Direct Organocatalytic Oxo‐Metathesis, a trans‐Selective Carbocation‐Catalyzed Olefination of Aldehydes. Issue 8 (5th February 2015)

• Record Type: Journal Article
• Authors: Veluru Ramesh Naidu, ; Bah, Juho; Franzén, Johan
• Is Part Of: European journal of organic chemistry. Issue 8(2015)
• Page Start: 1834
• Page End: 1839
• Publication Date: 2015-02-05
• Subjects: Organocatalysis -- Metathesis -- Carbocations -- Ketones -- Alkenes; Chemistry, Organic -- Periodicals; Organic compounds -- Synthesis -- Periodicals; Bioorganic chemistry -- Periodicals; Chemistry, Physical organic -- Periodicals; 547
• DOI: 10.1002/ejoc.201403651
• Languages: English
• ISSNs: 1434-193X

Abstract

Abstract: A direct organocatalytic carbonyl/olefin oxo‐metathesis has been developed. The reaction is catalyzed by trityl tetrafluoroborate (TrBF4 ) and utilizes unactivated alkenes for the olefination of aromatic aldehydes to give trans β‐alkylstyrenes in yields of 44–85 % with only acetone as the byproduct. The pronounced Lewis acidity of the carbocation results in unusual reactivity that is proposed to catalyze a stepwise [2+2] cycloaddition to give an oxetane intermediate. Fragmentation of the latter in a formal retro [2+2] reaction gives the oxo‐metathesis product. Abstract : A new partner in the metathesis dance: Trityl tetrafluoroborate (TrBF4 ) catalyzes the direct oxo‐metathesis of aldehydes and unactivated olefins to give β‐alkylstyrene derivatives and acetone through an unusual metal‐free formal [2+2]/retro [2+2] reaction sequence.