4-取代-2,6-二(羟甲基)苯酚的选择氧化

酚类由于本身容易氧化,仅在非常温和的条件下才能直接使4-取代-2,6-二(羟甲基)苯酚中的羟甲基氧化成醛基。文献报道了用活性二氧化锰可以将2,6-二(羟甲基)-4-甲基苯酚氧化成2-羟基-5-甲基-1,3-苯二甲醛,但要使两个羟甲基中只有一个被氧化却是困难的。文献报道了由芳氧基溴化镁与甲醛作用制备水杨醛类化合物的方法,并认为中间产物是邻羟甲基苯酚的镁盐,后者与甲醛之间通过负氢离子转移的分子间氧化还原反应生成相应

Selective oxidation of 4-substituted-2,6-di(hydroxymethylphenols

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.