4-Substituted-2,6-bis(hydroxymethyl)phenols were converted to their magnesium salts with ethylmagnesium bromide and then treated with paraformaldehyde to give the corresponding 5-substituted-2-hydroxy-3-hydroxymethyl benzaldehydes. Further oxidation of the second hydroxymethyl group in these products was prevented by the prior formation of an electron-withdrawing formyl group. Thus, benzyl alcs. I (R = Br, Cl, Me, MeO, Ph, R1 = R2 = H; R = Cl, R1 = R2 = Me) gave 75-88% benzaldehydes II.

Key words: PHENOL P, PHENOL P, BENZALDEHYDE P, OXIDATION, TRIETHYL AMINE P, SELECTIVITY, BROMIDE, MAGNESIUM COMPOUNDS, CARBINOL GROUP, CARBINOL GROUP