BINOL-Based Ditopic Diphosphite Ligands – Synthesis, Evaluation and Regioselectivity Optimization of Catalytic Hydroformylation by 23 Factorial Design

Author(s): Andreia F. Peixoto, Artur R. Abreu, Ana R. Almeida, Angela Neves, Paulo E. Abreu, Maria J.S.M. Moreno, Juan C. Bayon, Alberto A.C.C. Pais, Mariette M. Pereira

Journal Name: Current Organic Synthesis

Volume 11 , Issue 2 , 2014


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Abstract:

BINOL-based diphosphite ligands containing oxygen or nitrogen heteroatoms are currently a new class of promising ligands for homogeneous catalysis. Herein we present a useful strategy to synthesize ditopic (R)-BINOL-based diphosphites, containing pyridyl or propyl ether bridges between BINOL fragments in high isolated yields (50-92 %). Their rhodium complexes were evaluated in styrene hydroformylation, in which a moderate regioselectivity for the branched aldehyde was observed. The addition of a lithium salt led to a significant increase in the regioselectivity (25 %) for the branched aldehyde. This interesting observation has been rationalized based on a full two-level factorial design with 3 factors, including pressure, temperature and the Li/Rh ratio, using Rh/10 as model catalyst. The improvement of the regioselectivity in the presence of lithium salts has been interpreted through31PNMR spectroscopy and semiempirical PM6 computational studies.

Keywords: BINOL, diphosphite, ditopic, hydroformylation, rhodium, regioselectivity, Lithium ion.

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Article Details

VOLUME: 11
ISSUE: 2
Year: 2014
Page: [301 - 309]
Pages: 9
DOI: 10.2174/15701794113106660072
Price: $65

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