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Synthesis of Aristotelia ‐Type Alkaloids. Part VI Biomimetic Synthesis of (+)‐Aristofruticosine
Author(s) -
Beerli René,
Borschberg HansJürg
Publication year - 1991
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/hlca.19910740113
Subject(s) - chemistry , indole alkaloid , imine , stereochemistry , indole test , total synthesis , acetaldehyde , synthon , amine gas treating , moiety , intramolecular force , reagent , protecting group , nucleophile , organic chemistry , ethanol , alkyl , catalysis
( S )‐Perilla alcohol ( 5 ) was transformed into ( S )‐7‐(phenylthio)‐ p ‐menth‐1‐en‐8‐amine ( 11 ) in five steps. Condensation of this building block with 1‐(4‐methoxyphenylsulfonyl)‐1 H ‐indole‐3‐acetaldehyde ( 12 ) led to the expected imine 15 which cyclized in 54% yield to protected 20‐(phenylthio)hobartine 16 upon exposure to anh. HCOOH. Treatment of this intermediate with an alkylating reagent led to (+)‐aristofruticosine protected in the indole moiety via an intramolecular, allylic nucleophilic displacement reaction. Subsequent reductive removal of the protecting group completed the first synthesis of the Aristotelia alkaloid (+)‐aristofruticosine ((+)‐ 4 ). This straightforward synthesis confirmed the tentative structure (+)‐ 4 , proposed by Bick and Hai , and established the hitherto unknown absolute configuration of this metabolite.