Synthesis, structure and reactivity of 5-pyranosyl-1,3,4-oxathiazol-2-ones.
5-(1,2,3,4-tetra-O-acetyl-alpha-D-xylopyranos-5S-C-yl)-1,3,4-oxathiazol-2-one (8) has been prepared from glucuronamide in two steps and 73% overall yield by conversion to the tetra-O-acetyl derivative 7 followed by reaction with chlorocarbonylsulfenyl chloride. 5-(2,3,4-Tri-O-acetyl-beta-D-xylopyranosyl)-1,3,4-oxathiazol-2-one (12) was synthesised from D-xylose by a four-step sequence involving conversion to the xylopyranosylnitromethane derivative 9, reaction with PCl3 to afford nitrile 10, hydrolysis to amide 11, and finally treatment with ClCOSCl. D-glucose-derived analogue 13 was prepared similarly. The structure of oxathiazolone 8 was established by X-ray crystallography. Thermolysis of the oxathiazolones 8 and 12 at 130-160 degrees C resulted in decarboxylation and desulfuration to yield the corresponding nitriles. Attempts to trap the putative nitrile sulfide intermediates by repeating the thermolysis in the presence of dipolarophiles, such as ethyl cyanoformate, afforded only traces of the 1,3-dipolar cycloadducts; however, under microwave irradiation oxathiazolone 8 and ethyl cyanoformate afforded ethyl 3-(1,2,3,4-tetra-O-acetyl-alpha-D-xylopyranos-5S-C-yl)-1,2,4-thiadiazole-5-carboxylate 22 in good yield.
McMillan
Keith G
KG
EaStCHEM, School of Chemistry, The University of Edinburgh, The King's Buildings, West Mains Road, Edinburgh EH9 3JJ, UK.
Tackett
Miles N
MN
Dawson
Alice
A
Fordyce
Euan
E
Paton
R Michael
RM
D018360:Crystallography, X-Ray; D008872:Microwaves; D009570:Nitriles / Q000737:chemistry; D011714:Pyrans / Q000138:chemical synthesis* / Q000737:chemistry*; D013440:Sulfides / Q000737:chemistry; D013844:Thiazoles / Q000138:chemical synthesis* / Q000737:chemistry*
D009570:Nitriles; D011714:Pyrans; D013440:Sulfides; D013844:Thiazoles