.delta.-Valerolactone .delta.-Valeryllactone .gamma.-Valerolactone 2H-Pyran-2-one, tetrahydro- 5-Valerolactone 542-28-9 NSC6247 Pentanoic acid, 5-hydroxy-, .delta.-lactone Tetrahydro-2-pyranone Valeric acid, .delta.-hydroxy-, .delta.-lactone WLN: T6OVTJ