Scheme 19. Summary of Yang's approach to the diversity-oriented synthesis of benzofurans and indoles. Reagents and conditions: (1) MeOH, 25 °C, 12 h; (2) xylene, 140 °C; (3) CH₂Cl₂–benzene (1 : 25), DDQ, (X = O, 87% over 3 steps; X = NMe, 61% over 3 steps).