Hydrochloric Acid → 3-(4,4'-Dichlorobiphenyl-3-yl)-8,8-difluoro-4-hydroxy-1-azaspiro[4.5]dec-3-en-2-one

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Reaction Steps

3.20 g (5.74 mmol) of the compound from Example 8A were initially charged in a solution of 14 ml of DMA (N,N-dimethylacetamide), a solution of 9 ml of DMA and 1.69 g (2.5 eq.) of potassium tert-butoxide was added dropwise at 20° C. and the mixture was stirred at room temperature for 4 h. The mixture was poured into 200 ml of water and the reaction was adjusted to pH 2 using concentrated aqueous hydrochloric acid, and the resulting residue was filtered off with suction. Purification by flash column chromatography (silica gel; ethyl acetate/n-hexane 1:1) gave 1.50 g (52% of theory) of the title compound of melting point m.p. 156° C.

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