Tetrahydroquinazoline derivatives as selective cytotoxic agents

A compound of Formula I:

• or a pharmaceutically acceptable salt thereof, wherein:
• R1 is O or S;
• R2 is —H or —C1-8alkyl unsubstituted or substituted with 1 to 17 of F;
• R3 is halo or —C1-8alkyl unsubstituted or substituted with 1 to 17 of F;
• R4 is —H, halo, or —C1-8alkyl;
• R5 is —H or halo;
• R6 is —H or halo;
• and
• R7 is a 6-membered ring selected from
• (a) phenyl and
• (b) a heteroaryl of carbon atoms and 1, 2 or 3 nitrogen atoms, wherein one of the nitrogen atoms may optionally be in the form of an N-oxide, wherein the heteroaryl ring is attached by a carbon atom in the ring to the adjacent carbon atom in —C(R6)—;
• and
• wherein the 6-membered ring is unsubstituted or substituted with one or more substituents up to the maximum number allowed by valence, independently selected at each occurrence from:
• (i) halo, (ii) —CN, (iii) —NR8aR9a, (iv) —S(O)2NR8bR9b, (v) —C(O)NR8cR9c,
• (vi) —S(O)2C1-8alkyl, and (vii) oxo (═O),
• (viii) —C1-8alkyl unsubstituted or substituted with 1 to 8 substituents independently selected at each occurrence from —OH and halo,
• (ix) —O—(C1-8alkyl) unsubstituted or substituted with 1 to 8 substituents independently selected at each occurrence from —OH and halo, and
• (x) —C3-6cycloalkyl unsubstituted or substituted with 2 to 5 substituents independently selected at each occurrence from —OH and halo;
• and
• R8a, R8b, R8c, R9a, R9b and R9c are each independently selected at each occurrence from —H and —C1-8alkyl unsubstituted or substituted with 1 to 8 substituents independently selected at each occurrence from —OH and halo.