Domino Grignard Addition/Cope-House Reaction for the Synthesis of Polyhydroxylated 3-Methylindolizidines Analogous to
Thomas Lulli1, Filippo Dei1, Macarena Martínez-Bailén1
1Dipartimento di Chimica 'Ugo Schiff' (DICUS), Università di Firenze, via della Lastruccia 3-13, 50019 Sesto Fiorentino (FI), Italy.
Abstract:
The first synthesis of polyhydroxylated 3-methylindolizidines is reported. A straightforward domino butenylmagnesium bromide addition/Cope-House reaction to carbohydrate-derived nitrones afforded efficiently the methyl pyrrolidine moiety with good stereoselectivity, which can be reversed by use of Lewis acids. A subsequent one-pot deprotection/deoxygenation/reductive amination step furnished the desired bicyclic architecture, allowing us to afford the desired final products in 3-4 steps from the starting nitrones and 18-30% overall yields.
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