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Please login to access the full content or check if you have access via Variation 4: Hydrolysis of α,α-Dihalo Ketones

DOI: 10.1055/sos-SD-026-00532

Landais, Y.; Vincent, J. M.Science of Synthesis, (200526671.

α,α-Dihalo ketones are quite sensitive to hydrolysis. Mild reagents such as sodium acetate in acetic acid are most frequently used to generate the corresponding 1,2-diketones as illustrated by the conversion of 118 into 119 (Scheme 29).[‌93‌] It has been noted that the presence of neighboring electron-withdrawing trifluoromethyl groups facilitate the hydrolysis.[‌94‌,‌95‌] Bromination of 1,3-diketone 117 gives the 2,2-dibromo-1,3-diketone 118 in good yield and subsequent hydrolysis gives the 1,2,3-trione 119, thus providing a two-step access to 1,2,3-triones from the corresponding 1,3-diketones.[‌93‌,‌95‌] Other methods are used to convert α,α-dihalo ketones into 1,2-diketones, such as silver tetrafluoroborate in wet acetonitrile or tetrahydrofuran.[‌96‌] Transformation of the dibromo group in 120 into a ketone function in 121 is rationalized by invoking a stepwise substitution of the bromine atoms by hydroxy groups; similarly, treatment of 120 with methanol yields the corresponding α-oxo ketal. Mercury(II) fluoride is used for the conversion of 3,3-difluorobutan-2-one (122) into butane-2,3-dione (123); in this case, the mechanism of the transformation is unknown.[‌97‌]

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