a Reagents and Conditions : a. 3–5 mol% PdCl2[P(o-tol)3]2, NaOt-Bu, Diglyme, reflux, 48h; b. POCl3, reflux, 2h; c. Piperazine, i-propanol, reflux, 4h; d. SnCl2,2H2O,ethanol,NaBH4, reflux 55 °C, 1.5h; e. bis-(2-chloroethyl)amine HCl, diglyme, K2CO3, reflux, 48h; f. Boc2O, EtOH; g. n-BuLi, trimethyl borate, −78 °C; h. 4-bromopyridine, Pd(PPh3)4, Na2CO3; i. TFA/CHCl3;