Scheme 5. Ring-expansion of substituted tetrahydroquinolines. Conditions: a (1) KHMDS (2 equiv.), THF, 0 °C, 1–1.5 h; (2). MeOH; b 2 M HCl : MeOH (1 : 1), reflux, 44 h. c (1) KHMDS (4 equiv.), THF, 0 °C, 5 h. (2) MeOH. CCDC deposition numbers for X-day data: 161993733; 18a1993734.†.