3-(R)-3-(2, 3-Dihydrobenzofuran-5-yl)-1, 2, 3, 4-tetrahydropyrrolo [3, 4-b] quinolin-9-one (1) is a key intermediate in the synthesis of pyrroloquinolone analogues, a series of highly potent and selective phosphodiesterase 5 (PDE5) inhibitors. Racemic 1-(2, 3- dihydrobenzofuran-5-yl)-2, 3, 4, 9-tetrahydro-1 H-β-carboline (6, Scheme 2) was prepared by Pictet-Spenger condensation in 84% isolated yield with> 97% chemical purity. The ...