2-Ethyl-3-[(R)-2-phenyl­butanamido]­quinazolin-4(3H)-one monohydrate

In the title compound, C₂₀H₂₁N₃O₂·H₂O (EQR·H₂O), the quinazoline ring system forms dihedral angles of 53.1 (1) and 85.6 (1)° with the phenyl ring and the amide link, respectively. In the crystal, O—H...O hydrogen bonds link two EQR and two water mol­ecules into a centrosymmetric R₄⁴(18) ring motif. N—H...O hydrogen bonds further link these hydrogen-bonded fragments into columns extending in [010].