“…Model experiments with anhydride 5 and amines 14, 16, 19, and 21 (see Experimental Section) showed the regioselective formation of the expected adducts, resulting from amine attack upon the more reactive electron-deficient C1-carbonyl. 18,19 How- ever, minor amounts of regioisomeric adducts arising from attack to the less reactive C4-carbonyl were also observed ( 1 H NMR and or HPLC analysis) under our optimized reaction conditions. 20 Libraries 1-5 were duplicated, and one set was submitted to acetate cleavage in the presence of NaOMe/MeOH, followed by quenching with excess Amberlyst15 as a proton source to give libraries 9-13.…”