Total Syntheses of Carbohydrates, II. Dl -Erythrose and Dl -Threose

Propargyl alcohol was converted into 4-acetoxy-cis-crotonaldehyde diethyl acetal (III) via three steps, cis-Hydroxylation of III with potassium permanganate followed by acetylation yielded tri-O-acetyl-Dl-erythrose diethyl acetal (IV). Hydrolysis of IV afforded syrupy Dl-erythrose (VI) which could be converted into erythritol (VII) and its dibenzylidene derivative. An acid hydrolysis of III gave 4-acetoxy-crotonaldehyde (VIII) which was converted into triacetyl-Dl-threose diethyl acetal (XI) or Dl-threose pentaacetate (XII). Hydrolysis of XI and XII gave syrupy Dl-threose which could be identified as di-benzylidenethreitol.