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Synthese von (+)‐(5 S , 6 S )‐Azafrin‐methylester; absolute Konfiguration von Aeginetinsäure and von weiteren vicinalen Apocarotin‐diolen
Author(s) -
Eschenmoser Walter,
Uebelhart Peter,
Eugster Conrad Hans
Publication year - 1982
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.19820650137
Subject(s) - chemistry , vicinal , absolute configuration , stereochemistry , enantiomer , optically active , absolute (philosophy) , ring (chemistry) , organic chemistry , philosophy , epistemology
Synthesis of (+)‐(5 S , 6 S )‐Azafrin Methyl Ester; Absolute Configuration of Aeginetic Acid and of Further Vicinal Apocarotenediols We describe the synthesis of a series of optically active vicinal apo‐β‐carotenediols. Thus, starting from (+)‐(5 S , 6 S )‐5,6‐dihydroxy‐5,6‐dihydro‐β‐ionone ( 2 ) we have prepared the ( Z/E )‐isomeric (+)‐C 15 ‐esters 7 and 8 , the (+)‐retinoic derivatives 14 , 15 , 18 , 19 and (+)‐methyl azafrinate ( 22 ), the enantiomer of the naturally occur‐ring compound (s. Scheme 1 ). Our synthesis also establishes the absolute configura‐tion of aeginetic acid ( 24 ), aeginetoside ( 25 ) and aeginetin ( 26 ), compounds isolated from the root parasite Aeginetia indica by Indian and Japanese workers (s. Scheme 2 ). The presented synthesis of optically active methyl azafrinate confirms our previous assignment [14] of the absolute configuration of azafrin ( 1a ), which was based on degradative evidence.