1. It is possible that the accepted structure for cryptolepine was actually isolated 45 years after its initial synthesis by Fichter and Boehringer. Clinquart isolated a purple compound in 1929 (mp 160 °C), assumed to possess a primary NH2group, from the roots ofC. triangularisN. E. Br. collected in Kisantu (Belgian Congo). He named this compound cryptolepine and proposed the formula C14H17N2O4(see ref 2). Delvaux isolated a purple base in 1931 (mp 193−194 °C) from the same plant material which he named cryptolepine and proposed the formula C17H16N2O (see refs 4 and 5). The accepted formula for cryptolepine, C16H12N2, was first isolated as a purple solid (mp 175−178 °C) by Gellért in 1951 fromC. sanguinolenta(see ref 6). Gellért assigned the structure of
2. (1) to cryptolepine. The structure of cryptolepine was recently verified by NMR spectroscopy in 1991 by Tackie et al. (see ref 7) and by unambiguous synthesis in 1998 by Bierer et al. (see ref 8).