Knoevenagel/hydrogenation/Robinson annulation sequence

In 2007, Ramachary et al. reported an asymmetric Knoevenagel/hydrogenation/Robinson annulation sequence to obtain Wieland-Miescher ketone 189 [88] (Scheme 2.62). The reaction of 5 equiv of aldehyde 9 with the 1,3-dicarbonyl compounds 186 (with CH acid) and Hantzsch ester 187 under proline catalysis furnished the expected cyclo-hexane-1,3-dione B in good yields. Once the solvent was removed by vacuum pump, the crude reaction mixture was diluted with DMF and treated with methyl vinyl ketone 188 in the presence of (S)-proline (1) furnishing the expected... 

SCHEME 2.62 Synthesis of Wieland-Miescher ketone via Knoevenagel/hydrogenation/Robinson annulation sequence. 

D. B. Ramachary, M. Kishor, J. Org. Chem. 2007, 72, 5056-5068. Organocatalytic sequential one-pot double cascade asymmetric synthesis of Wieland-Miescher ketone analogues from a Knoevenagel/hydrogenation/Robinson annulation sequence scope and apphcations of organocatalytic biomi-metic reductions. 

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See also in sourсe #XX -- [ ]

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