1-Naphthyl Isothiocyanate → 1-(2-(2-tert-Butylphenoxy)pyridin-3-yl)-3-(naphthalen-1-yl)thiourea

A solution of 1b (40 mg, 0.17 mmol) and 1-naphtylisothiocyanate (34 mg, 0.18 mmol) in dioxane (2 mL) was heated at 60° C. for 6 h. More 1-naphtylisothiocyanate (34 mg, 0.18 mmol) was added and the mixture was heated at 60° C. for 8 days. The mixture was concentrated and the residue was purified by column chromatography on silica gel using a continuous gradient from 0% to 40% ethyl acetate in hexanes as eluent to afford 102a which was directly used in the next step. [M−H]−=426.18.