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A Formal Total Synthesis of (+)‐Methyl Trachyloban‐18‐oate and (+)‐Methyl 16‐Oxo‐17‐norkauran‐18‐oate: Regio‐ and Diastereoselective Preparation of Methyl (13 S )‐13‐Hydroxyisoatisiren‐18‐oate from (−)‐Abietic Acid
Author(s) -
Berettoni Marco,
De Chiara Giovanna,
Iacoangeli Tommaso,
Lo Surdo Paola,
Bettolo Rinaldo Marini,
Di Mirabello Lorenzo Montagnini,
Nicolini Luca,
Scarpelli Rita
Publication year - 1996
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.19960790724
Subject(s) - chemistry , abietic acid , allene , sulfonate , organic chemistry , toluene , stereochemistry , rosin , resin acid , catalysis , sodium
A novel preparation of methyl (13 S )‐13‐hydroxyisoatisiren‐18‐oate ( 4 ), a key‐intermediate in a synthesis of (+)‐methyl trachyloban‐18‐oate ((+)‐ 1 ), from (−)‐abietic acid, is described. Since (−)‐ 1 has been previously converted into (−)‐methyl 16‐oxo‐17‐norkauran‐18‐oate ((−)‐ 16 ), our preparation of 4 constitutes also a formal total synthesis, from (−)‐abietic acid, of (+)‐ 16 . Key steps in this approach were the allene photoaddition to podocarp‐8(14)‐en‐13‐one ( 5 ) and the conversion of the endo ‐toluene‐4‐sulfonate 11 into the exo ‐benzoate 12b .