Carotinoid-Glycosylester. 3. Mitteilung. Die synthese von crocetin-di-(β-D-glucosyl)-ester. Eine neue methode zur selektiven veresterung von ungeschützter β-D-glucose

Carotenoid Glycosyl Esters. The Synthesis of Crocetin-di-(β-D -glucosyl) Ester. A New Method for the Selective Esterification of Unprotected β-D -Glucose The naturally occurring crocetin-di-(β-D -glucosyl) ester is easily synthesized by the reaction of crocetin-di-imidazolide or crocetin-di-(1,2,4-triazolide) and unprotected β-D -glucose in pyridine in presence of a base (Scheme 4). Under the described experimental conditions the esterification takes place exclusively at the anomeric C-atom and furthermore produces only the β-anomer. It is the first time that an unprotected carbohydrate has been used for the selective synthesis of glucosyl esters at the anomeric C-atom. This represents the major advantage of this new method.