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|Type:||Artigo de periódico|
|Title:||Ruthenium-catalyzed reduction of racemic tricarbonyl(eta(6)-aryl ketone)chromium complexes using transfer hydrogenation: A simple alternative to the resolution of planar chiral organometallics|
|Abstract:||Racemic planar chiral (eta(6)-aryl ketone)Cr(CO)(3) complexes (aryl ketone = 1-indanone, 1-tetralone, 4-chromanone and thiochroman-4-one) were prepared by refluxing the aryl ketone with Cr(CO)(6) in a 10: 1 mixture of dibutyl ether and THF. The reductions of the organometallic ketones by transfer hydrogenation in 2-propanol containing KOH and the catalyst precursor, generated from [RuCl2(eta(6)-benzene)](2) and (-)-cphedrine, resulted in optically active syn-(R,S)-(eta(6)-aryl alcohol)Cr(CO)(3) and (R)-(eta(6)-aryl ketone)Cr(CO)(3) compounds in 31-97% ee. Reduction of racemic (eta(6)-thiochroman-4-one)Cr(CO)(3) with the catalyst precursor generated from (+)-norephedrine, instead of (-)-ephedrine, inverted the configuration of the products obtained. Syn-(S,R)-(eta(6)-thiochroman-4-ol)Cr(CO)(3) and (S)-(eta(6)-thiochroman-4-one)-Cr(CO)(3) were isolated in 49% and > 95% ee, respectively. The free aryl ketones were reduced using the same conditions as their respective chromium complexes, giving aryl alcohols in high ee (> 95%). Reactions of nonrigid acetophenone, propriophenone and their tricarbonylchromium complexes resulted in moderate to low ee. (c) 2005 Elsevier B.V. All rights reserved.|
|Editor:||Elsevier Science Sa|
|Appears in Collections:||Unicamp - Artigos e Outros Documentos|
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