Scheme 4.

Synthetic Route to Pyrrolyl DKAs 6k,l and 7k,l^a

^aReagents and conditions: (i) NIS, acetone, −78 °C, 96 h; (ii) phenylboronic acid, Cs₂CO₃, P(t-But)₃, Pd₂(dba)₃, dioxane, 80 °C, 24 h; (iii) diethyl oxalate, C₂H₅ONa, THF, room temp, 2 h; (iv) 1-trityl-1H-[1,2,4]triazole-3-carboxylic acid ethyl ester,³⁶ n-BuLi, THF, from −78 to 0 °C, 3.5 h; (v) 3 M HCl sol, 1,4-dioxane, 60 °C, 30 min; (vi) 1 N NaOH, THF/CH₃OH, room temp, 1 h.