Figure 2. Tuning reactivity of the sulfur electrophile.
SuTEx fragments were incubated with p-cresol in the presence of tetramethylguanidine (TMG, 1.1 equivalents) base and time-dependent covalent reaction monitored by the reduction of respective fragment starting material. Modifications to the adduct group (AG; A) and triazole leaving group (LG; B) could alter solution reactivity of SuTEx fragments. The calculated half-life of individual SuTEx fragments are shown in parentheses. The half-lives for all SuTEx fragments tested are listed in Table S1. Formation of the p-cresol adduct was confirmed by retention time that matched synthetic standards for respective reaction products (see Supporting Information for details of HPLC methods and data). Data shown are representative of n = 3 independent experiments.