We wish to propose a new structure (IV) for the alkaloid. In our view, the new formula is better in accord with the color of sempervirine, and with the formation from it of tetrahydroisoyobyrine. Beyond that we have been able to marshal new facts which provide further strong support for (IV). Thus,(i) the infrared spectrum of sempervirine contains no band in the NH region, while by contrast, all N-unsubstituted indole derivatives are ...
