Phthalimidoketo aldehyde

The method is limited to activated halides which are stable to aUtoxide bases and aqueous acids. According to the discoverer, the Krdhnke oxidation is inferior to the Sommelet reaction for benzyl halides, especially those bearing electron-withdrawing groups, such as nitro. Some representative examples are shown in Scheme 6 and equations (6)-<12). As can be seen, the Krbhnke oxidation is an excellent method for the preparation of heterocyclic aldehydes which would otherwise be difficult to synthesize. The preparations of a phthalimidoketo aldehyde (equation 11) and benzene-l,3,S-tricarbalde-hyde (equation 12) are also noteworthy. 

---