Catalytic Enantioselective Synthesis of Chiral Tetraphenylenes: Consecutive Inter‐ and Intramolecular Cycloadditions of Two Triynes

Abstract

Triynes having a phenylene‐bridged 1,5‐diyne moiety were transformed into substituted tetraphenylenes by the title sequence. A cationic Rh–ligand species catalyzed this highly enantioselective reaction. This protocol is a new and easy approach to the construction of the tetraphenylene skeleton and enables an efficient asymmetric synthesis (see scheme; R=H; Z=NTs, C(CO2Me)2, O).

Enantioselective construction of new chiral cyclic scaffolds using [2 + 2 + 2] cycloaddition

“…1) [13]. Thus, we tried to develop the first highly enantioselective synthesis of chiral tetraphenylenes using a new approach [14]. …”

Iridium-catalyzed intramolecular [4 + 2] cycloadditions of alkynyl halides

“…Many different transition-metal catalysts have been described for these types of reactions, employing a variety of different metals including Ni [29], Co [30], Rh [31–34], Pd [35–36] and Ir [26–27]. Much research has been done on intramolecular TMC [4 + 2] cycloadditions of a variety of diene-tethered alkynes to form substituted bicyclic products 2 (Scheme 1); however, the majority of these examples demonstrate Y = alkyl or aryl, and R = methyl.…”

Synthesis of tetraphenylene derivatives and their recent advances

“…In 2009, Shibata developed a catalytic and enantioselective method for the synthesis of chiral tetraphenylenes based on a [2 + 2 + 2] cycloaddition of triynes [60][61][62]. This approach gave the target tetraphenylene derivatives (96) in good yields (45-93%) with excellent enantioselectivities (up to 99%).…”