A new bio-compatible pH cleavable linker for solid-phase synthesis of a squalamine analogue

Linkers that can be cleaved directly within the biological assay offer some advantages over traditional linkers in the range of direct screening applications that the associated libraries can be utilised for. The 1,6-elimination process is an efficient method of cleaving compounds from substituted 4-hydroxymethyl phenols, although giving rise to quinone methide by-products. Here, we report on a linker that uses an in-built amine ‘activator’ to cleave a phenoxy ester and hence to activate the linker to 1,6-elimination. An analogue of the antibacterial agent squalamine was synthesised and released using this linker strategy.