77332-76-4Relevant academic research and scientific papers
Unusual t-BuLi induced ortholithiation versus halogen-lithium exchange in bromopyridines: Two alternative strategies for functionalization
Pierrat, Philippe,Gros, Philippe,Fort, Yves
, p. 2319 - 2322 (2007/10/03)
The reaction of lithiating agents with various 3-bromopyridines has been investigated. An unprecedented selectivity was observed with t-BuLi, which effected a clean lithiation at C-4. With 3-bromo and 2-chloro-3-bromo pyridines, the ortholithiation-exchange ratio was strongly electrophile and addition order dependent while 2-chloro-5-bromopyridine always gave exclusive C-4 substitution.
Lithiation of 2-chloro- and 2-methoxypyridine with lithium dialkylamides: Initial ortho-direction or subsequent lithium ortho-stabilization?
Gros, Philippe,Choppin, Sabine,Fort, Yves
, p. 2243 - 2247 (2007/10/03)
The lithiation pathway of 2-chloro and 2-methoxypyridine with LDA and LTMP has been investigated using deuterated probes. The availability of both H-6 and H-3 protons on the pyridine nucleus was found to be critical to ensure complete C-3 lithiation. We thus concluded that the C-3 lithiation was not a straightforward process. A mechanism involving precomplexation of lithium dialkylamides near the H-6 proton and formation of a 3,6-dilithio pyridine intermediate is proposed.
REGIOSELECTIVE ORTHO-LITHIATION OF HALOPYRIDINES. SYNTHESES OF ORTHO-DISUBSTITUTED PYRIDINES AND A CONVENIENT GENERATION OF 3,4-PYRIDYNE
Gribble, Gordon W.,Saulnier, Mark G.
, p. 151 - 169 (2007/10/02)
The regioselective ortho-lithiation of 3-chloro- (4), 3-fluoro- (7), 3-bromo- (10), 2-chloro- (22), and 4-chloropyridine (25) with lithium diisopropylamide affords, after quenching with various electrophiles, the corresponding ortho-disubstituted pyridine
Le phenyl-lithium: nouvel agent de metallation du cycle pyridinique
Mallet, Marc
, p. 49 - 56 (2007/10/02)
Nucleophilic addition was the sole reaction of phenyl-lithium with a pyridinic ring; now the novel catalysed metallation, with phenyl-lithium, of many substituted pyridine compounds giving various derivatives in high yields with many different reagents, has been achieved.
Improved Synthesis of 2,3-Disubstituted Pyridines by Metallation of 2-Chloropyridine: a Convenient Route to Fused Polyheterocycles
Trecourt, Francois,Marsais, Francis,Guengoer, Timur,Queguiner, Guy
, p. 2409 - 2415 (2007/10/02)
Chemoselective directed metallation of 2-chloropyridine allows the synthesis of 2-substituted 3-carbonylated pyridines, advantage being taken of the metallation ortho-directing effect of the halogen, as well as its reactivity towards nucleophiles.Thus (2-chloro-, 2-methoxy-, and 2-amino-3-pyridyl)-ethanones and -arylmethanones as well as carbaldehydes have been prepared.Some of these ortho-disubstituted intermediates have been readily cyclized to fused polyheterocycles such as naphthiridines and aza-analoges of coumarins, xanthones, and acridones.
Regioselective ortho lithiation of halopyridines
Gribble, Gordon W.,Saulnier, Mark G.
, p. 4137 - 4140 (2007/10/02)
Regioselective ortho lithiation of 2-, 3-, and 4-halopyridines is achieved with lithium diisopropylamide (-78°, tetrahydrofuran) to afford, upon quenching with electrophilic reagents, 2,3- and 3,4-disubstituted pyridines in good to excellent yield.
