We report on the first observation of D-1(0)(2420)-> D(0)pi(-)pi(+) and D-1(+)(2420)-> D(+)pi(-)pi(+) decays (where the contribution from the dominant known D-1-> D(*)pi decay mode is excluded) in the B--> D(1)(0)pi(-) and (B) over bar (0)-> D(1)(+)pi(-)