Enantioselective cyanoformylation of aldehydes organocatalyzed by recyclable cinchonidine ammonium salts

Autor:	Francisco Ortega, Silvia Tari, Rafael Chinchilla, Carmen Nájera
Rok vydání:	2009
Předmět:	chemistry.chemical_classification Organic Chemistry Enantioselective synthesis Salt (chemistry) Catalysis Inorganic Chemistry chemistry.chemical_compound chemistry Organic chemistry Ammonium Methyl cyanoformate Physical and Theoretical Chemistry Cinchonidine Triethylamine
Zdroj:	Tetrahedron: Asymmetry. 20:2279-2286
ISSN:	0957-4166
DOI:	10.1016/j.tetasy.2009.08.007
Popis:	Enantiomerically enriched O -methoxycarbonyl cyanohydrins were obtained using an enantioselective addition of methyl cyanoformate to aldehydes organocatalyzed by a dimeric anthracenyldimethyl-derived cinchonidine ammonium salt (1 mol % catalyst loading) in the presence of substoichiometric amounts of triethylamine (20 mol %). Aromatic and heteroaromatic aldehydes usually afford high enantioselectivities (up to 96%) and quantitative yields of the corresponding O -methoxycarbonyl cyanohydrins, whereas aliphatic and α,β-unsaturated aldehydes give lower enantioselectivities (up to 60%) in high yields. The observed sense of the enantioselection was always the same, and the organocatalyst was almost quantitatively recovered by ether-promoted precipitation without any loss of activity. The use of resin-supported cinchonidine-derived ammonium salts as an organocatalyst in this transformation was also explored.
Databáze:	OpenAIRE
Externí odkaz:	https://explore.openaire.eu/search/publication?articleId=doi_________::1817afa21fc22f87804e9c7719cb6df0 https://doi.org/10.1016/j.tetasy.2009.08.007 Zobrazit plný text záznamu Full Text from ScienceDirect