Stereoselective synthesis of (1R,2S)-2-amino-1,3-diols from (R)-cyanohydrins

Vinyl substituted (1R,2S)-amino alcohols 5 were obtained by addition of vinyl magnesium bromide to the corresponding cyanohydrin O-trimethylsilyl ethers (R)-2. The O-and N-protected vinyl amino alcohols 6 were ozonized at -78 degrees C in methanol yielding (1R,2S)2-amino-1,3-diols 7 in high enantiomeric and diastereomeric excesses. For purification, compounds 7 in some cases were acetylated to give the derivatives (1R,2S)-8. Racemic 6a was converted by oxidative ozonolysis at -78 degrees C in methanolic NaOH solution to the corresponding methyl N-acetyl-beta-hydroxy propanoate 9a. The configuration of (1R,2S)-8a was confirmed by x-ray crystallographic analysis.