Abstract
The Birch reduction of biaryls generally converts one of the two arenes into a cyclohexa-1,4-diene.
Biaryls are more reactive than monocyclic arenes under the Birch conditions. Unlike
the reduction of monocyclic arenes, biaryl reduction proceeds through two consecutive
electron transfer steps before the protonation of the dianion intermediate. The biaryl
reductions and subsequent alkylations in one pot rapidly increase the molecular complexity
and thus have been used in the synthesis of natural products and drug-like molecules.
1 Introduction
2 The Physical Organic Chemistry of the Birch Reduction of Biaryls
3 Biaryls as the Mediators of Electron Transfer
4 Methods for the Dissolving-Metal Reduction of Biaryls
5 Intercepting the Biaryl Reduction Intermediates with Electrophiles
6 Synthetic Applications of the Dissolving-Metal-Mediated Reductions of Biaryls
7 Outlook
Key words
lithium - sodium - reduction - electron transfer - Birch - biphenyl - cyclohexa-1,4-diene
