Figure 5
General synthetic procedure followed for the preparation of 23a-c, 24a-d, 25a-d. (i) Na2CO3, Pd(PPh3)2, THF/H2O, r.t. 8 h, 60 °C 12 h; (ii) β-alanine, AcOH, 100 °C 1 h; (iii) K2CO3, DMF, r.t. o.n., 60 °C 72 h; (iv) secondary amine, DIPEA, DCM, 0 °C to r.t. 20 min.
