500213-30-9Relevant academic research and scientific papers
Synthesis of optically active 2-acetoxy-3-Alkylidene-α-lycoranes for a synthetic approach toward (+)-lycorine by radical reaction
Ishizaki, Miyuki,Kai, Yuichiro,Hoshino, Osamu
, p. 2279 - 2297 (2007/10/03)
A radical-mediated synthesis of optically active 2α- and 2β-trimethylsilylmethyene-α-lycoranes (3,4), which are key intermediates for synthesis of (+)- lycorine (2), is described. Thus, both B and C rings in lycorine (2) were constructed by 6-exo mode radical cyclization. The former ring formation was performed in diastereoselective manner by radical cyclization via α-acylamino radical of (4S,5R)-4-acetoxy-N-(2-methoxy-, benzyloxy-, and tert-butoxy-carbonylethenyl-4,5-methylenedioxybenzyl)- or (4S,5R)-N-(2-tert- butoxycarbonylethenyl-4,5-methylenedioxybenzyl)-4-triethylsilyloxy- 5-phenyl-selenyl-2-pyrrolidinones (10-12 or 19). The latter ring formation was accomplished by the reaction of (1S, 10R, 10aR,2′S)- and (1S, 10R, 10aR,2′R)-10- (2′-acetoxy-4′-trimethylsilyl-3′-butynyl)-1- imidazolylthiocarbonyloxy-7,8- methylenedioxy-1,2,3,5,10,10a-hexahydrobenz[f]indolizidines (28).
