Zhang Y.-A,
Gu X,
Wendlandt AE.
*
Massachusetts Institute of Technology, Cambridge, USA
A Change from Kinetic to Thermodynamic Control Enables
trans-Selective Stereochemical Editing of Vicinal Diols.
J. Am. Chem. Soc. 2022;
144: 599-605
DOI:
10.1021/jacs.1c11902
Key words
iridium catalysis - photocatalysis - diols - thermodynamic control -
trans selectivity
Significance
The Wendlandt group reports a selective catalytic isomerization of cis-1,2-diols to trans-diequitorial-1,2-diols via photoredox catalysis. The use of Ph3SiSH was found to be essential, as the nature of the silanethiol catalyst influenced the product distribution of the two isomers. The reaction was amenable to a variety of 1,2-diols and as well as mixtures of diastereomers, giving a single product isomer.
Comment
A series of mechanistic experiments revealed that, under the optimal conditions, the H-atom abstraction and donation steps were mediated by the Ph3SiSH catalyst. The amine additive served as a base, not as a H-atom abstractor. The authors conclude that since the H-atom abstraction process is reversible, the equilibrium ratio represents the thermodynamic product distribution of the isomers.
