Prianosins total synthesis

Our group accomplished the total syntheses of discorhabdin C in 1992 [38], makaluvamine F in 1999 [39, 40], and discorhabdin A in 2002 [41, 42]. We also accomplished the first total synthesis of prianosin B in 2009 [43]. We now report the progress towards the synthesis of pyrroloiminoquinone alkaloids, mainly since 2000 including our studies, in this chapter. 

Discorhabdin alkaloids have the richest structure-diversity among the marine pyrroloiminoquinone alkaloids, and new discorhabdins are still being discovered. Although many synthetic studies have been carried out, only a few total syntheses of the natural discorhabdins have been reported. The total synthesis of discorhabdin C was accomplished by our group and Yamamura s group at almost the same time, and later by the Heathcock group. Heathcock et al. also synthesized discorhabdin E at the same time. Those discorhabdins are rather simple. The more complex discorhabdins, discorhabdin A and prianosin B, were synthesized only by us. 

Prianosin B is the oxidized discorhabdin A, whose C16-17 bond is double bond. We found that the detosylation and dehydrogenation reaction of the pyrroloiminoqumone unit proceeded using a catalytic amount of NaN3 in good yield. We then applied the reactions to the total synthesis of prianosin B (Scheme 33). Thus, the treatment of 98... 

Wada Y, Otani K, Endo N, Harayama Y, Kamimura D, Yoshida M, Fujioka H, Kita Y (2009) The first total synthesis of prianosin B. Tetrahedron 65 1059-1062... 

Nishiyama S, Cheng JF, Tao XL, Yamamura S (1991) Synthetic studies on novel sulfur-containing alkaloids, prianosins and discorhahdins total synthesis of discorhabdin C. Tetrahedron Lett 32 4151-4154... 

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