Efficient Ruthenium‐Catalyzed Transfer Hydrogenation/Hydrogenation of 1,3‐Cycloalkanediones to 1,3‐Cycloalkanediols Using Microwave Heating.

Abstract

Hydrogenation O 0220 Efficient Ruthenium-Catalyzed Transfer Hydrogenation/Hydrogenation of 1,3-Cycloalkanediones to 1,3-Cycloalkanediols Using Microwave Heating. -(LEIJONDAHL, K.; FRANSSON, A.-B. L.; BAECKVALL*, J.-E.; J. Org. Chem. 71 (2006) 22, 8622-8625; Dep. Org. Chem., Arrhenius Lab., Univ. Stockholm, S-106 91 Stockholm, Swed.; Eng.) -Jannicke 10-049

The Golden Age of Transfer Hydrogenation

“…The well-established family of robust Noyori catalysts is very effective in terms of activity and stereoselectivity for ATH using either 2-PrOH or formic acid typically as the hydrogen source and for AH . This robustness of the Noyori catalysts promotes numerous applications in total synthesis and synthetic methodology − as well as the development of many structural variations of these catalysts such as the introduction of the N - R -sulfonyl fragment, the sulfonamide moiety, the η 6 -arene ligand, or the diamine unit. , For example, in 1999 Ikariya’s group reported that a Noyori catalyst efficiently promoted the asymmetric reduction of 1,2-diphenylethane-1,2-dione (benzyl) with a substrate/catalyst molar ratio of 1000–2000 in mixed solvents consisting of formic acid and triethylamine, giving a series of ( R , R )-hydrobenzoin 18 quantitatively with high diastereomeric (97% de) and enantiomeric purities (>99% ee) (Scheme ). As chiral 1,2-diols, the ( R , R )-hydrobenzoins 18 are important building blocks in stereoselective organic syntheses as well as chiral ligands.…”

A family of novel cationic ruthenium pincer complexes: Synthesis, characterization and catalytic activity in the transfer hydrogenation of ketones

“…Recently, the Ru(II) complexes bearing planar tridentate N 3 ligands and unsymmetrical planar tridentate ligands have been successfully developed and explored to construct the effective catalyst systems for the transfer hydrogenation of ketones [5][6][7][8][9][10]. In the study of the transfer hydrogenation mechanism, several ruthenium hydride complexes are considered as active species [11][12][13][14][15][16][17][18], but some ruthenium hydride complexes, such as RuHCl(PPh 3 ) 3 [11], are not the really active species. For the Ru(II) complexes bearing planar tridentate N 3 ligands, although some researchers regard the ruthenium hydride complexes as the real active species in the transfer hydrogenation of ketones [5][6][7][8][9][10], no ruthenium hydride complex has been isolated.…”

“…Both showed low activities. Complex 2 exhibited a high transfer hydrogenation activity for pyridyl ketones (entries [15][16][17].…”