Control of the Reaction of n‐Butyllithium with Benzo[b]tellurophene by the Solvent—Either Metalation or Tellurium–Lithium Exchange To Give an Interesting Lithiostyryllithium

Abstract

yield > 90%) [I,]

Versatile telluracycle synthesis via the sequential electrophilic telluration of C(sp2)–Zn and C(sp2)–H bonds

“…The reaction chemistry of benzotellurophene and n -BuLi 21 enabled the further transformations of the 3-methylbenzotellurophenes 3al–3cl ( Scheme 4 ). Thus, these benzotellurophenes were amenable to C2-lithiation using n -BuLi in THF, and the resulting 2-lithiobenzotellurophenes were readily transformed into 2-borylated benzotellurophenes 4a–4c .…”

“… 22 This luminescence was found to have a short lifetime in the order of ns (see the ESI † ), and the relevance of this to the phosphorescent nature of Rivard’s borylated (benzo)tellurophenes in the solid state 4 remains to be explored. A treatment of 3bl with excess n -BuLi in hexane resulted in double tellurium–lithium exchange, 21 and subsequent trapping with Bu 2 SnCl 2 furnished benzostannole 5 in 60% yield. The success of this conversion would hold promise for the use of benzotellurophenes as versatile precursors for different benzoheteroles, 10 such as benzosilole 23 and benzophosphole.…”

The Role of Ate Complexes in the Lithium-Sulfur, Lithium-Selenium and Lithium-Tellurium Exchange Reactions

“…There was some reason to be concerned, since, in contrast to most selenides, which undergo Li/Se exchange on treatment with alkyllithium reagents, selenophene [16] and benzoselenophene [17] are instead metallated by BuLi. Even dibenzoselenophene [18a] and benzotellurophene [12] can be metallated cleanly under appropriate conditions. Thus, these systems, rather than being activated toward Li/M exchange, show an unusual resistance to nucleophilic attack at the heteroatom, perhaps as a result of aromatic stabilization of the heterocyclic ring.…”

“…Hypervalent ate complexes such as 1 ± 3 have been spectroscopically characterized and are likely intermediates in the degenerate phenyl-phenyl Li/I [7a] [7b] [8] [9], Li/Te [7b] [7c] [10a], and Li/Sn [7d] [11] [12] exchange reactions. Ate complexes of third-and even second-row metalloids Se, P, and Si can be detected in favorable structures, e.g., when the aryl groups are heavily substituted with electronegative halogen atoms (4, see [10b]) or when o,o'-biphenyldiyl ligands are present (5, see [13] and 6, see [14a]).…”

1,5-Dilithiated Synthetic Building Block, (E)-o-(2′-Lithiovinyl)benzyllithium, by Tellurium-Lithium Exchange of Isotellurochromene

“…Recently, tellurium-lithium exchange has been employed in both the fields of organic synthetic chemistry 6 and heterocyclic chemistry. 7 As we have previously described the synthesis of the isotellurochromenes as the precursors for the preparation of the 2-benzotelluropyrylium salts, 8 this prompted us to examine the tellurium-lithium exchange of isotellurochromenes and its use for the preparation of (E)-o-(2'lithiovinyl)benzyllithium.…”