dl-Isoserine and Related Compounds

Article abstract of DOI:10.1021/jo00201a018

Syntheses of dl-isoserine (3-amino-2-hydroxypropanoic acid, 7) and further functionalized derivatives are described.Reaction of glyoxylic acid with nitromethane gives the known 2-hydroxy-3-nitropropanoic acid (8), which upon hydrogenolysis affords dl-isoserine in high yield.The comparable nitro-aldol reaction of 3-nitropropanal ethylene acetal (2) with glyoxylic acid produces 2-hydroxy-3-nitro-5-oxopentanoic acid ethylene acetal (4a) as a mixture of erythro and threo isomers.The methyl esters of hydroxy acid 4a are chromatographically separable as the tert-butyldimethysilyl ethers.Catalytic reduction (Pd/C) of these nitro compounds gives the corresponding methyl 3-amino-2-hydroxy-5-oxopentanoate ethylene acetals 9.Ethyl 2-hydroxy-3-phthalimidopropanoate (22) and ethyl 2-oxo-3-phthalimidopropanoate (23) were also prepared along with several other N-protected β-amino-α-oxy esters related to isoserine.