Alstoscholarisines H–J, Indole Alkaloids from Alstonia scholaris: Structural Evaluation and Bioinspired Synthesis of Alstoscholarisine H

Alstoscholarisines H–J (1–3), new monoterpenoid indole alkaloids with an unprecedented skeleton created via the formation of a C-3/N-1 bond, were isolated from Alstonia scholaris. Their structures were established by extensive spectroscopic analyses and the assessment of single-crystal X-ray diffraction data. The total synthesis of alstoscholarisine H was achieved via the regioselective nucleophilic addition of pyridinium through a bioinspired iminium ion intermediate followed by Pictet–Spengler-like cyclization.