Chiral bis(amino alcohol)oxalamides as ligands for asymmetric catalysis. Ti(IV) catalyzed enantioselective addition of diethylzinc to aldehydes

Blay, Gonzalo; Fernández, Isabel; Marco‐Aleixandre, Alicia; Pedro, José R.

doi:10.1016/j.tetasy.2005.01.039

Cited by 43 publications

(17 citation statements)

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“…The design and synthesis of new molecules able to act as chiral symmetric ligands in catalytic asymmetric reactions is one of the most important goals in modern organic chemistry. 42 The conformationally constrained metal chelate and the presence of stereocenters close to the nitrogen donor atoms assure a well-ordered chiral environment at the catalytic site. 43 Here, we report the synthesis of two chiral bis(amino alcohol)oxalamides from aminoalcohols derived from natural aminoacids, and their application to the preconcentration of Cu, Cd, Co and Ni by using cloud-point extraction methodology prior to atomic-absorption determination.…”

Section: Introductionmentioning

confidence: 99%

Synthesis of Bis(amino alcohol)oxalamides and Their Usage for the Preconcentration of Trace Metals by Cloud Point Extraction

et al. 2008

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C2-Symmetric two bis(amino alcohol)oxalamides (diamidediols) were synthesized and fully characterized. A new method was developed and successfully applied for the simultaneous preconcentration of both trace and toxic metals in water, by using C2-symmetric compounds. Under the optimum experimental conditions (i.e. pH = 10.10% w/v octylphenoxy-polyethoxyethanol (Triton X-114)), calibration graphs were linear in the range of 2.5 -25.0 ng mL -1 for Cu and Cd, 5.0 -25.0 ng mL -1 for Co and Ni. The enrichment factors were 18, 23, 18 and 20 for Cd, Cu, Co and Ni in the case of DAD1, respectively; 20, 22, 17 and 20 for Cd, Cu, Co and Ni in the case of DAD2. The limits of detection for DAD1 were found to be 0.45, 0.50, 1.25 and 0.60 ng mL -1 for Cd, Cu, Co and Ni, respectively, and for DAD2 were found to be 0.44, 0.25, 0.60 and 1.55 ng mL -1 for Cd, Cu, Co and Ni, respectively. The developed method was applied to the determination of Cu, Cd, Co and Ni in water samples and certified reference materials with satisfactory results.

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Section: Introductionmentioning

confidence: 99%

Synthesis of Bis(amino alcohol)oxalamides and Their Usage for the Preconcentration of Trace Metals by Cloud Point Extraction

et al. 2008

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“…13 Enantioselectivity (45% ee) was achieved after a 6 h reaction with 10.0 mol% of 1 (entry 8 in Table 1). A larger amount of 1 (20%) did not increase enantioselectivity significantly (entry 9 in Table 1) probably because the sugar derivative 1 acts with Ti(IV) forming a chiral catalyst of the Ti(IV)-sugar type with an optimum amount of 1, Lowering the temperature from room temperature to 0 °C and -20 °C decreased conversion of benzaldehyde into 1-phenyl-1-propanol (Table 2), but the lower temperature did not significantly increase the enantioselectivity (ee%) of the reaction (Table 2).…”

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confidence: 99%

Enantioselective addition of diethylzinc to benzaldehyde catalyzed by an organometallic Ti(IV) compound and a xylose derivative

Parada¹,

Herrera²,

Pedraza³

2009

J. Braz. Chem. Soc.

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Um derivado da D-xylose, 1,2-O-isopropilideno-α-D-xilofuranose (1), com Ti(O i Pr) 4 foi usado como catalisador chiral na alquilação assimétrica do benzaldeído com dietilzinco (Et 2 Zn) para produção de 1-fenil-1-propanol em alto rendimento (conversão de 90%) e enantiosseletividade moderada (45% ee (S)). As condições ótimas (conversão e enantiosseletividade) para o sistema catalítico formado por 1 e Ti(IV) foram 10.0 mol % de 1 e 1 equivalente de Ti(IV) com relação ao benzaldeído em CH 2 Cl 2 como solvente, a temperatura ambiente. Na alquilação assimétrica do benzaldeído com Et 2 Zn, o composto 1 em quantidade sub-estequiométrica com Ti(O i Pr) 4 forma um catalisador quiral do tipo Ti(IV)-açúcar, o que assegura uma conversão com bom rendimento e a enantiosseletividade da reação.A derivative of D-xylose, 1,2-O-isopropylidene-α-D-xylofuranose (1), with Ti(O i Pr) 4 was used as a chiral catalyst in the asymmetric alkylation of benzaldehyde with diethylzinc (Et 2 Zn) for the high-yield production (90% conversion) and moderate enantioselectivity (45% ee (S)) of 1-phenyl-1-propanol. Optimum conditions (conversion and enantioselectivity) for the catalytic system formed by 1 and Ti(IV) were 10.0 mol % of 1 and 1 equivalent of Ti(IV) with respect to benzaldehyde in CH 2 Cl 2 as a solvent, at room temperature. In the asymmetric alkylation of benzaldehyde with Et 2 Zn compound 1 in substoichiometric amount with Ti(O i Pr) 4 forms a chiral catalyst of the Ti(IV)-sugar type that ensures the good-yield conversion and the enantioselectivity of the reaction.

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“…However, with this system the alkynylation product 6aa was obtained in racemic form with low yield, together with the 4‐ethyl derivative. Then, we screened the use of bis(hydroxyamide) ligands L1 and L2 that we had successfully used in the past for the enantioselective diethylzinc addition to aldehydes (Table 1, entries 1 and 2) 26. Although L1 led to the expected product in racemic form, the encouraging result obtained with ligand L2 prompted us to synthesize and test other C 2 ‐symmetrical bis‐hydroxyamides L3 – L12 .…”

Section: Methodsmentioning

confidence: 99%

Enantioselective Synthesis of 4‐Substituted Dihydrocoumarins through a Zinc Bis(hydroxyamide)‐Catalyzed Conjugate Addition of Terminal Alkynes

et al. 2013

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Chiral bis(amino alcohol)oxalamides as ligands for asymmetric catalysis. Ti(IV) catalyzed enantioselective addition of diethylzinc to aldehydes

Cited by 43 publications

References 50 publications

Synthesis of Bis(amino alcohol)oxalamides and Their Usage for the Preconcentration of Trace Metals by Cloud Point Extraction

Synthesis of Bis(amino alcohol)oxalamides and Their Usage for the Preconcentration of Trace Metals by Cloud Point Extraction

Enantioselective addition of diethylzinc to benzaldehyde catalyzed by an organometallic Ti(IV) compound and a xylose derivative

Enantioselective Synthesis of 4‐Substituted Dihydrocoumarins through a Zinc Bis(hydroxyamide)‐Catalyzed Conjugate Addition of Terminal Alkynes

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