Glycosidation, X. Synthesis of glycoconjugates of acetal‐glycosides with lysine and tripeptides for selective cancer therapy

Acetal‐glycosides 6 of cytotoxic aldehydes are a new class of compounds which may be of interest for cancer therapy, because of the possibility of a selective release of the cytotoxic principle in the tumour. For a selective transport to the tumour, these compounds will be connected to monoclonal antibodies, which bond specifically to tumour‐associated surface antigens. – In this paper the synthesis of acetal‐glycosides 14a–d and 15a–d with a COOH‐functionalised spacer and their connection to a lysine derivative 13 and a tripeptide 25 is described. The synthesis of 14a–d and 15a–d was performed by reaction of the acetals 7a–d and 8a–d with trimethylsilyl 2,3,4,6‐tetra‐O‐acetyl‐β‐D‐glucopyranoside (1) in the presence of a catalytic amount of trimethylsilyl trifluoromethanesulfonate to 9a–d and 10a–d followed by solvolysis and hydrolysis. The connection of 14a–d and 15a–d with 13 and of 14b,d with 25 to the glycoconjugates 20a–d, 21a–d, and 26a–b, respectively, was carried out with hydroxybenzotriazol via the activated esters 18 and 19.