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Investigations on the Reactivity of Fascaplysin, Part II, General Stability Considerations and Products Formed with Nucleophiles
Author(s) -
Fretz Heinz,
UcciStoll Katharina,
Hug Paul,
Schoepfer Joseph,
Lang Marc
Publication year - 2001
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/1522-2675(20010418)84:4<867::aid-hlca867>3.0.co;2-a
Subject(s) - chemistry , deprotonation , pyridinium , methoxide , nucleophile , ring (chemistry) , reagent , pyridine , reactivity (psychology) , oxime , medicinal chemistry , aqueous solution , molecule , methanol , organic chemistry , ion , catalysis , medicine , alternative medicine , pathology
Reversible deprotonation of fascaplysin ( 1 ) was achieved with non‐nucleophilic bases ( Scheme 1 ). Under basic aqueous conditions, opening of ring D of 1 occurred, yielding zwitter‐ionic reticulatine 2a , whereas, in a methoxide‐containing MeOH solution, an unexpected addition of three molecules of MeOH to the pyridinium ring produced an isomer mixture 3 of a trimethoxy‐substituted compound ( Scheme 2 ). Transformation of the keto group of 1 to the oxime 4A took place in the presence of pyridine as base ( Scheme 3 ). Grignard and alkyllithium reagents added as expected to the keto group of 1 , providing tertiary alcohols 5 and 6 ( Scheme 4 ).