I 14, R CH3 RI 16. R SH 16, R 'C7H7SOz 17, R= C7H7S0z8 R'* CH 2 W 18, R i C7H7S02, R '. CHO 19, RSH, R'= CHO 20, R= t. BuPhzSI. R'= CHO 21, RI-BuPhzSI. R 'a CH20H 22, Rst- BuPhnS~, R'= CH200CNHCH3 5, RaH, R'= CH200CNHCH3 panied by a small amount of the easily separable disubstituted compound 11. Cyclization with either H2S04 or polyphosphoric acid (PPA) was unsuccessful, but treatment of 10 with CF3S03H afforded ...