Copper‐Chiral Camphor β‐Amino Alcohol Complex Catalyzed Asymmetric Henry Reaction

Abstract

Four novel chiral amino alcohols were synthesized from D-(+)-camphor and utilized as ligands in a Cu(I)-catalyzed asymmetric Henry reaction. The reactions were carried out under mild conditions with excellent enantioselectivities and moderate yields without the exclusion of air or moisture. The highest enantioselectivity was observed up to 94% enantiomeric excess (ee) with ligand in toluene at room temperature.

(3S,4S)‐N‐substituted‐3,4‐dihydroxypyrrolidines as ligands for the enantioselective Henry reaction

“…This same trend, in which aromatic solvents lead to better induction of chirality, has been previously observed. [ 6,47–49 ]…”

“…[ 4,5 ] A variety of chiral ligands with different types of functionalities (amino alcohols, diols, diamines, salen, salan, amino phosphines, among others) have been reported in the literature. [ 1,6–12 ] The use of metals such as La, Mo, Zn, Co, Cr, Rh and with special emphasis Cu [ 13 ] has also been described. [ 5,14–18 ] Ligands containing a pyrrolidine moiety have been used in various catalytic reactions, with good results.…”

Biphenyl-Based Bis(thiourea) Organocatalyst for Asymmetric and syn-Selective Henry Reaction

“…Absolute and relative configuration of the target adducts 11a-11s and 11u was determined by comparison of 1 H NMR spectra and the relative elution order of resolved peaks with authentic samples and literature data. 12,[17][18][19][20][21][22][23] Absolute and relative configuration of 11t was assigned (S,S)-by analogy with other β-nitro alcohols. A standard septum capped 2-mL HPLC vial equipped with a small magnetic stirring bar was charged with (R a )-CAT or (S a )-CAT (7.5 mg; 10 µmol), an appropriate aldehyde (100 µmol) and dry THF (200 µL).…”

“…Chiral HPLC chromatogram of (R)-11k (ee = 86%).! S#44!2-nitro-1-(4-(trifluoromethyl)phenyl)ethan-1-ol (11l)20 HPLC conditions: i PrOH-Hp, 20:80, 0.5 mL/min, 5 °C (λ = 230 nm). rac-11l was prepared according to GP 1 (isolated yield 82%).…”

Transfer Hydrogenation of Ketones Using Pyridine-Aminoalcohol Ligands

“…Although direct hydrogenation is more widely applied, TH is a preferable method because of the ready availability of hydrogen donor and low cost of reducing agents [1][2][3][4][5][6]. Over the last two decades, various aminoalcohol ligands (I-III) have been tested in many reactions, such as the addition of diethyl zinc to aldehydes [7,8] Friedel-Crafts alkylation of indoles [9], Henry reaction [10] and transfer hydrogenation of ketones [11][12][13][14][15]. Brunner and co-workers also prepared pyridine-aminoalcohol ligands (IV-V), which contain phenolic hydroxyl group and investigated their catalytic activities in TH ( Figure 1) [16][17][18].…”