Remarkable effect of water in a regioselective lithiation of 5-(tert-butoxycarbonyl)-7-methoxy-1-methyl-1,3,4,5-tetrahydropyrrolo[4,3,2-de]quinoline

5-(tert-Butoxycarbonyl)-7-methoxy-1-methyl-1,3,4,5-tetrahydropyrrolo[4,3,2-de]quinoline (1b) was lithiated regioselectively at C-6 with sec-BuLi (3.0 equiv.) in the presence of water (1.0 equiv.) in ether at −78°C. Under conventional conditions, 1b was lithiated non-regioselectively at the C-6, C-8 and C-2 positions.