The three covalent analogs of varying reactivity were synthesised from a common intermediate, the Boc-amine protected methyl ester 10 (Scheme S1). Compound 10 was obtained from a fivestep synthesis based on that of the hit compound TCMDC-135051 (1). After global deprotection of 10, warheads were coupled onto the piperazine linker using standard amide coupling conditions (Scheme S2). This yielded three molecules with presumed varying reactivity, as well as a non-covalent control analogue 12 with the non-electrophilic acetyl cap on the piperazine linker.