Syntheses of DL ‐Serine and of Precursors thereof (Glycolaldehyde and “Masked” Glycolaldehydes)

On treatment of vinyl chloride epoxide ( 4 ) with water, of chloroethylene carbonate ( 9 ) with aqueous bases, of vinyl acetate ( 1 ) or ethyl vinyl ether ( 6 ) with aqueous potassium chlorate and catalytic amounts of osmium tetroxide, glycolaldehyde ( 5 ) was formed (scheme 1). The not isolated aldehyde 5 , when submitted to the Zelinsky‐Stadnikoff amino acid synthesis, afforded DL ‐serine in 70% yield. The latter method, when applied directly to the “masked” glycolaldehydes 2 , 7 , 9 , 10 , vinylene carbonate ( 11 ), 13 or 14 , also gave DL ‐serine (yields 35–70%), whereas with 4 no serine formation could be detected (scheme 1).