Catalytic Asymmetric Total Syntheses of Naturally Occurring Amarylidaceae Alkaloids, (-)-Crinine, (-)- epi-Crinine, (-)-Oxocrinine, (+)- epi-Elwesine, (+)-Vittatine, and (+)- epi-Vittatine.
Mrinal K DasNivesh KumarAlakesh BisaiPublished in: Organic letters (2018)
An expeditious approach to catalytic enantioselective total syntheses of crinine-type Amaryllidaceae alkaloids has been accomplished via a Pd-catalyzed enantioselective decarboxylative allylation of allylenol carbonates as a key step (up to 96% ee). Using this strategy, collective total syntheses of Amaryllidaceae alkaloids such as (-)- epi-elwesine (1b), (-)-crinine (1c), (-)- epi-crinine (1e), (-)-oxocrinine (1f), and (-)-buphanisine (1d) have been accomplished. Gratifyingly, naturally occurring Amaryllidaceae alkaloids such as (+)-vittatine (1g), (+)- epi-vittatine (1h), and (+)- epi-elwesine (1i) [enantiomers of (-)-1c, (-)-1e, and (-)-1b, respectively] have also been achieved by switching the antipode of ligand used in the catalytic enantioselective step.
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