Synthesis and acetylcholinesterase/butyrylcholinesterase inhibition activity of 4-amino-2,3-diaryl- 5,6,7,8-tetrahydrofuro(and thieno)[2,3-b]-quinolines, and 4-amino-5,6,7,8,9-pentahydro-2,3-diphenylcyclohepta[e]furo(and thieno)-[2,3-b]pyridines

The acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) inhibition activities of a series of 4-amino-2,3-diaryl-5,6,7,8-tetrahydrofuro[2,3-b]quinolines (10-12)/4-amino-5,6,7,8-tetrahydro-2,3-diphenylthieno[2,3-b]quinoline (14) and 4- amino-5,6,7,8,9-pentahydro-2,3-diphenylcyclohepta[e]furo[2,3-b]pyridine (13)/4- amino-5,6,7,8,9-pentahydro-2,3-phenylcyclohepta[e]thieno[2,3-b]pyridine (15) are described. These compounds are tacrine (THA) analogues which have been prepared either from readily available 2-amino-3-cyano-4,5-diarylfurans (16-18) or from 2-amino-3-cyano-4,5-diphenylthiophene (19), via Friedländer condensation with cyclohexanone or cycloheptanone. These compounds are competitive inhibitors for acetylcholinesterase, the more potent being compound (13) which is threefold less active than tacrine. The butyrylcholinesterase inhibition activity is significant only in compounds 10 and 13, which are ten-fold less active than tacrine. It is found that the products 11 and 12 strongly inhibit acetylcholinesterase, and show excellent selectivity regarding butyrylcholinesterase.