7-(Boc-leucinyl)aminonaphtho[2,1-d]thiazole-2-carbonitrile (69 mg, 0.16 mmol) was combined with 0.5 mL of thioanisole and 1.5 mL of DCM and stirred in an ice bath. Trifluoroacetic acid (1.5 mL) was added, and the reaction monitored by HPLC. After 1 h, solvents were removed under reduced pressure, and the remaining residue triturated with ether. The resulting solid was taken up in MeCN/H2O and treated with D-cysteine hydrochloride hydrate (55 mg, 0.31 mmol) and potassium carbonate (55 mg, 0.40 mmol). After 20 min, the reaction was filtered and the product was isolated by preparative HPLC eluting with 2→50% MeCN in 0.1% formic acid. Calcd for C21H23N4O3S2 (M+H): 443.1. found 443.
