Prechelmacher, S., Mereiter, K., & Hammerschmidt, F. (2018). The α-hydroxyphosphonate-phosphate rearrangement of a noncyclic substrate - some new observations. Organic and Biomolecular Chemistry, 16(19), 3672–3680. https://doi.org/10.1039/c8ob00419f
Racemic ethyl hydrogen (1-hydroxy-2-methylsulfanyl-1-phenylethyl)phosphonate was resolved with (R)-1-phenylethylamine. The (R)-configuration of the (-)-enantiomer was determined by chemical correlation. Esterification of the (-)-enantiomer with a substituted diazomethane derived from 3-hydroxy-1,3,5(10)-estratrien-17-one delivered two epimeric phosphonates separated by HPLC. Methylation with methyl fluorosulfate at the sulfur atom and treatment with a strong base induced an α-hydroxyphosphonate-phosphate rearrangement with formation of dimethyl sulphide and two enantiomerically pure enol phosphates. Their oily nature interfered with a single crystal X-ray structure analysis to determine the stereochemistry at the phosphorus atom.
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