Convergent Synthesis of 4-Thiomaltooligosaccharides

Abstract

Methyl 4,4^II,4^III-trithio-α-maltotetraoside (2) and its pentasaccharide homologue 3 were conveniently synthesized by treatment of methyl 4^II-O-triflyl-4-thiomaltoside derivative 10 with the respective peracetylated 1,4-dithio- and 1,4,4^II-trithio-maltooligosaccharides 16 and 18, in the presence of diethylamine

Key words

carbohydrates - α-amylase - inhibitor - S-glycosides

References

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9

General Procedure for Coupling Reactions. To a solution in DMF (1 mL) of freshly prepared triflate (0.04 mmol) was added 1,4-dithioerytritol (0.04 mmol), the acceptor (0.05 mmol) and at 0 °C diethylamine (0.08 mmol). After stirring for 40-60 min at r.t., DMF was removed and the residue was diluted in CH₂Cl₂, washed with water and purified by flash chromatography.

10

Selected physical and spectroscopic data for key compounds. Ascending order of roman numerals were assigned to the residues starting from the reducing end. Compound 9: [α]_D ²⁰ = +123 (c = 1.6, CHCl₃). ¹³C NMR (75 MHz, CDCl₃): δ = 97.1 (C-1^I), 84.7 (C-1^II), 55.5 (CH₃), 45.5 (C-4^I). Compound 16: [α]_D ²⁰ = +261 (c = 2.6, CHCl₃). ¹³C NMR (75 MHz, CDCl₃): δ = 82.3 (C-1^II), 80.1 (C-1^I), 43.3 (C-4^I). Compound 18: [α]_D ²⁰ = +268 (c = 1.8, CHCl₃). ¹³C NMR (75 MHz, CDCl₃): δ = 82.3, 82.4 (C-1^II, 1^III), 80.1 (C-1^I), 43.6 (C-4^I, 4^II). Compound 19: [α]_D ²⁰ = +237 (c = 6.2, CHCl₃). ¹³C NMR (75 MHz, CDCl₃): δ = 97.0 (C-1^I), 82.6, 83.3, 83.5 (C-1^II, 1^III, 1^IV), 55.4 (CH₃), 43.6, 45.5, 45.6 (C-4^I, 4^II, 4^III). Compound 20: [α]_D ²⁰ = +258 (c = 1.1, CHCl₃). ¹³C NMR (75 MHz, CDCl₃): δ = 97.0 (C-1^I), 82.5, 82.6, 83.3, 83.5 (C-1^II, 1^III, 1^IV, 1^V), 55.4 (CH₃), 43.6,43.9, 45.5, 45.6 (C-4^I, 4^II, 4^III, 4^IV). Compound 2: ¹³C NMR (75 MHz, D₂O): δ = 99.7 (C-1^I), 85.9 (C-1^II, 1^III, 1^IV), 55.4 (CH₃), 47.0 (C-4^I, 4^II, 4^III). Compound 3: ¹³C NMR (75 MHz, D₂O): δ = 99.7 (C-1^I), 86.0, 86.1 (C-1^II, 1^III, 1^IV, 1^V), 55.4 (CH₃), 47.0 (C-4^I, 4^II, 4^III, 4^IV).