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DOI: 10.1055/s-2008-1042698
Rhodium-Catalyzed Conjugate Addition of Boronic Acids to Vinyl 2-Pyridyl Sulfones
Contributor(s):Mark Lautens, Valentina AureggiUniversitad Autonoma de Madrid, Spain
Enantioselective Synthesis of Chiral Sulfones by Rh-Catalyzed Asymmetric Addition of Boronic Acids to α,β-Unsaturated 2-Pyridyl Sulfones
J. Org. Chem. 2007, 72: 9924-9935
Publication History
Publication Date:
21 February 2008 (online)
Key words
chiral sulfones - organoboronic acids - rhodium
Significance
Only a few examples of Rh-catalyzed addition of α,β-unsaturated sulfones with boronic acids are reported in the literature, despite the utility of sulfones in organic synthesis. This work describes a new efficient method for the Rh-catalyzed asymmetric conjugate addition of boronic acids to β-substituted vinyl 2-pyridyl sulfones. The corresponding sulfonylated products are obtained in good yields and enantioselectivities up to 92% ee.
Comment
The conjugate addition of alkyl and aryl boronic acids to cis and trans β-substituted vinyl sulfones using the [Rh(acac)(C2H4)2]/Chiraphos catalyst system shows a broad scope and provides the corresponding products in good yields and moderate to high enantioselectivities. The 2-pyridyl sulfones are crucial, while simple vinyl sulfones are inert under the reaction conditions. In addition the authors show the synthetic application of the conjugate addition products as versatile intermediates for the preparation of allylic derivatives (by Julia-Kocienski olefination), or β-substituted ketones or esters (by an acylation-desulfonylation sequence.