A Temporary Stereocentre Approach for the Stereodivergent Synthesis of Either Enantiomer of α-Methyloctanal

The aldol reaction of a chiral N-(acyl)oxazolidin-2-one with 2-methyleneoctanal or (E)-2-methyloct-2-enal affords chiral aldol products whose alkene functionalities were hydrogenated using Brown's or Wilkinson's catalyst to afford syn- or anti-selective products with excellent levels of diastereocontrol. Subsequent retro-aldol cleavage of these syn- or anti-adducts resulted in the formation of either (R)- or (S)-enanti-omer of α-methyloctanal with no racemisation occurring, which could be derivatised in-situ to afford chiral dithiane, alcohol or α,β-unsaturated ester products in enantiopure form.