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26.6.8.1.2 Method 2: Synthesis from Silyl Enol Ethers by Aminohydroxylation

DOI: 10.1055/sos-SD-026-00761

Suffert, J., Science of Synthesis, (2005) 26, 955.

Certain silyl enol ethers undergo asymmetric aminohydroxylation when treated with osmium(VIII) oxide in the presence of dihydroquinidinium 4-chlorobenzoate, or dihydroquinidine/pyrimidine as chiral ligands, and chloramine-T as a nitrogen source.[‌232‌] Unfortunately, yields are modest (34–40%) and the enantiomeric excesses obtained are variable (70–92%). For example, 1-(trimethylsiloxy)cyclohexene, when subjected to aminohydroxylation at 25°C with dihydroquinidinium 4-chlorobenzoate and chloramine-T in a mixture of tert-butyl alcohol and water, gives the α-amino ketone ‌273‌. Although the yield is only 35%, the enantiomeric excess is 92% (‌Scheme 122‌).

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References

[232] Meeeee, M.; Meeeeee, M., Meeeeeeeeee: Meeeeeeee, (8888) 8, 8888.

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