Unexpected Cascade Sequence Forming the C(sp 3 )-N/C(sp 2 )-C(sp 2 ) Bond: Direct Access to γ-Lactam-Fused Pyridones with Anticancer Activity.

An unexpected Ugi cascade reaction was developed for the facile construction of γ-lactam-fused pyridone derivatives with high tolerance of substrates. A C(sp 3 )-N bond and a C(sp 2 )-C(sp 2 ) bond were formed together, accompanied by a chromone ring-opening in Ugi adducts, under the basic conditions without any metal catalyst for the whole process. Screening data of several difficult-to-inhibit cancer cell lines demonstrated that 7l displayed a high cytotoxicity against HCT116 cells (IC 50 = 5.59 ± 0.78 μM). Taken together, our findings revealed new insights into the molecular mechanisms underlying compound 7l and provided potential usage of this scaffold for cancer therapeutics.