(±)-3-(2-Aminopropyl)-7-benzyloxyindole 1, assembled from 7-benzyloxyindole 3 in 59% overall yield, is resolved with O, O′-di-p-toluoyl l-(2R, 3R)-tartaric acid 7 into (R)-1, a key intermediate of AJ-9677 2 (selective adrenaline β3-agonist) in 99.5% ee and 36% overall yield. The unwanted enantiomer (S)-1 (61.9% ee; recovered in 57% yield from the crystallization filtrate) can be reused in another round of resolution after its enantiomeric ...
