Here is the main song, Pure imagination, from the most famous movie "Willy Wonka & the Chocolate Factory" (1971), performed by several stars.
By Gene Wilder (in the movie)
By Lou Rawls (1976)
By Roslyn Kind (Barbra Streisand's sister) (2008) (medley with You and I)
By Barbra Streisand (23/08/2016)