An Eight‐Step Total Synthesis of Pyrroloquinolone‐TypeLycopodium Alkaloid via a Tandem Annulation Approach^†

Abstract

of main observation and conclusion A total synthesis of 6,7,9,10,12,12a-hexahydro-2-methyl-(2R,4aS,12aS)-2H,5H-benzo[e]pyrrolo-[3,2,1-ij]quinolone-4,11(1H,3H)-dione (1), a unique pyrroloquinolone-type Lycopodium alkaloid containing a complex 6/6/6/5 tetracyclic core, has been disclosed in eight steps and 38% overall yield. The reported synthesis features a short, efficient synthesis of the crucial multi-substituted cyclohexanone intermediate with three stereogenic centers, and one-pot generation of the complex 6/6/6/5 tetracyclic core in a single tandem step.

Synthetic Studies on Tetracyclic Diquinane Lycopodium Alkaloids Magellanine, Magellaninone and Paniculatine

“…The piperidine ring of 88 could be derived from the reductive amination of aldehyde 89 , which itself could be obtained from an intramolecular Michael addition of 90 , a common procedure for 1,5-dicarbonyl systems. The enone moiety of 90 could come from the dehydration of tertiary alcohol 91 , for which the latter could come from an intramolecular reductive C-C bond formation between the two carbonyls in 92 [ 99 , 100 , 101 ]. Methyl ester 92 can result from a functionally decorated intermediate 93 , which, in turn, can be derived from a four-step sequence of the Morita–Baylis–Hillman reaction, alcohol oxidation, and two Michael additions.…”