Total syntheses of (±)‐cis‐ and trans‐11‐methoxydeethyleburnamonine |
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Authors: | Kalle Rnkk Mathias Berner Reija Jokela Arto Tolvanen |
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Institution: | Kalle Rönkkö,Mathias Berner,Reija Jokela,Arto Tolvanen |
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Abstract: | The total syntheses of 11‐methoxydeethyleburnamonines ( 4 ) and ( 13 ) were carried out with use of 6‐methoxytryptophyl bromide ( 5 ) as starting material. Compound 5 was converted in three steps to trans‐ester 8 . Acid‐catalysed epimerization of 8 , lithium aluminum hydride reduction of the ester group, tosylation and substitution with cyanide gave the cis‐nitrile 12 . Acid‐induced cyclization of 12 yielded mainly (±)‐trans‐11‐methoxydeethyleburnamonine ( 13 ), whereas base‐induced cyclization gave (±)‐cis‐11‐methoxydeethyleburnamonine ( 4 ). |
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