Structure Identification: |
Science China-Chemistry, 2013, 57(2):252-264. | A novel and versatile method for the enantioselective syntheses of tropane alkaloids.[Reference: WebLink] | METHODS AND RESULTS: A full account of the novel and flexible approach to hydroxylated 8-azabicyclo[3,2,1]octan-3-ones and 9-azabicyclo[3,3,1] nonan-3-ones is presented. Using keto-lactams as the starting materials, this two-step method consists of silyl enol ether formation with TBDMSOTf, lactam activation with Tf2O/DTBMP, and halide-promoted cyclization. Radical dechlorination of the resulting 1-halotropan-3-ones led to the corresponding hydroxylated tropan-3-ones, which can be hydrogenated to yield 3α,6β-dihydroxytropanes.
CONCLUSIONS:
Starting from optically active keto-lactams, the method has been applied to the enantioselective syntheses of (+)-(1S,3S,5R,6S)-pervilleine C (6), (+)-(1S,3R,5S,6R)-Valeroidine (3), (+)-(1S,3S,5R,6S)-dibenzoyloxytropane (8), and (+)-(1S,3S,5R,6S)-merredissine (9). |
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