PDC是一种广泛应用的温和型中性氧化剂。与PCC 比较，氧化能力较弱，没有酸性。与MnO2 比较，氧化能力较强，制备方便。PDC 的氧化能力和反应溶剂有关，PDC用DMF当溶剂可以将伯醇氧化为酸，而在 CH2Cl2 中则将伯醇、仲醇、苄醇和烯丙基醇稳定地转变为相应的醛酮化合物。通过选用不同的溶剂，PDC 许多时候可以取代 PCC 和 MnO2 在有机合成中的许多功能。另外PDC还可将环状半缩醛氧化成为相应的内酯或者内酰胺，在叔丁基过氧化氢帮助下将苄位或烯丙位亚甲基氧化为羰基化合物。将吡啶加入到三氧化铬的水溶液中有亮黄色的PDC固体生成，PDC溶于有机溶剂，在空气中室温下，易于储存和操作。在二氯甲烷的悬浮溶液中可以将醇氧化为醛酮（ 与PCC氧化类似，惰性气体保护避免接触空气中的水。）。另外3Å分子筛，HOAc，PPTS，PTFA，Ac2O可以加快PDC的氧化速度。反应结束可以用亚硫酸钠快速淬灭反应。单单只是用PCC或PDC的话，伴随着反应的进行，会生成出黑褐色油状残渣。生成物被这些残渣所包裹，导致产率降低。像反应溶液中加入适量硅藻土，硅胶或者是分子筛，能够改善这种情况。氧化的一般操作步骤：Approximately,1.1–7 equivalents of solid PDC are added over a ca. 0.01–0.30 M solution of thealcohol in dry DCM. The resulting suspension is stirred at roomtemperature. Approximately, 0.5–4 g of activated MS-preferably finely ground 3ÅMS-per mmol of alcohol can be added in order to accelerate the oxidation. Thereaction can also be accelerated by the addition of ca. 0.9–4 equivalents of dryAcOH or 0.75–12 equivalents of acetic anhydride. The simultaneous use ofmolecular sieves and an organic acid has a synergistic accelerating effect. Theaddition of ca. 0.5–2.50 g of Celite or Florisil (magnesium silicate) per mmol of alcohol canfacilitate the work-up. Celite or Florisil can be added either at the beginningof the oxidation or ca. 30 min before the work-up. Two alternative work-ups canbe carried out.Work-upA:The most common workup. Et2Ois added and the precipitate is decanted and washed with ether. The collectedorganic phases are filtered through a pad of Celite, silica or Florisil.Alternatively, decanting the precipitate can be avoided and the mixture,resulting from the addition of ether, can be directly filtered through a pad ofsilica, Celite or Florisil. When the reaction is carried out under diluteconditions, the addition of diethyl ether can be avoided. The organic phase isconcentrated giving a residue that may need chromatographic purification. Whenthe reaction iscarried out in the presence of addedCelite or Florisil, a similar work-up is made in which the Celite or Florisilis filtered.Work-upB:Et2O is added and theresulting mixture is washed with aqueous phases. The aqueous phases used canbe: plain water, aqueous saturated NaHCO3 solution, diluted HCl or brine.The collected organic phases are dried (MgSO4 or Na2SO4)and concentrated, giving a residue that may need chromatographic purification.反应实例
【Terpstra, J. W.; Van Leusen, A. M. J. Org. Chem.1986, 51, 230–208】
