Synthesis, regioselective hydrogenolysis, partial hydrogenation, and conformational study of dioxane and dioxolane-type (9′-anthracenyl)methylene acetals of sugars

Abstract

Dioxane-type (9'-anthracenyl)methylene acetal of methyl 2,3-di-O-methyl-alpha-D-glucopyranoside was cleaved with LiAlH(4)/AlCl(3) (3:1) or with Na(CN)BH(3)-HCl regioselectively to provide the 4- or 6-O-(9'-anthracenyl)methyl ether, respectively. Hydrogenolytic reaction of the exo and endo isomers of dioxolane-type acetals proved to be directed by the configuration of the acetalic carbon as well as by the intramolecular participation of the adjacent-free hydroxyl; ring-opening reaction of the endo isomer of the methyl 2,3-O-(9'-anthracenyl)methylene-alpha-L-rhamnopyranoside took place with complete selectivity resulting in the axial (9'-anthracenyl)methyl ether, whereas a 1:1 mixture of the axial and equatorial ethers was formed upon the same reaction of the exo isomer. Catalytic hydrogenation of the sugar acetals resulted in (9',10'-dihydro-9'-anthracenyl)methylene derivatives without affecting the acetalic center. High-temperature molecular dynamics simulations and DFT (Density Functional Theory) geometry optimizations were carried out to study the conformation of the dioxane-type (9',10'-dihydro-9'-anthracenyl)methylene acetal.

Synthesis of C‐2‐ and C‐3‐Sulfonatomethyl O‐ and S‐Glycosides by Horner–Wadsworth–Emmons Olefination

“…To gain an insight into the conformational preferences and relative energies of compounds 7a , 7b and 8 , high‐temperature molecular dynamics and DFT calculations were performed . B3LYP/6‐31G(d) re‐optimization of the clustered high‐temperature dynamics structures by neglecting the rotation of the Ph, SO 3 Et and OMe groups resulted in global minima, in agreement with the experimental findings.…”

“…Computational Section: The molecular dynamics simulations (500 ns, 1200 K constant temperature, 1 fs time step) and the preliminary geometry optimizations using the suitably developed GAFF empirical force field on the equidistantly saved 500000 trajectory snapshot geometries were carried out by means of the Amber molecular dynamics simulation package , . Distance‐based clustering of both the GAFF and the DFT‐optimized structures was performed for the heavy atoms of the sugar ring, the dioxane ring, the double bond and the first connecting heavy atoms by applying a 0.5 Å cut‐off with an in‐house code (written by A. Mándi).…”

Regioselective Ring Opening of 1,3‐Dioxane‐Type Acetals in Carbohydrates

“…The (9′‐anthracenyl)methylidene acetal was introduced in 2003 by Ellervik as a new protecting group, which contributes to the crystalline properties of the protected carbohydrates and exhibits strong absorbance and fluorescence . Analogous to the naphthyl derivatives, the (9′‐anthracenyl)methylidene acetal in 95 is partially reduced by LiAlH 4 ‐AlCl 3 to selectively yield the 4‐ O ‐(9′‐anthracenyl)methyl ether 96 (Scheme ) …”

Analysis of carbohydrates and glycoconjugates by matrix‐assisted laser desorption/ionization mass spectrometry: An update for 2009–2010

“…For development of fluorescence assay (Haga et al, 2009) Carbohydrate-functionalized salphen-metal complexes TOF Complexes with peripheral glucose and galactose substituents. Self-assembled supramolecular structures were produced (Hui et al, 2009) Dioxolane-type (9'anthracenyl)methylene acetals TOF Synthesis, regioselective hydrogenolysis, partial hydrogenation, conformational study (Jakab et al, 2009) measurement and structure, particularly when structures are selected directly from databases. At present, no one mass spectrometric technique can identify all structural features of carbohydrates.…”