The unsuccessful future-book favorites for the last two Kentucky Derbies met at Belmont Park today, seeking redemption.

One of them, Copelan, only sank further into obscurity. But the other, Deputy Minister, established himself as one of the East's top horses with his 4 3/4-length triumph over Fit To Fight in the $75,000-added Tom Fool Stakes.

Deputy Minister had been the 2-year-old champion of 1981, but suffered an injury that knocked him out of all the 3-year-old classics. This winter he launched a comeback by winning two stakes in Florida but was sidelined again.

Today he began a campaign that trainer Reynaldo Nobles hopes could bring him a championship at the end of the season, and he could not have started it better. After the favored Copelan and other speedsters in the field had battled for the lead, Deputy Minister swooped outside all of them on the turn and drew away.

Copelan finished sixth--his second straight poor finish since returning to competition after a series of dismal performances this spring.

Deputy Minister covered seven furlongs in a swift 1:22 1/5. "He is a super horse who is capable of big things," said Nobles, who indicated that the 4-year-old would start next in the Whitney Stakes at Saratoga.