Glucosamine has been selected as a cheap and readily available chiral scaffold for the synthesis of a series of novel enantiomerically pure bifunctional organocatalysts bearing a tertiary amino group in proximity to a (thio)urea group. The catalytic behaviour of these compounds, both as neutral and N-protonated species, was investigated using the addition of acetylacetone to β-nitrostyrene as a model reaction. Under optimized experimental conditions, chemical yields up to 93% and enantioselectivities up to 89% were obtained. Semiempirical (AM1) computational studies allowed to find a theoretical rationale for the chemical and stereochemical behaviour of the catalyst of choice. These catalysts were also preliminarily investigated as promoters in the addition of diethyl malonate to the N-Boc imine of benzaldehyde, affording the product in up to 81% ee.

Novel carbohydrate-based bifunctional organocatalysts for nucleophilic addition to nitroolefins and imines / A. Puglisi, M. Benaglia, L.M. Raimondi, L. Lay, L. Poletti. - In: ORGANIC & BIOMOLECULAR CHEMISTRY. - ISSN 1477-0520. - 9:9(2011), pp. 3295-3302.

Novel carbohydrate-based bifunctional organocatalysts for nucleophilic addition to nitroolefins and imines

A. Puglisi
Primo
;
M. Benaglia
;
L.M. Raimondi;L. Lay
Penultimo
;
L. Poletti
Ultimo
2011

Abstract

Glucosamine has been selected as a cheap and readily available chiral scaffold for the synthesis of a series of novel enantiomerically pure bifunctional organocatalysts bearing a tertiary amino group in proximity to a (thio)urea group. The catalytic behaviour of these compounds, both as neutral and N-protonated species, was investigated using the addition of acetylacetone to β-nitrostyrene as a model reaction. Under optimized experimental conditions, chemical yields up to 93% and enantioselectivities up to 89% were obtained. Semiempirical (AM1) computational studies allowed to find a theoretical rationale for the chemical and stereochemical behaviour of the catalyst of choice. These catalysts were also preliminarily investigated as promoters in the addition of diethyl malonate to the N-Boc imine of benzaldehyde, affording the product in up to 81% ee.
enantioselective Michael addition; tertiary amine; thiourea organocatalysts; cooperative catalysis; asymmetric catalysis; acetylacetone; saccharides; derivates; strecker; system
Settore CHIM/06 - Chimica Organica
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2434/162324
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