The synthesis and enantiomeric features of 2-hydroxymethyl-tetrahydro-oxazolo[3,2-c]pyrimidine-5,7-(4H,6H)-diones (V) are. described. The diazomethane methylation of these bicyclic compounds afforded 2-hydroxymethyl-6-methyl-tetrahydro-oxazolo-[3,2-c]pyrimidine-5,7-(4H,6H)-diones (R)-(XXII) and (S)-(XXII), respectively. For the synthesis of (R)-V and (S)-V the respective 5-bromo-1-(2,3-dihydrox...

The aromaticity of some bicyclic heterocycles is discussed with the aid of the configuration analysis of the expansion coefficient matrices and the similarity analysis of the density matrices. The iso-it-electronic [9] annulenyl anion is taken as the aromatic reference compound for all the heterocyclic compounds considered. The restflts are compared with · those previously obtained from conside...

Let ∆(G), ∆ for short, be the maximum degree of a graph G. In this paper, trees (resp., unicyclic graphs and bicyclic graphs), which attain the first and the second largest spectral radius with respect to the adjacency matrix in the class of trees (resp., unicyclic graphs and bicyclic graphs) with n vertices and the maximum degree ∆, where ∆ ≥ n+1 2 (resp., ∆ ≥ n 2 +1 and ∆ ≥ n+3 2 ) are determ...

The uptakes of cycloalkanes (C5 - C8) and bicyclic aromatic compounds (naphthalene, biphenyl, and azulene) by both strong acid cation (Dowex 50W-X4 and X8) and strong base anion (Dowex 1-X4 and X8) exchange resins have been studied in aqueous solutions at 25 degrees C; their distribution constants (K) have been determined. The relationship between the octanol-water partition coefficient and the...

Synthesis of β-C-D-galactosyl D- and L-alanines is carried out via a highly stereoselective Grignard reaction of glycosyl iodides, Sharpless dihydroxylation and S(N)2 displacement of the corresponding mesylate or tosylate. Alternatively, attempted triflation of the intermediate alcohols triggers a stereoselective debenzylative cyclization leading to interesting bicyclic trans-fused compounds.

Electrophilic ring opening of spiro-cyclopropanecarboxylated sugars followed by reaction with DBU revealed interesting ring-contraction and ring-expansion reactions depending on the substrate and the kind of hydroxyl protective group present adjacent to the spiro center. A stereoselective method for accessing a new class of carbon chain extended keto-furanoses and C-glycosylated bicyclic compou...