3-Indolebutyric acid (I) was activated as the hydroxamate (II) by coupling with N,O-dimethylhydroxylamine in the presence of EDC and DMAP. Addition of cyclopentenylmagnesium bromide (III) to hydroxamate (II) furnished the unsaturated ketone (IV). Then, Michael addition of coenzyme A (V) to the unsaturated ketone (IV) in the presence of triethylammonium bicarbonate buffer provided the desired adduct.