General procedures for synthesis of a library of CBXs. Reaction
conditions: (a) corresponding ortho-substituted aniline
(−NH2, −NHMe, −OH, and −SH),
Appel’s salt (4,5-dichloro-1,2,3-dithiazolium chloride), pyridine,
70 °C, 16 h; (b) MeI, K2CO3, MeCN, rt,
72 h; (c) 1. corresponding 2-bromoaniline, Appel’s salt (4,5-dichloro-1,2,3-dithiazolium
chloride), pyridine, dry DCM, rt, 2 h; 2. CuI, dry pyridine, MWI,
115 °C, 20 min; (d) NaCN, DABCO, MeCN/H2O, rt, 7–24
h (for 83: KCN, DABCO, dry DMF, 100 °C, 48 h); (e)
Al, I2, dry MeCN, 80 °C, 18 h; (f) AlCl3, dry DCM, 40 °C, 18 h (for 41: Al, I2, dry MeCN, 80 °C, 18 h); (g) Fe, AcOH, rt, 2 h.