Synthesis of 6-O-Hexadecyl- and 6-O-Octylsucroses and Their Self-Assembling Properties Under Aqueous Conditions

This paper reports the synthesis and self-assembling properties of 6-O-hexadecyl- and 6-O-octylsucroses. Mono-etherification of 2,3,4,1′,3′,4′-hexa-O-benzylsucrose with the corresponding alkyl bromides predominantly took place at the glucose 6-position and the products were isolated by silica gel column chromatography. Benzyl groups in the isolated products were cleaved to yield the target derivatives. The SEM, TEM, XRD, and DLS results indicated that 6-O-alkylsucroses formed vesicle-type particles via formation of lamellar-like planes under aqueous conditions, which were further merged by fusion of the planes to construct larger aggregates. The self-assembling properties of the materials were different from those of the previously reported 6-O- and 6’-O-hexadecylsucroses mixture.     

Stereoselective synthesis of the beta-anomer of 4'-thionucleosides based on electrophilic glycosidation to 4-thiofuranoid glycals

Three types of 4-thiofuranoid glycal with different 3,5-O-silyl protecting groups were prepared and their electrophilic glycosidation was investigated. The 3,5-bis-O-(tert-butyldimethylsilyl)-4-thiofuranoid glycal (5) was obtained through mesylation of 2-deoxy-4-thio-D-erythro-pentofuranose (4) and subsequent base-promoted elimination, while thermal elimination of sulfoxide derivatives was suitable for the preparation of 3,5-O-(tetraisopropyldisiloxane-1,3-diyl) (9) and 3,5-O-(di-tert-butylsilylene) (11) 4-thioglycals. The glycosidation reactions of these 4-thioglycals were carried out, in the presence of either PhSeCl or NIS, by using silylated derivatives of uracil, thymine, cytosine, and N(6)-benzoyladenine. Among the three 4-thioglycals, 11 was found to be an excellent glycosyl donor, forming the desired beta-anomer exclusively irrespective of the nucleobase employed.