Biaryl thionolactones

Bringman et al. have investigated biaryl lactones and biaryl thionolactones as precursors to enantiomerically enriched axially chiral biaryls. Both, the lactones and the thionolactones are configurationally labile. In this method, biaryl products are obtained by coordination of a Lewis acid followed by reductive lactone ring cleavage. Asymmetric induction requires either the Lewis acid or the reducing agent to be chiral. Both approaches have been realized for biaryl thionolactones with mild Ru Lewis acids (Scheme 10.18) [29]. 

The two-fold hydride addition to biaryl-thionolactone complexes followed by decomplexation of the generated ruthenium thiolates yielded the... 

Scheme 5.18 Preparation of biaryl-thionolactone-mthenium complexes.

Scheme 5.19 Two-fold hydride addition to biaryl-thionolactone complexes.

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