Serotonin 5-HT4 Receptor Agonistic Activity of the Optical Isomers of (±)-4-Amino-N-[2-(1-azabicyclo[3.3.0]octan-5-yl)ethyl]-5-chloro-2, 3-dihydro-2-methylbenzo[b]furan-7-carboxamide

The enantiomers, (R)-(-)-1 and (S)-(+)-1, of (±)-4-amino-N-[2-(1-azabicyclo[3.3.0]octan-5-yl)ethyl]-5-chloro-2, 3-dihydro-2-methylbenzo[b]furan-7-carboxamide [(±)-1] were prepared from optically active benzyl 4-acetylamino-2, 3-dihydro-2-methylbenzo[b]furan-7-carboxylate[(R)-(+)-6, (S)-(-)-6], respectively. The requisite (R)-(+)-6 and (S)-(-)-6 were prepared by large-scale preparative HPLC on chiral stationary phases (CSPs). The absolute configuration of (S)-(+)-1 was determined by single crystal X-ray analysis. The serotonin 5-HT4 receptor agonistic activity of (S)-(-)-1 hemifumarate (SK-951) which was hemifumarate of (S)-(+)-1 was about twice that of the other enantiomer (R)-(+)-1 hemifumarate which was hemifumarate of (R)-(-)-1.