Novel Synthesis of Optically Active 2‐Ethylhexanoic Acid, 2‐Ethylhexanol, and 2‐Ethylhexylamine via the Asymmetric Favorskii Rearrangement

Abstract

The asymmetric Favorskii rearrangement of optically active α‐haloketones, which are easily prepared from chiral menthyl‐4‐toluenesulfoxide in several steps using primary or secondary amines, yields their corresponding secondary or tertiary chiral amides. The secondary chiral amides were converted to acids or amines using acylation followed by hydrolysis or reduction. In addition, the tertiary amides were directly reduced to alcohol with Super‐Hydride^®.

Keywords:

• Asymmetric Favorskii rearrangement
• enantioselective reactions
• optically active amide

Acknowledgment

We are grateful to Yumiko Kimura and Kouichi Metori for the spectral measurements. We also express great thanks to Hiroshi Hinou, Kumiko Yoshihara, and Ayako Ohigashi for technical research.