TOTAL SYNTHESIS OF MONTANINE-TYPE AMARYLL IDACEAE ALKALOIDS, (+ -)-MONTANINE, (+/-)-COCCININE, (+/-)-PANCRACINE, AND (+/-)-BRUNSVIGINE/

The first stereoselective total syntheses of the montanine-type Amaryl lidaceae alkaloids, (+/-)-montanine 1, (+/-)-coccinine 2, (+/-)-pancra cine 4, (+/-)-O-acetylmontanine 5, and (+/-)-brunsvigine 6 are describ ed. The key steps in the reaction sequences are as follows : (1) stere oselective hydroboration-oxidation of exomethylene by means of an intr amolecular charge transfer complex to provide alcohol 44 as a single i somer, (2) cyclization of tosylamide alcohol 49 with vitride(R) [sodiu m bis(2-methoxyethoxy)aluminum hydride] to provide functionalized 5,11 -methanomorphanthridine 50, which possesses the basic skeleton of mont anine-type alkaloids; and (3) conversion of 56 to allylic chloride 57 a by treatment with PhSeCl in MeOH under ultrasonication followed by N aIO4 oxidation. A formal total synthesis of (+/-)-manthine 3 was also achieved.