The structures of two antithrombotic quinazolone derivatives, etrahydr
o-2-benzylimidazo[5,1-b]-quinazolin-5-one, (I), and yl-2-[1-(2,5-xylid
ino)-ethyl]quinazolin-4(3H)-one, (II), display significant differences
in the bond lengths in one region of the quinazolone moiety.