title: Novel carbohydrate-based bifunctional organocatalysts for nucleophilic addition to nitroolefins and imines.
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.
authors: Dipartimento di Chimica Organica e Industriale, CISI, Universitá degli Studi di Milano, via Golgi 19, I-20133, Milano, Italy.
authors: Alessandra
authors: A
authors: Puglisi
authors: Maurizio
authors: M
authors: Benaglia
authors: Laura
authors: L
authors: Raimondi
authors: Luigi
authors: L
authors: Lay
authors: Laura
authors: L
authors: Poletti
mesh_terms: D000475:Alkenes / Q000737:chemistry*; D002241:Carbohydrates / Q000737:chemistry*; D002384:Catalysis; D007097:Imines / Q000737:chemistry*; D008958:Models, Molecular; D015394:Molecular Structure; D017672:Nitrogen Compounds / Q000737:chemistry*
chemical_list: D000475:Alkenes; D002241:Carbohydrates; D007097:Imines; D017672:Nitrogen Compounds