A Nonoxidative Sequence for the Preparation of 1,2-Diketone Derivatives Using Aldehyde and Organometallic Building Blocks
作者:Gwyneth L. Pudner、Isabela Camp、Jonathan R. Scheerer
DOI:10.1021/acs.joc.2c00439
日期:2022.6.17
investigates a synthetic sequence for the preparation of 1,2-diketone products. The sequence avoids oxidative conditions and instead employs reliable transformations including the Horner–Wadsworth–Emmons and addition of Grignard reagents to N-methyl-N-methoxy (Weinreb) amide intermediates. The reaction sequence is suitable for the synthesis of nonsymmetric aliphatic and aryl substituted derivatives.
Methyl (Z)-α-methoxyacrylates are generated in good yields by a mild, stereospecific two-carbonhomologation of a wide variety of aldehydes utilizing commercial methyl 2,2-dichloro-2-methoxyacetate and CrCl2 under Barbier conditions at room temperature. A rational mechanism based upon a Reformatsky-type addition pathway or an in situ generated (E)-trioxo-chromium vinylidene carbenoid is proposed.