Wacker process improvements

The BASF process1026 was developed to use o-xylene exclusively. Most processes, however, such as the Wacker-von Hey den process1027 1028 are capable of operating on both feedstocks or may use a mixture of the two compounds. Fluidized-bed operations were developed in the 1960s (Badger process1029 1030) but have been replaced by improved, more economical fixed-bed processes. The Alusuisse low-air-ratio (LAR) process, for instance, allows the use of a 9.5 1 air o-xylene mixture and achieves an increased catalyst productivity.1031 1032... 

One of the first applications of palladium to indole synthesis was due to Hegedus [12-17], who adapted the known Pd-mediated amination of alkenes [18] to the intramoleclar amination of o-vinyl- or o-allylanilines (Scheme 1, equations 1 and 2). This Wacker-like process involves Pd(II) and can be stoichiometric or catalytic. For an excellent review of the Hegedus indole synthesis, see Johnston [19]. Although it is rarely referred to as such, the Hegedus reaction has found several applications and extensions in indole synthesis (equations 3-5) [20, 21, 23]. The preparation of ethyl indole-2-carboxylates (equation 4) [21] has been improved by McNulty and Keskar [22], and Danheiser synthesized 6- -butyl-l,2-dimethyl-4-hydroxyindole via a... 

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