Concise enantioselective synthesis of 3,5-dialkyl-substituted indolizidine alkaloids via sequential cross-metathesis-double-reductive cyclization.
An efficient stereoselective synthesis of two 3,5-dialkyl-substituted indolizidine alkaloids is reported. The convergent syntheses are based on a novel sequence of a cross-metathesis (CM) reaction of an alpha,beta-unsaturated ketone and a chiral homoallylic amine followed by a domino reaction involving hydrogenation, N-deprotection, and two diastereoselective reductive aminations. Our concept presents one of a few examples of a highly selective CM reaction in the synthesis of a natural product.
Randl
Stefan
S
Technische Universität Berlin, Institut für Chemie, Strasse des 17. Juni 135, D-10623 Berlin, Germany.
Blechert
Siegfried
S
D000470:Alkaloids / Q000138:chemical synthesis*; D007212:Indolizines / Q000138:chemical synthesis*; D009682:Magnetic Resonance Spectroscopy; D013058:Mass Spectrometry; D010084:Oxidation-Reduction; D013055:Spectrophotometry, Infrared; D013237:Stereoisomerism
D000470:Alkaloids; D007212:Indolizines