common in patients of all ages. 5-Aminosalicylic acid (5-ASA), structurally related to the salicylates, is highly active in the treatment of IBD with minor side effects. In this study, the synthesis of galactose and fructose esters of 5-ASA was planned to evaluate the role of glycoconjugation on the bioactivity of the parent drug. The antibacterial activity of the new compounds were evaluated against two Gram-negative and two Gram-positive species of bacteria, with a notable effect observed against Staphylococcus aureus and Escherichia coli in comparisons with the 5-ASA. Cytotoxicity testing over HT-29 and 3T3 cell lines indicated that the toxicity of the new products against normal cells was significantly reduced compared with the original drug, whereas their activity against cancerous cells was slightly decreased. The anti-inflammatory activity test in RAW264.7 macrophage cells indicated that the inhibition of nitric oxide by both of the monosaccharide conjugated derivatives was slightly improved in comparison with the non-conjugated drug.

Use of Bromine and Bromo-Organic Compounds in Organic Synthesis

Bromination is one of the most important transformations in organic synthesis and can be carried out using bromine and many other bromo compounds. Use of molecular bromine in organic synthesis is well-known. However, due to the hazardous nature of bromine, enormous growth has been witnessed in the past several decades for the development of solid bromine carriers. This review outlines the use of bromine and different bromo-organic compounds in organic synthesis. The applications of bromine, a total of 107 bromo-organic compounds, 11 other brominating agents, and a few natural bromine sources were incorporated. The scope of these reagents for various organic transformations such as bromination, cohalogenation, oxidation, cyclization, ring-opening reactions, substitution, rearrangement, hydrolysis, catalysis, etc. has been described briefly to highlight important aspects of the bromo-organic compounds in organic synthesis.

Alternative synthesis and antibacterial evaluation of 1,5-dideoxy-1,5-imino-L-rhamnitol

A convenient synthesis is described of 5-azido-5-deoxy-2,3-O-isopropylidene-L-rhamnofuranose from L-rhamnose in seven steps and 17% overall yield. A key feature of the synthesis is the selective oxidation of the secondary alcohol in 2,3-O-isopropylidene-L-rhamnofuranose in the presence of the hemiacetal to give the corresponding ketone in good yield using the Parikh-Doering reagent. 5-Azido-5-deoxy-2,3-O-isopropylidene-l-rhamnofuranose is then converted by a literature protocol to 1,5-dideoxy-1,5-imino-L-rhamnitol, which was found to have no significant antimicrobial activity against Pseudomonas aeruginosa, methicillin-resistant Staphylococcus aureus, and Escherichia coli.

Synthesis and in vitro bioactivity evaluation of new glucose and xylitol ester derivatives of 5-aminosalicylic acid

Synthesis,in vitroanti-bacterial, anti-inflammatory and anti-cancer activity evaluations andin silicostudy of monosaccharide derivatives of mesalazine in comparison with parent drug.

Organoiridium complexes: efficient catalysts for the formation of sugar acetals and ketals

[Cp(∗)IrCl(2)](2) is used as an efficient promoter for the synthesis of sugar acetals and ketals with good to excellent yields. The catalyst is found to be general for a wide range of sugars.

Acetonation of L-pentoses and 6-deoxy-L-hexoses under kinetic control using heterogeneous acid catalysts

The fibrous polymer-supported sulfonic acid catalyst Smopex-101 H+ proved to be an efficient catalyst for the preparation of O-isopropylidene derivatives from a series of rare sugars. Acetonation of the reducing sugars L-arabinose, L-ribose, L-xylose, L-fucose, and L-rhamnose in N,N-dimethylformamide by 2,2-dimethoxypropane or 2-methoxypropene led to the formation of the kinetically favored di-O- and/or mono-O-isopropylidene derivatives in 46-88% yields. The method consists of a simple experimental procedure which does not require predried solvents or reagents. The catalyst is easily recovered and can be regenerated making the procedure economically viable even for large-scale synthesis.