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

Abstract

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.