sentences:  In the development of MK-869, it was discovered that 3,5-disubstitution of the benzyl ring in the ether series gave greater potency than the 2-methoxy substitution in earlier benzylamine structures.It also was revealed that the TFMP group appeared to be especially important, and it is believed that it enhances activity in vivo and improves metabolism.Other groups, like the ortho-methoxyphenyl group, can be important in specific cases, but are thought to play a greater role in ligand preorganization through intramolecular hydrogen bonding, rather than through direct interaction with binding site residue.