One-Pot Total Synthesis of Natural Products Nitramarine, Nitraridine, and Analogues via a Cascade Oxidation/Pictet–Spengler Condensation/Annulation Process

A cascade oxidation/Pictet–Spengler condensation/annulation process has been developed for the one-pot total synthesis of nitramarine, nitraridine, and their analogues. The procedure proceeded with easily available quinolines and tryptophan derivatives. A simple and metal-free approach, wide substrate scope, and functional group tolerance make it applicable for the synthesis of diverse bioactive nitramarine, nitraridine, and their derivatives. Furthermore, the bioactivity evaluation has identified two promising leading compounds 5d and 5e with potent antitumor proliferative activity against breast cancer cells.