A benzannulation protocol to prepare substituted aryl amines using a Michael-aldol reaction of beta-keto sulfones.
A practical benzannulation method to prepare variously substituted aryl amines and sulfides was developed. The approach involves a Michael-aldol reaction of beta-keto sulfones with enones followed by a subsequent condensation of the initial adduct with various amines. The base-induced Michael-aldol cascade proceeds smoothly with a number of different beta-keto sulfones, affording the adducts as single diastereomers. Heating the resulting Michael-aldol product with an amine in toluene at 120 degrees C results in the formation of a transient enamine, which then undergoes loss of phenyl sulfenic acid to furnish the aromatized amine in good yield. A related reaction also occurred when the Michael-aldol product was heated with thiols or alcohols, giving rise to aryl-substituted sulfides or ethers.
Department of Chemistry, Emory University, Atlanta, Georgia 30322, USA.
Sezgin
S
Kiren
Albert
A
Padwa
D000447:Aldehydes / Q000737:chemistry*; D000588:Amines / Q000138:chemical synthesis / Q000737:chemistry*; D003500:Cyclization; D007659:Ketones / Q000737:chemistry*; D015394:Molecular Structure; D013450:Sulfones / Q000737:chemistry*
D000447:Aldehydes; D000588:Amines; D007659:Ketones; D013450:Sulfones; C116609:3-hydroxybutanal