Enantioselective desymmetrisation of an epoxytropinone for peduncularine synthesis
A key 7-allyl-8-hydroxy-6-azabicyclo[3.2.1]octan-3-one intermediate in a synthesis of the alkaloid peduncularine is obtained enantioenriched, by desymmetrisation of an achiral 6,7-epoxy-8-azabicyclo[3.2.1]octan-3-one (epoxytropinone). Chiral lithium amide-assisted enantioselective silyl enol ether f...
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Published in | Tetrahedron Vol. 76; no. 52; p. 131701 |
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Main Authors | , , |
Format | Journal Article |
Language | English |
Published |
Elsevier Ltd
25.12.2020
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Subjects | |
Online Access | Get full text |
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Summary: | A key 7-allyl-8-hydroxy-6-azabicyclo[3.2.1]octan-3-one intermediate in a synthesis of the alkaloid peduncularine is obtained enantioenriched, by desymmetrisation of an achiral 6,7-epoxy-8-azabicyclo[3.2.1]octan-3-one (epoxytropinone). Chiral lithium amide-assisted enantioselective silyl enol ether formation then TMSOTf/allyltrimethylsilane/2,6-lutidine-induced rearrangement−allylation proceeded in up to 80:20 er, but modest overall yield. Chiral amines or (thio)ureas replacing 2,6-lutidine gave up to 76:24 er directly from epoxytropinone. A direct, simplified (base-free) process using a BINOL-derived bis(sulfuryl)imide catalyst and allyltrimethylsilane proved the most promising (80%, 83:17 er).
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ISSN: | 0040-4020 1464-5416 |
DOI: | 10.1016/j.tet.2020.131701 |