Isolation and characterization of a lithiated pyridine – aggregation in the solid state and in solution

Abstract

The synthesis, isolation and characterization of the pyridyllithium compound 4-Li-2,6-Mes2py is reported. The crystal structure determination revealed a dimer in the solid state. In solution the pyridyllithium was identified as a monomer.

Electronic Modification of a Sterically Demanding Anionic Pyridine Ligand

“…The same borate group has already been successfully introduced to the backbone of NHCs to give the respective anionic NHCs [16] . The addition of B{3,5‐(CF 3 ) 2 ‐C 6 H 3 } 3 to freshly prepared 4‐Li‐2,6‐Mes 2 py [17] afforded [ 1 F ] − as its lithium salt in 74 % isolated yield (Scheme 4).…”

Carbon‐metalated triazines and tetrazines: Synthesis and reactivity

“…Addition of alkyl-, aryl-, and silyl-lithiums to the sterically hindered ortho-di-tert-butyl azolo [1,2,4]triazine 142 (R 1 = t-Bu) was investigated as a route for the generation of a series of highly reactive (3,4-di-tert-butyl-8-methyl-1-substituted-1,4-dihydropyrazolo [5,1-c] [1,2,4]triazin-4-yl) lithiums 143 (Scheme 30). [47] The latter were proved to be ambident nucleophiles.…”

“…Treatment of certain N(1)-trifluoroacylated 3-tertbutyl-1,4-dihydropyrazolo [5,1-c] [1,2,4]triazines 154 with lithium diisopropylamide in THF led to an unexpected rearrangement with formation of 4-tert-butyl-2-perfluoroalkyl-1,4-dihydropyrazolo [1,5-a] [1,3,5]triazine-4-carboxylic acid derivatives 156 in high yields already at <−70 C (Scheme 32). [49] Further heating to ca.…”

“…For example, first X-ray structure of a sp 2 -C-lithiated derivative (namely, 4-lithio-2,6-dimesitylpyridine) was obtained only in 2020. [4] Synthetic applications of the metalated pyridines, pyrimidines, pyrazines, and pyridazines have been extensively studied and reviewed. [3,[5][6][7] The high lability of the triazine and tetrazine heterocyclic cores toward the nucleophilic attack makes metalation of these compounds even more difficult.…”