Palladium‐Catalyzed Oxidative Cycloaddition through CH/NH Activation: Access to Benzazepines

Abstract

Rings beget rings: Benzazepines, well‐known structural design elements in medicinal chemistry, are readily prepared by a one‐pot palladium‐catalyzed oxidative cycloaddition of isatins with various alkynes.

Dehydrogenative Heck Annelations of Internal Alkynes

“…57 The first step of such annelations would be the palladation of the nitrogen atom to afford 16A (Scheme 16). Then, the reaction would occur with two molecules of the alkyne as already shown in Scheme 6, the regeneration of the palladium(II) catalyst being assumed by silver acetate.…”

Synthesis of Azepine Derivatives by Silver‐Catalyzed [5+2] Cycloaddition of γ‐Amino Ketones with Alkynes

“…[1][2][3][4][5] This process is most frequently used to prepare five-and six-membered ring systems. [1][2][3][4][5] This process is most frequently used to prepare five-and six-membered ring systems.…”

“…[1][2][3][4][5] This process is most frequently used to prepare five-and six-membered ring systems. [1][2][3][4][5] The difficulties of such an approach are likely caused by a combination of entropic factors and the presence of non-bonding interactions in the transition state. [1][2][3][4][5] The difficulties of such an approach are likely caused by a combination of entropic factors and the presence of non-bonding interactions in the transition state.…”

“…[1] However, approaches using a cycloaddition strategy for constructing seven-membered ring systems, particularly seven-membered heterocyclic ring systems, are much less abundant. [1][2][3][4][5] Particular focus has been put on the synthesis of azepine derivatives, [4,5] because these are important skeletal units that are found in numerous natural products and in compounds with important chemical, biological, and medicinal properties ( Figure 1). Despite the impressive challenges in this field, the continuing identification of bioactive natural products that contain a seven-membered ring has led to considerable efforts to establish valuable cycloaddition methods for their construction.…”

“…[1][2][3][4][5] The difficulties of such an approach are likely caused by a combination of entropic factors and the presence of non-bonding interactions in the transition state. [6] Among the reported cycloaddition [1][2][3][4][5] and classical approaches [7] toward azepine derivatives, [5+2] cycloaddition reactions with alkynes are particularly straightforward and highly selective; however, these transformations are quite rare and are restricted to electron-poor alkynes. [1][2][3][4][5] Particular focus has been put on the synthesis of azepine derivatives, [4,5] because these are important skeletal units that are found in numerous natural products and in compounds with important chemical, biological, and medicinal properties ( Figure 1).…”