- 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
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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
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p. 123 - 132
(2007/10/02)
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- Electro-organic Reactions. Part 24. Preparative and Mechanistic Aspects of the Anodic Oxidation of Dithioacetals and 1,3-Dithianes
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Anodic oxidation of the title compounds is a convenient and efficient method for deprotection, i.e. for the regeneration of carbonyl compounds. A detailed investigation of sulphur-containing products confirmed that the initial, 2 F mol-1, products are disulphides which, in aqueous acetonitrile, are oxidised further to alkyl alkane thiosulphinates and the corresponding thiosulphonates.In some cases alkyl polysulphides and N-alkylacetamides are important products.Unsymmetrical dithioacetals are oxidised anodically to the three possible disulphides, i.e. cross-coupling occurs.Unsymmetrical disulphides are similarly oxidised to a complex mixture of symmetrical and unsymmetrical thiosulphinates and thiosulphonates. These results, combined with those of cyclic voltammetric and coulometric experiments, suggest a mechanism in which the key step in carbon-sulphur bond cleavage in the initially formed radical cation.The direction of the cleavage is determined by understandable substituent effects.
- Porter, Quentin N.,Utley, James H. P.,Machion, Pedro D.,Pardini, Vera L.,Schumacher, Paolo R.,Viertler, Hans
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p. 973 - 979
(2007/10/02)
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