A PROTAC molecule typically comprises a POI warhead, an E3 ligase recruiter, and a linker to connect both ligands. In contrast to tubastatin A, acknowledged for its enhanced selectivity toward HDAC10 relative to HDAC6 (8-fold), a bicyclic derivative featuring a dimethylamine moiety in the capping group demonstrated even greater selectivity, reaching up to 40-fold. Consequently, as shown in Figure , tubastatin A and its bicyclic derivative were utilized as warheads in the present study. The flexible alkyl chain, as a commonly reported linker type, was employed in the design. Furthermore, since the variation of the E3 ligase ligand has been shown to impact degrader activity as well as stability , two different CRBN ligands, specifically pomalidomide and a phenylglutarimide derivative, were chosen as E3 ligase recruiters. with hydrochloric acid to release the carboxylic acid group. The resulting compound was subjected to a HATU-mediated amide coupling reaction with O-benzylhydroxylamine hydrochloride to yield compound 3. Subsequently, the Boc-protecting group in compound 3 was removed with trifluoroacetic acid (TFA). The released secondary amine was then alkylated with tert-butyl (6-bromohexyl)carbamate to furnish compound 4 and 1-azido-6-bromohexane to generate compound 5.