[CH3:1][C:2]1[CH:7]=[C:6]([CH3:8])[CH:5]=[CH:4][C:3]=1[OH:9].CN(P(N(C)C)(N(C)C)=O)C.[CH2:21]=[O:22]>C1(C)C=CC=CC=1.C([Mg]Br)C>[OH:22][C:21]1[C:2]([CH3:1])=[CH:7][C:6]([CH3:8])=[CH:5][C:4]=1[CH:3]=[O:9]To a solution of 2,4-dimethylphenol (24.9 g, 204 mmole) in anhydrous toluene (75 mL) at 0° C. was added HMPA (35 mL) and then a solution of ethylmagnesium bromide (61 mL-3 M in ethyl ether, 0.183 mmole), keeping the temperature <10° C. Then paraformaldehyde (13 g, 0.43 mole) was added and the cooling was removed. The ethyl ether was removed by distillation and the mixture was refluxed. The mixture was quenched with 10% HCl and EtOAc was added. The EtOAc solution was washed twice with H2O, twice with aqueous NH4Cl, dried over Na2SO4 and concentrated in vacuo. Purification by silica chromatography (98:2 hexanes:EtOAc) gave 17.9 g (59% yield) of the product as a yellow oil: ESHRMS m/z 147.0619 (M−H, C9H9O2, Calc'd 147.0603).
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