Selective oxidation of benzylic and allylic alcohols to their corresponding aldehyde/ketone derivative without affecting saturated alcohols is still a challenging endeavor in organic synthesis. Various metal complexes, especially the copper complexes in the presence of TEMPO are being used very often for such transformations under aerobic conditions, but they are not selective to allylic and benzylic alcohols. The use of copper salt for oxidation of alcohols in the absence of a ligand are very scarcely studied except for the one catalyzed by CuCl/TEMPO where chloride inhibition and lack of selective oxidation have been noted upon use of CuCl₂. Herein we report a Cu(OAc)₂ catalyzed and TEMPO mediated selective aerobic oxidation of benzylic and allylic alcohols to aldehyde/ketone in the presence of Et₂NH. The method avoids pre-synthesis of the catalyst as in the case of Cu(II)/(I) complexes/TEMPO catalyzed oxidation reactions, requires low catalyst loading, employs cheaper copper salt, and gives excellent selectivity for oxidation of benzylic and allylic alcohols.

中文翻译：

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Cu（OAc）2 / TEMPO / Et2NH催化的苄醇和烯丙基醇的选择性好氧氧化

在有机合成中，在不影响饱和醇的情况下，将苄基和烯丙基醇选择性氧化成其相应的醛/酮衍生物仍然是一项艰巨的努力。各种金属络合物，特别是在TEMPO存在下的铜络合物，在有氧条件下经常用于这种转化，但是它们对烯丙基和苄基醇没有选择性。很少研究在不存在配体的情况下使用铜盐氧化醇的方法，只是用CuCl / TEMPO催化的铜盐在使用CuCl ₂时已注意到氯化物的抑制作用和选择性氧化的缺乏。在此，我们报告一个Cu（OAc）₂在Et ₂ NH存在下催化和TEMPO介导的苄醇和烯丙基醇的选择性好氧氧化为醛/酮。该方法避免了在Cu（II）/（I）络合物/ TEMPO催化的氧化反应情况下的催化剂的预合成，需要低的催化剂负载量，使用便宜的铜盐，并且对苄基和烯丙基醇的氧化具有出色的选择性。