Cesium carbonate-promoted synthesis of aryl methyl sulfides using: S -methylisothiourea sulfate under transition-metal-free conditions
In the presence of cesium carbonate, an efficient synthesis of aryl methyl sulfides by the reactions of aryl halides with commercially available S-methylisothiourea sulfate is developed. This odourless and highly crystalline solid can be used as the subst
A study on the BF3 directed lithiation of 3-chloro- and 3-bromopyridine
The BF3-directed lithiation of 3-chloro- and 3-bromopyridine (1a and 1b, respectively) has been investigated. The reactions of 3-chloro- or 3-bromopyridine-BF3 adduct with LDA (1.3/1.1 equiv) followed by quenching with benzaldehyde or iodine exclusively gave the C-2 substituted products. However, when 2.2 equiv of LDA and dimethyl disulfide was used, a C-6 substituted product was obtained. Dilithiation of 1a and 1b has been studied with and without the involvement of BF3 complexation. The role of Lia?F(BF3) interactions has been investigated by experimental and DFT calculations.
Dhau, Jaspreet S.,Singh, Amritpal,Kasetti, Yoganjaneyulu,Bhatia, Sonam,Bharatam, Parsad V.,Brand?o, Paula,Félix, Vítor,Singh, Kamal N.
p. 10284 - 10291
(2013/11/19)
LIGAND EXCHANGE AND LIGAND COUPLING VIA THE ?-SULFURANE INTERMEDIATE IN THE REACTION OF ALKYL 2-PYRIDYL SULFOXIDE WITH GRIGNARD REAGENTS: CONVENIENT PREPARATION OF 2,2'-BIPYRIDINES
The reaction between methyl 2-pyridyl sulfoxide (1) with Grignard reagents afforded 2,2'-bipyridine (2) in moderate yield.The reaction is considered to involve initial ligand exchange to generate 2-pyridylmagnesium halide which in the subsequent step attacks the original sulfoxide to form the ?-sulfurane that undergoes ligand coupling to afford 2.The reaction of t-butyl-2-pyridyl sulfoxide (3) with C6H5MgBr, however, gave only 2-phenylpyridine (4).This may due to steric hindrance to the initial ligand exchange.Formation of 2 is a convenient process for preparation of 2,2'-bipyridines bearing various substituents.
Oae, Shigeru,Kawai, Tsutomu,Furukawa, Naomichi
p. 123 - 132
(2007/10/02)
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