Design, synthesis and preliminary bio-evaluation of glucose–cholesterol derivatives as ligands for brain targeting liposomes

A series of glucose–cholesterol derivatives 8a–8e as ligands for brain targeting liposomes were synthesized. The preparation of compound 6 involved temporary protection of glucose with chlorotrimethylsilicane and hexamethyldisilazane followed by selectively hydrolyzed. The known cholesteryl tosylate 1 were coupled to ethylene glycols to afford alcohol 2a–2e. Substitution and deprotection of alcohol 2a–2e furnished the acids 4a–4e, which was condensed with compound 6 to get compounds 7a–7e, and then was deprotected in tetrahydrofuran with TFA to obtain the title compounds. As a model drug, tegafur was entrapped by liposomes coupled with 8b, and preliminary in vivo evaluation shown 8b could enhance the ability of liposomes delivering tegafur across the blood brain barrier.