Many biologically active natural products, such as sugars and antibiotics, contain α-hydroxy carbonyl units. These have been abundantly used as a versatile chiral building block for the asymmetric synthesis of more complex molecular architectures. However, efficient methods for the preparation of chiral acyclic tertiary α-hydroxy carbonyl species are lacking. This is mainly due to the difficulty to prepare stereodefined polysubstituted enolates or silyl ketone aminals possessing two different alkyl groups on the sp² carbon center.

Jian Qiang Huang, Zackaria Nairoukh, and Ilan Marek, Technion-Israel Institute of Technology, Haifa, have developed a practical approach to acyclic tertiary α-hydroxy carbonyl compounds with excellent diastereoselectivity in only two chemical steps. The synthesis starts with a combined carbometalation-oxidation-silylation of alkynes. Stereodefined polysubstituted silyl ketone aminals are formed. The second step is an electrophilic oxidation reaction to acyclic tertiary α-oxidized carbonyl compounds possessing two different alkyl groups.

The products could be smoothly converted to synthetically useful enantiomerically enriched 1,2-diol derivatives.

• Electrophilic Oxidation of Stereodefined Polysubstituted Silyl Ketone Aminals,
  Jian Qiang Huang, Zackaria Nairoukh, Ilan Marek,
  Eur. J. Org. Chem. 2017.
  https://doi.org/10.1002/ejoc.201701516