C([Mg]Br)C.[CH2:5]([C:7]1[CH:8]=[C:9]([OH:13])[CH:10]=[CH:11][CH:12]=1)[CH3:6].[CH2:14]=[O:15].CN(C)P(N(C)C)(N(C)C)=O>O1CCCC1.C1(C)C=CC=CC=1>[CH2:5]([C:7]1[CH:12]=[CH:11][C:10]([CH:14]=[O:15])=[C:9]([OH:13])[CH:8]=1)[CH3:6]A stirred solution of 200 mL (0.20 mole) of 1.0M of ethylmagnesium bromide (in tetrahydrofuran) in 100 mL of tetrahydrofuran was cooled in an ice-bath and 25.0 grams (0.21 mole) of 3-ethylphenol was added dropwise. Upon completion of addition, the reaction mixture was allowed to warm to ambient temperature where it stirred for 30 minutes. After this time, 15.4 grams (0.51 mole) of paraformaldehyde, 36.7 grams (0.21 mole) of hexamethylphosphoramide, and 350 mL of toluene were added. Upon completion of addition, the reaction mixture was heated to 80° C. where it stirred for about 18 hours. The reaction mixture was then cooled and concentrated under reduced pressure to a residue. The residue was taken up in diethyl ether and 200 mL of an aqueous 10% hydrochloric acid solution was added. The aqueous layer was separated and extracted with diethyl ether. The extract was combined with the organic layer, and the combination was washed with water. The organic layer was dried with magnesium sulfate and filtered. The filtrate was concentrated under reduce pressure to a residue. The residue was subjected to column chromatography on silica gel, using 1:1 hexane and methylene chloride as the eluant. The product-containing fractions were combined and concentrated under reduced pressure, yielding 21.8 grams of 5-ethyl-2-formylphenol. The NMR spectrum was consistent with the proposed structure.
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