High Asymmetric Induction in Conjugate Additions of RCu · BF3 to Chiral Enoates. Preliminary communication

✍ Scribed by Wolfgang Oppolzer; Heinz J. Löher

• Book ID: 102251757
• Publisher: John Wiley and Sons
• Year: 1981
• Tongue: German
• Weight: 258 KB
• Volume: 64
• Category: Article
• ISSN: 0018-019X
• DOI: 10.1002/hlca.19810640842

✦ Synopsis

Abstract

1,4‐Additions of PhCu · BF~3~, n‐Bu · BF~3~ and MeCu · BF~3~ to the trans‐8‐phenyl‐menthyl enoates 1 proceeded with high chiral induction. Saponification of the resulting esters 2 gave the corresponding enantiomerically pure β‐substituted alkanoic acids 3 and the recovered (−)‐8‐phenylmenthol in good overall yields. Analogous additions to the cis‐crotonate 1 led preferentially to the acids 3 enantiomeric to those obtained from the trans‐crotonate 1, although with lower selectivity. A stereochemical model is proposed consistent with the observed results (Scheme 2, Table).