Nitroalkenes as Latent
1,2-Biselectrophiles –
A Multicatalytic Approach for the Synthesis of 1,4-Diketones and Their
Application in a Four-Step One-Pot Reaction to Polysubstituted Pyrroles
posted on 2017-06-23, 00:00authored byPatrick
J. W. Fuchs, Kirsten Zeitler
An NHC-catalyzed
nitro-Stetter/elimination/Stetter reaction
sequence employs nitroalkenes as latent 1,2-dication synthons providing
a novel access to highly useful symmetrical and unsymmetrical 2-aryl
substituted 1,4-diketone building blocks from commercially available
aldehyde precursors. For less activated (aliphatic) aldehydes, a cooperative
catalytic strategy has been developed via the merger of NHC and H-bonding
catalysis. To further showcase the versatility of our approach, a
great variety of these unprecedented 1,4-diketones are used to efficiently
synthesize polysubstituted pyrrolesincluding those with hetaryl
substituentsin good to excellent yields in a multicatalytic
metal-free, four-step one-pot cascade reaction under mild, yet robust,
conditions.