Stereocontrolled photocyclization of 1,2-diketones: application of a 1,3-acetyl group transfer methodology to carbohydrates.
Photolysis of 1-glycosyl-2,3-butanodione derivatives using visible light is a mild and selective procedure for the synthesis of chiral 1-hydroxy-1-methyl-5-oxaspiro[3.5]nonan-2-one carbohydrate derivatives. The results strongly suggest that stereocontrol of the cyclization is dependent on conformational and stereoelectronic factors. Further oxidative opening of the 1-hydroxy-1-methyl-2-cyclobutanone moiety affords new C-ketoside derivatives either in C- and O-glycoside series. This tandem two-step process could be considered to be a stereocontrolled 1,3-transference of an acetyl group, and it can be applied either to pyranose and furanose models.
Herrera
Antonio J
AJ
Instituto de Productos Naturales y Agrobiología del C.S.I.C. Carretera de La Esperanza 3, Tenerife, Spain. esuarez@ipna.csic.es
Rondón
María
M
Suárez
Ernesto
E
D000107:Acetylation; D002241:Carbohydrates / Q000737:chemistry*; D003500:Cyclization; D007659:Ketones / Q000737:chemistry*; D008958:Models, Molecular; D015394:Molecular Structure; D010084:Oxidation-Reduction; D010777:Photochemistry; D013237:Stereoisomerism
D002241:Carbohydrates; D007659:Ketones