The pyrrolo[2,1-a]isoquinoline alkaloids.

The present chapter describes isolation, biogenetic proposals, and syntheses of the natural products 1-4 and 10-11 with a pyrrolo[2,1-a]-isoquinoline framework. Moreover, the syntheses of some structural analogs are discussed. The pyrrolo[2,1-a]isoquinolines are of interest due to their promising biological activities. For crispine A (1), many total syntheses have been reported and for trolline (3), only three. Only one total synthesis has been reported for each of the following natural products: peyoglutam (10), mescalotam (11), and the antitumor active crispine B (2). Some of the pyrrolo[2,1-a]isoquinoline alkaloids have not been synthesized yet. The following three tables summarize the synthetic efforts toward crispine A (1) (Table 1: racemic syntheses; Table 2: enantioselective syntheses) and trolline (3) (Table 3).