Electrochemical oxidative site-selective direct C-H activation of tanshinone IIA.

Natural products play a pivotal role in the advancement of state-of-the-art pharmaceuticals. To augment their therapeutic efficacy, structural modifications of these compounds are routinely performed. In this study, we introduce an efficient and environmentally benign electrochemical oxidative method for site-selective direct C-H activation of tanshinone IIA under metal-free, oxidant-free, and base-free conditions. Moderate to excellent yields up to 92% of the desired tanshinone IIA derivatives were obtained with a broad substrate scope. Biological activity assays demonstrate that compounds 2k, 2q and 2w possess superior antitumor efficacy compared to tanshinone IIA.