The asymmetric transfer hydrogenation (ATH) reaction of prochiral ketones is an important method to produce chiral alcohols. Recently, the application of chiral amino acids and their derivatives as ligands in ATH of prochiral ketones promoted by the ruthenium, rhodium or iridium complexes have been attracted more attentions. Herein the catalytic properties of amino acids, amino acid based amides, thioamides, hydroxamic acids, hydrazides, amino alcohols and hydroxy amides as ligands in the ruthenium, rhodium or iridium catalyzed ATH of prochiral ketones have been overviewed. Keywords chiral amino acid; derivative of amino acid; metal complex of amino acid; asymmetric transfer hydrogenation
Chiral amine is a kind of important chemicals. Several L-amino acid based chiral diamines and triamines were prepared by ring-opening of substituted aziridines with L-amino acid esters in the matrix of silica without solvent. The ring-opening reactions were promoted by silica and accelerated by ultrasound radiation. The L-amino acid esters reacted with substituted aziridine 2 to give diamine 3 at first, then diamine 3 reacted with aziridine 2 again to form triamine 4. Compared with L-amino acid esters 1, compound 3 had a higher activity. (S)-Methyl pyrrolidine-2-carboxylate (1d) reacted with (R)-2-isopropyl-1-tosylaziridine (5) selectively yielding (S)-methyl 1-[(R)-3-methyl-2-(4-methylphenyl sulfonamide)butyl]pyrrolidine-2-carboxylate (6b) through the ring opening at 1,3-position of aziridine. All obtained compounds were characterized by 1 H NMR, 13 C NMR, IR and elemental analysis. 4c was analyzed by X-ray diffraction as well. Keywords amino acids; substituted aziridine; ring opening; solid phase synthesis; X-ray diffraction 1 结果与讨论 1.1 手性氨基酸衍生物的合成 我们首先尝试以 LiClO 4 为催化剂, L-苯丙氨基酸甲 酯(1a)在回流的乙腈中与 N-对甲基苯磺酰氮丙啶(2)的 开环反应, 经 TLC 监测, 20 h 后仍没有发生反应(Eq.
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