Core: a pyrimidine ring (six-membered aromatic ring with two nitrogens in a meta, 1/3 arrangement).
Number the ring with N at positions 1 and 3, then C2, C4, C5, C6.

1. Position 2: attached to a secondary amine that is bonded to the second carbon of a fully saturated five-carbon chain; as given: -NH-CH(CH3)-CH2-CH2-CH3.

2. Position 4: bonded to an sp2 carbon that further
   a) double-bonds to another carbon, and
   b) single-bonds to a cyclohexane ring (six-membered, fully saturated), with the carbon opposite (para to) the attachment point on the cyclohexane bearing a hydroxyl group (-OH).

3. Position 5: carries a side chain consisting of
   a) a carbonyl linkage (-C(=O)-), then
   b) a tertiary nitrogen (bearing one methyl group), then
   c) an ethylene spacer (-CH2-CH2-), and
   d) a second tertiary nitrogen bearing two methyl groups.

No other substituents are present on the pyrimidine core.