Scheme 1.
Synthesis scheme for derivatisation of PL to type A, B and C ABPP probes. (Type A) PL hydrochloride is protected with a methoxymethyl (MOM) group and as a methyl acetal, which is then alkylated at the C2′ position as described previously.[ 13 , 20 ] The compound is further modified with an azide linker. Final deprotection leads to type A probes. (Type B) PL hydrochloride is protected to the pivaloyl (Piv) ester, oxidized to the N‐oxide with meta‐chloroperbenzoic acid (m‐CPBA), activated by iso‐butyl chloroformate (IBCF) and then reacted with an alkyne‐Grignard reagent to form C6 modified PL scaffolds. [21] Final, basic deprotection leads to type B derivatives. (Type C) Deprotonation of PL hydrochloride at the C3 alcohol and substitution with propargyl bromide yields type C probe PL13. [22]