Carbohydrate-urea-phenol-based adhesives: Transient formation of mono- and di-d-glucosylurea

Synthesis of novel N-acyl-β-d-glucopyranosylamines and ureas as potential lead cytostatic agents

Novel classes of acetylated and fully deprotected N-acyl-β-d-glucopyranosylamines and ureas have been synthesized and biologically evaluated. Acylation of the per-O-acetylated β-d-glucopyranosylurea (5), easily prepared via its corresponding phosphinimine derivative, by zinc chloride catalyzed reaction of the corresponding acyl chlorides RCOCl (a-f) gave the protected N-acyl-β-d-glucopyranosylureas (6a-f), in acceptable-to-moderate yields. Subsequent deacetylation of analogues 6a-f under Zemplén conditions afforded the fully deprotected derivatives 7a,b,d,e,f, while the desired urea 7c was formed after treatment of 6c with dibutyltin oxide. All protected and unprotected compounds were examined for their cytotoxic activity in different L1210, CEM and HeLa tumor cell lines and were also evaluated against a broad panel of DΝΑ and RNA viruses. Derivative 7c exhibited cytostatic activity against the three evaluated tumor cell lines (IC₅₀ 9-24 μΜ) and might be the basis for the synthesis of structure-related derivatives with improved cytostatic potential. Only analogue 6f weakly but significantly inhibited the replication of parainfluenza-3 virus, Sindbis virus and Coxsackie virus B4 in cell cultures at concentrations of 45-58 μM.

Crystal structure of 1-(2-amino-phen-yl)-3-phenyl-urea

In the title compound, C₁₃H₁₃N₃O, the phenyl ring makes a dihedral angle of 47.0 (1)° with the mean plane of the –NC(=O)N– unit, while the dihedral angle between the latter mean plane and the amino­phenyl ring is 84.43 (7)°. In the crystal, mol­ecules are linked via N—H⋯O hydrogen bonds involving the central –NHC(=O)NH– units, forming chains running parallel to the b axis. These chains associate with one another via N—H⋯O and N—H⋯N hydrogen bonds, from the pendant amino groups to the –NHC(=O)NH– units of adjacent mol­ecules, forming columns propagating along [010]. The structure was refined as a two-component twin with a 0.933 (3):0.067 (3) domain ratio.

Recent developments in glycosyl urea synthesis

The area of sugar urea derivatives has received considerable attention in recent years because of the unique structural properties and activities that these compounds display. The urea-linkage at the anomeric center is a robust alternative to the naturally occurring O- and N-glycosidic linkages of oligosaccharides and glycoconjugates, and the natural products that have been identified to contain these structures show remarkable biological activity. While methods for installing the β-urea-linkage at the anomeric center have been around for decades, the first synthesis of α-urea glycosides has been much more recent. In either case, the selective synthesis of glycosyl ureas can be quite challenging, and a mixture of α- and β-isomers will often result. This paper will provide a comprehensive review of the synthetic approaches to α- and β-urea glycosides and examine the structure and activity of the natural products and their analogues that have been identified to contain them.