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Lanthanide (III) salt complexes: Arrayed acid‐base networks for enantioselective catalysis. The nitroaldol reaction upon aldehydes and trifluoromethylketones
Author(s) -
Saá José M.,
Tur Fernando,
González José
Publication year - 2009
Publication title -
chirality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.43
H-Index - 77
eISSN - 1520-636X
pISSN - 0899-0042
DOI - 10.1002/chir.20698
Subject(s) - chemistry , enantioselective synthesis , trifluoromethanesulfonate , lanthanide , catalysis , isostructural , chirality (physics) , trifluoromethyl , salt (chemistry) , medicinal chemistry , hydrolysis , stereochemistry , organic chemistry , crystal structure , alkyl , ion , nambu–jona lasinio model , chiral symmetry breaking , physics , quantum mechanics , quark
Abstract Shelf stable, chiral‐at‐metal, D 3 symmetric, 3:1 complexes of lanthanide (III) triflate salts are easily available by complexation with binolam (3,3′‐diethylaminomethyl‐2,2′‐dihydroxy‐1,1′‐dinaphthalene) 1 or binolamo (3,3′‐diethylaminooxymethyl‐2,2′‐dihydroxy‐1,1′‐dinaphthalene) 2 ligands. The resulting compounds 3Ln and 4Ln are isostructural, as demonstrated by their spectroscopic data, and possess an arrayed acid‐base LABABB network. Complexes are kinetically labile, and in solution undergo hydrolysis by water. The lanthanum complex derived from binolam, i.e., (Δ, S,S,S )‐ (binolam) 3 .la(OTf) 3 3La was found to be the most active catalyst in promoting direct nitroaldol reactions upon aldehydes and trifluoromethyl ketones, thereby giving rise to secondary nitroalcohols and tertiary α‐trifluoromethyl‐β‐nitroalcohols, respectively, with high ee in both cases. Enantiomerically enriched tertiary nitroalcohols were easily reduced to the corresponding aminoalcohols having a quaternary asymmetric carbon without loss of enantiomeric purity. Chirality 2009. © 2009 Wiley‐Liss, Inc.