Comment on Enantioselective Total Synthesis of (−)-Colchicine, (+)-Demecolcinone and Metacolchicine: Determination of the Absolute Configurations of the Latter Two Alkaloids by B. Chen, X. Liu, Y.-J. Hu, D.-M. Zhang, L. Deng, J. Lu, L. Min, W.-C. Ye and C.-C. Li, Chem. Sci., 2017, 8, 4961–4966