872831-86-2Relevant academic research and scientific papers
Asymmetric total synthesis of the 1-epi-aglycon of the cripowellins A and B
Enders, Dieter,Lenzen, Achim,Backes, Michael,Janeck, Carsten,Catlin, Kelly,Lannou, Marie-Isabelle,Runsink, Jan,Raabe, Gerhard
, p. 10538 - 10551 (2007/10/03)
The unusual [5.3.2]-bicyclic structure of the insecticidal Amaryllidaceae alkaloids cripowellin A (1) and B (2) has been synthesized for the first time via a sequence of Sharpless dihydroxylation, ring-closing metathesis, and intramolecular Heck reaction. The asymmetric synthesis of the 1-epi-aglycon 82 proceeds with virtually complete diastereo- and enantioselectivity (de, ee ≥ 98%) in 13 steps and an overall yield of 5.6%. In addition, three alternative approaches toward the aglycon 3 are also described focusing on (1) the alkylation of the 2-benzazepinedithianes 35 and 36 with the electrophile 11, (2) a radical cyclization of the precursor (R/S,S,S)-39, and (3) an intramolecular arylation reaction of the aryl ketone 47.
