Supramolecularly Regulated Ligands for Asymmetric Hydroformylations and Hydrogenations

Journal Reference

Chemistry. 2015 Aug 3;21(32):11417-26.

Vidal-Ferran A1,2, Mon I3, Bauzá A4, Frontera A4, Rovira L3.

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1. Institute of Chemical Research of Catalonia (ICIQ), Avgda. Països Catalans 16, 43007 Tarragona (Spain), Fax: (+34) 977920228. [email protected].
2. Catalan Institution for Research and Advanced Studies (ICREA), Passeig Lluís Companys 23, 08010 Barcelona (Spain). [email protected].
3. Institute of Chemical Research of Catalonia (ICIQ), Avgda. Països Catalans 16, 43007 Tarragona (Spain), Fax: (+34) 977920228.
4. Departament de Química, Universitat de les Illes Balears (UIB), Cra. de Valldemossa, km 7.5. Palma, 07122 Palma de Mallorca (Spain).

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Abstract

Herein we report the use of polyether binders as regulation agents (RAs) to enhance the enantioselectivity of rhodium-catalyzed transformations. For reactions of diverse substrates mediated by rhodium complexes of the α,ω-bisphosphite-polyether ligands 1-5,a-d, the enantiomeric excess (ee) of hydroformylations was increased by up to 82 % (substrate: vinyl benzoate, 96 % ee), and the ee value of hydrogenations was increased by up to 5 % (substrate: N-(1-(naphthalene-1-yl)vinyl)acetamide, 78 % ee). The ligand design enabled the regulation of enantioselectivity by generation of an array of catalysts that simultaneously preserve the advantages of a privileged structure in asymmetric catalysis and offer geometrically close catalytic sites. The highest enantioselectivities in the hydroformylation of vinyl acetate with ligand 4 b were achieved by using the Rb[B(3,5-(CF3)2 C6 H3)4] (RbBArF) as the RA. The enantioselective hydrogenation of the substrates 10 required the rhodium catalysts derived from bisphosphites 3 a or 4 a, either alone or in combination with different RAs (sodium, cesium, or (R,R)-bis(1-phenylethyl)ammonium salts). This design approach was supported by results from computational studies.

© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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