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Synthesis of (1 S ,5 S )‐4,5‐Dihydro‐1,5‐epoxy‐1 H ‐2‐benzoxocin‐6(3 H )‐one from ( S )‐Malic Acid Derivatives
Author(s) -
Wünsch Bernhard,
Diekmann Heike
Publication year - 1996
Publication title -
liebigs annalen
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 0947-3440
DOI - 10.1002/jlac.199619960111
Subject(s) - chemistry , substituent , electrophile , ketone , acetal , aldehyde , benzaldehyde , alcohol , organic chemistry , medicinal chemistry , stereochemistry , catalysis
The homochiral 1,3‐dioxanes 8a–e with a 2‐bromophenyl substituent in position 2 and an electrophilic group in position 4 were stereo‐ and regioselectively prepared from the ( S )‐malic acid derivatives 6a, 6b, 11 , and 14 . Attempts to prepare the tricycles 5a–c by connecting the 2‐phenyl substituent with the electrophilic groups in position 4 of 8a–e in a Parham cyclization across the 1,3‐dioxane ring failed. The synthesis of the tricyclic title ketone 5a succeeded, however, by addition of the lithiated benzaldehyde acetal 7c to the protected α‐hydroxylactone 10b and subsequent treatment of the intermediate ketone 23 with acid. The acid hydrolysis of the alcohol 26 , which was obtained by addition of 7c to the protected dihydroxy aldehyde 25b , followed by oxidation of the resulting alcohols 27a and b represent a second possibility for the preparation of the tricyclic ketone 5a .