Cyclic acetals of 4,1',6'-trichloro-4,1',6'-trideoxy-galacto-sucrose and their conversion into methyl ether derivatives

Synthesis and antitumor activity of lapathoside D and its analogs

Phenylpropanoid sucrose esters are important class of plant-derived natural products and have greater potential to be leads for new drugs because of their structural diversity and broad-array of pharmacological and biological activities. Regio- and chemo-selective acylation of 2,1':4,6-O-di-isopropylidene sucrose 4 with cinnamoyl chloride 5 and p-acetoxycinnamoyl chloride 6 afforded mono-, di-, tri- and tetra- variant PSEs in moderate yields. The first total synthesis of di-substituted PSE, lapathoside D 1' has been achieved successfully in short and simple synthetic steps from sucrose 3 as an inexpensive starting material. Lapathoside D 1 and a set of selected synthesized PSEs were tested for in vitro cytotoxicity against human cervical epithelioid carcinoma (HeLa) cell lines. Most of the compounds exhibited significant antitumor activity with their IC(50) values ranging from 0.05 to 7.63 μM. The primary screening results indicated that PSEs might be valuable source for new potent anticancer drug candidates.

Synthesis and ring-opening reactions of 4-chloro-4-deoxy-alpha-D-galactopyranosyl 3,4-anhydro-1,6-dichloro-1,6-dideoxy-beta-D-lyxo-hexulofuranoside

Treatment of 4-chloro-4-deoxy-alpha-D-galactopyranosyl 1,6-dichloro-1,6-dideoxy-beta-D-fructofuranoside (1) with 2.3 mol. equiv. of diethyl azodicarboxylate (DEAD) and 1.3 mol. equiv. of triphenylphosphine (TPP) in toluene gave a mixture of 3,6-anhydro-4-chloro-4-deoxy-alpha-D-galactopyranosyl 3,4-anhydro-1,6-dichloro-1,6-dideoxy-beta-D-lyxo-hexulofuranosi de (2, 55%) and 4-chloro-4-deoxy-alpha-D-galactopyranosyl 3,4-anhydro-1,6-dichloro-1,6-dideoxy-beta-D-lyxo-hexulofuranosi de (3, 35%). Compound 3 was also synthesised from 6-O-tert-butyldiphenylsilyl-4-chloro-4-deoxy-alpha-D-galactopyrano syl 1,6-dichloro-1,6-dideoxy-beta-D-fructofuranoside by epoxidation with DEAD-TPP and removal of the silyl ether group with tetrabutylammonium fluoride. The SN2 reactions of 2,3,6-tri-O-acetyl-4-chloro-4-deoxy-alpha-D-galactopyranosyl 3,4-anhydro-1,6-dichloro-1,6-dideoxy-beta-D-lyxo-hexulofuranosi de (5) with fluoride, chloride, bromide, iodide, and azide ions gave the corresponding 4'-derivatives 10, 12, 14, 18, and 20, respectively. Reduction of 4-chloro-4-deoxy-alpha-D-galactopyranosyl 4-bromo-1,6-dichloro-1,4,6-trideoxy-beta-D-fructofuranoside (15) gave 4-chloro-4-deoxy-alpha-D-galactopyranosyl 1,6-dichloro-1,4,6-trideoxy-beta-D-fructofuranoside (16). A similar reduction of 4-chloro-4-deoxy-alpha-D-galactopyranosyl 4-azido-1,6-dichloro-1,4,6-trideoxy-beta-D-fructofuranoside (21) gave 4-chloro-4-deoxy-alpha-D-galactopyranosyl 4-amino-1,6-dichloro-1,4,6-trideoxy-beta-D-fructofuranoside (22).