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|Type:||Artigo de periódico|
|Title:||Ruthenium-catalyzed Reduction Of Racemic Tricarbonyl(η6-aryl Ketone)chromium Complexes Using Transfer Hydrogenation: A Simple Alternative To The Resolution Of Planar Chiral Organometallics|
|Abstract:||Racemic planar chiral (η6-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(η6- benzene)]2 and (-)-ephedrine, resulted in optically active syn-(R,S)-(η6-aryl alcohol)Cr(CO)3 and (R)-(η6-aryl ketone)Cr(CO)3 compounds in 31-97% ee. Reduction of racemic (η6-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)-(η6-thiochroman-4-ol)Cr(CO)3 and (S)-(η6-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 non-rigid acetophenone, propriophenone and their tricarbonylchromium complexes resulted in moderate to low ee. © 2005 Elsevier B.V. All rights reserved.|
|Appears in Collections:||Unicamp - Artigos e Outros Documentos|
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