Foxy: 3-indoleacetic acid will not react with dialkylamines without further activation (e.g. with carbodiimides or as an acid chloride or anhydride).
Pure NaBH
4 wouldn't work for reduction of amides. NaBH
4 + activator (e.g. Lewis acids) will reduce amides, but will probably also reduce the indole to indoline (2,3-dihydroindole), at least to some extent. The same is true for borane BH
3.
Terbium: Lithium (as well as sodium) in liquid ammonia is a strong base and will only reversibly deprotonate the indole (and maybe the alpha-CH
2).
So LiAlH
4 is the reagent of choice for amide reduction in this case. I'm not aware of other (practical) routes. Maybe there are some obscure bath tub methods...