## 3 Sequences Based upon Amination  
Initiated by [PERSON] and [PERSON] in the past two decades Pd-catalyzed carbon-heteroatom bond forming processes have considerably fertilized the field of heterocyclization and the catalyst sources are often identical with those for carbon-carbon bond forming processes [89; 90; 91; 92; 93]. Several intriguing one-pot sequences have been developed on this conceptual basis furnishing specific substitution patterns on classical and novel heterocyclic core structures. A prominent example of a two-component sequential catalysis is the intermolecular-intramolecular Buchwald-Hartwig double amination reported by [PERSON] and coworkers [94]. The method uses 2,2'-dihalobiphenyls and primary amines for the synthesis of multisubstituted carbazoles **22** that possess intriguing optical properties (Scheme 14). The methodology has then been applied to the synthesis of different compound classes, for instance to the synthesis of diazacarbazoles [95], ladder-type \(\pi\)-conjugated heteroacenes [96], dithienopyrroles [97; 98; 99], and to the synthesis of the phenothiazze backbone of promazines [100]. **Scheme 14. ** Sequentially Pd-catalyzed intermolecular intramolecular Buchwald-Hartwig double amination sequence to access multisubstituted carbazoles **22**. The method has also been employed in the synthesis of dithienothiazines **23** that possess interesting electronic properties involving reversible oxidation and can therefore be regarded as new donors for functional \(\pi\)-systems (Scheme 15, Table 6) [101; 102]. **Scheme 15. ** Sequentially Pd-catalyzed intermolecular intramolecular Buchwald-Hartwig double amination sequence to access dithienothiazines **23**. [PERSON] and [PERSON] reported an assisted tandem catalysis involving an intramolecular palladium-catalyzed Buchwald-Hartwig amination and intermolecular Suzuki-Miyaura coupling [103]. By the use of _gem_-dihalovinyls as starting materials, 2-functionalized indoles **24** could be accessed using various organoboron compounds as coupling partners in the Suzuki-Miyaura-coupling (Scheme 16, Table 7). The developed method has been further elaborated by the same group to provide access to substituted azaindoles and thienopyrroles, respectively [104, 105, 106]. If the _gem_-dihalovinyl group was placed _ortho_ to the amino group in amino-pyridines or anlines, the catalytic system performed a Buchwald-Hartwig amination followed by subsequent Suzuki- [104, 105] or Heck-coupling [106], respectively. In a related fashion, the [PERSON] group could employ the same concept for a thioanellation furnishing 2-substituted benzothiophenes by sequentially Pd-catalyzed CS- and CC-bond formation [107]. Furthermore, the developed Pd-catalyzed Buchwald-Hartwig amination Suzuki-coupling methodology has been applied to the synthesis of kinase insert domain-containing receptor (KDR) kinase inhibitors, which pose as promising compounds in anti-tumor therapy [105]. \begin{table}
\begin{tabular}{c c c} \hline
**Entry** & **Amine** & **Dithienothiazines 23 (Yield)** \\
1 & R\({}^{1}\) = Ph & \\  & & \\  
**Scheme 16. ** Sequentially Pd-catalyzed Buchwald-Hartwig amination Suzuki-Miyaura coupling sequence for the synthesis of 2-functionalized indoles **24**. **Table 7.** Selected 2-functionalized indoles **24** via sequentially Pd-catalyzed Buchwald-Hartwig amination Suzuki-Miyaura-coupling sequence.