Diethyl 1-substituted-1-perfluoroalkenyl phosphates (1), available from perfluoroalkyl ketones and sodium diethyl phosphite, were allowed to react with a reagent derived from lithium aluminum hydride and a metal salt or brominein tetrahydrofuran below -30 °C and successively treated with water or aldehydes to give rise to the corresponding 1H-perfluoroalkyl ketones (4) or a-fluoro-a-perfluoroalkyl-β-hydroxy ketones (5), respectively, in moderate to good yields. Copper(II) bromide, copper(I) bromide, and zinc chloride could be employed as the metal salt in the reaction. The phosphates also underwent reductive dephosphorylation with diisobutylaluminum hydride to generate the aluminum enolates of 1H-perfluoroalkyl ketones. 19F NMR analyses indicated that their structure is not an α-metallo ketone but an oxygen-metalated species and that they are appreciably stable below 0 °C. Treatment with a wide variety of aldehydes at 0 °C yielded the corresponding aldol products 5 in good to excellent yields, whereas ketones did not react.
ASJC Scopus subject areas
- Organic Chemistry