Pd-Catalyzed Reactions of o-Diiodoarenes with Alkynes for Aromatic Ring Extension

Abstract

[reaction: see text] A new and efficient palladium-catalyzed reaction of o-diiodoarenes with internal alkynes produces naphthalenes or anthracenes in good to excellent yields. This procedure provides a simple, catalytic, and straightforward ring-extension method for constructing substituted polycyclic aromatic compounds.

Synthesis, Structures, and Physical Properties of Benzo[k]fluoranthene‐Based Linear Acenes

“…[23] The diynes 8 g and 8 h generated the desired cycloadducts 4, accompanied by the byproducts 4' and the fluoranthenes 23.…”

“…[21] Accordingly, stabilized benzynes or pre-benzynes are suitable starting materials in the protocol designed here. Fortunately, in the presence of Pd catalysts, iodobenzenes [22] and 1,2-diiodobenzenes [23] can be formally treated as pre-arynes, which have been utilized in the synthesis of highly substituted naphthalenes through cycloaddition with two alkyne units. In the light of these metal-catalyzed protocols, the target molecules 4 and 5 were observed to be obtainable through Pd-catalyzed cycloadditions between 1,8-diethynylnaphthalenes 8 and either iodobenzene (6 a) or 2,3-diiodonaphthalene (7 a), respectively.…”

Dehydrogenative Heck Annelations of Internal Alkynes

“…+ Pd(OAc) 2 (0.1 equiv) PivOH (1 equiv) n-Bu 4 NBr (0.5 equiv) K 2 ladium(II) into a nitrogen-hydrogen bond, and 9F resulting from the coordination of both alkyne and aniline to the palladium atom, as alternative intermediates leading to 9C (Scheme 9, paths c and d).…”

“…55 These additives could act as ligands, leading to more active palladium species. 47 + Pd(OAc) 2 Equation 41 5…”

“…1 For the coupling with dialkylated alkynes, Takahashi's research team proposed the use of o-diiodoarenes (ArX 2 ) (Equation 2). 2 A variety of polycyclic systems have been synthesized using such methods. 3 With 2-iodoaniline or 2-iodophenol as arylating agent, Larock and co-workers carried out the synthesis of either 2,3-disubstituted indoles (Equation 3) or 2,3-disubstituted benzofurans (Equation 4).…”