A Tandem Semipinacol Rearrangement/Aldehyde Arylation or Alkylation of Trisubstituted 2,3-Epoxy Alcohols with Grignard Reagents for Functionalized 1,3-Diols

A tandem semipinacol rearrangement/aldehyde arylation or alkylation reaction leading to formation of functionalized 1,3-diols bearing three consecutive tertiary stereocenters is identified from the reaction of various new trisubstituted 2,3-epoxy alcohols with numerous Grignard reagents. This reaction is useful for stereoselective construction of three consecutive tertiary stereocenters. The observed 1,3-diols exist in the anti configuration, which is confirmed by two-dimensional nuclear Overhauser effect spectroscopy, the crystal structure of acetonide of 1,3-diol analogue 3ai, and further density functional theory studies.