Carbohydrate‐Scaffolded Thymine Multimers: Scope and Limitations of the Allylation–Hydroboration Sequence

Abstract

Carbohydrates serve as versatile molecular scaffolds and platforms in organic chemistry, for example in combinatorial chemistry or for the multivalent presentation of ligands. Carbohydrate scaffolds are frequently employed in the synthesis of multivalent glycoconjugates and utilized for the study of fundamental parameters of carbohydrate recognition. However, facile procedures are required to achieve a useful variety of sugar platforms. Here, we report on the synthesis of a series of divalent und tetravalent hydroxypropylated mannosides, using an allylation‐hydroboration sequence. The hydroxypropyl‐linkers were further functionalized with thymine in a Mitsunobu reaction to achieve multivalent glycothymine scaffolds for intramolecular [2+2] photocyclization. This will be of importance to further investigate the influence of the 3D orientation in carbohydrate recognition. We discuss the scope of the allylation‐hydroboration sequence comparing 2,3‐, 2,6‐, and 4,6‐difunctionalization and 2,3,4,6‐tetrafunctionalization of protected 2‐aminoethyl α‐d‐mannopyranosides.