6,7,8,9-Tetrahydro-3-methyl-1H-pyrano[4,3-b]quinolin-1-one

The condensation reaction of 4-amino-6-methyl-2-pyrone with 1-cyclohexeneca rboxaldehyde and a catalytic amount of (S)-(+)-10-camphorsulfonic acid in t oluene at 358 K gave a 1:2.5 ratio of the title compound, (1) (C13H13NO2), and 7,8,9,10-tetrahydro-1H-pyrano[4,3-c]isoquinoline-l-one, (2). The format ion of (2) presumably proceeds through an intermediate imine. Both (1) and (2) show inhibitory activities against acetylcholinesterase and human aldos e reductase. Of the three linear-fused rings of(1), both ring A and ring B are planar and the angle between these planes is 0.46 (13)degrees. While th e two C atoms of cyclohexane ring C attached to its common atoms with ring B are in the plane of the latter, as expected, the remaining two C atoms of ring C are out of this plane, by 0.342 (4) and -0.402 (3) Angstrom, respec tively.