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DOI: 10.1055/sos-SD-021-00911

Whitehead, A.; Sieck, S. R.; Mukherjee, S.; Hanson, P. R.Science of Synthesis, (200521922.

Little was known about the enolization properties of α-oxo phosphonates until 1997 when the first transformation of acylphosphonates into their enol tautomers was reported (Scheme 17).[‌50‌] The starting acylphosphonates 55 are available from the corresponding acid chlorides 54 and trimethyl phosphite. Using mild bases such as triethylamine and treatment with acetic anhydride, the acetyl enol ethers 56 are formed with exclusive E configuration. This process is sensitive to the substituents at phosphorus and the alkyl side chain. If R1 is substituted with aromatic groups, good yields are reported (5774%); modest yields (3555%) are reported when R1 is nonaromatic. Subsequent work in the area has been directed to the application of enolates derived from acylphosphonates.

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