Scope of the organocatalysed asymmetric reductive amination of ketones with trichlorosilane

A highly active organocatalyst has been shown to affect the asymmetric reductive amination of ketones producing both aromatic and aliphatic amines. At 1 mol% catalyst loading, a series of structurally diverse chiral amines were quickly and economically prepared with good enantioselectivity and generally useful yield. The efficient synthesis of the calcimimetic (+)-NPS R-568 (67%, 89% ee) demonstrated the synthetic applicability of this methodology.     

Enantioselective organocatalytic reductive amination of aliphatic ketones by benzothiazoline as hydrogen donor

The chiral phosphoric acid-catalyzed enantioselective reductive amination of aliphatic ketones with aromatic amines was successfully achieved by the use of benzothiazoline as the hydrogen donor. Corresponding chiral aliphatic amines were obtained with excellent enantioselectivities.     

Highly enantioselective reductive amination of simple aryl ketones catalyzed by Ir-f-Binaphane in the presence of titanium(IV) isopropoxide and iodine

Using an Ir-f-Binaphane complex as the catalyst, complete conversions and high enantioselectivies (up to 96% ee) were achieved in the asymmetric reductive amination of aryl ketones in the presence of Ti(O(i)()Pr)(4) and I(2). A simple and efficient method of synthesizing chiral primary amines has been realized.     

低价钛引起的酰氯与脂肪酮的还原偶联反应

在低价钛(TiCl4-Zn)试剂作用下, 酰氯与两分子脂肪酮发生分子间交叉还原偶联反应生成烯烃3。     

Indirect and direct catalytic asymmetric reductive amination of 2-tetralone

Herein we report a one-pot catalytic asymmetric reductive amination of 2-tetralone. High-throughput screening of a small library of chiral ligands allowed us to perform the enantioselective hydrogenation of the intermediate enamine with up to 60% ee and a one-pot reaction with up to 47% enantiomeric excess of the desired amine.     

The rhodium catalyzed three-component reaction of diazoacetates, titanium(IV) alkoxides and aldehydes

The rhodium(II)-catalyzed three-component reaction of diazoacetates, titanium alkoxides and aldehydes is shown to give alpha-alkoxyl-beta-hydroxyl acid derivatives; the novel C-C bond formation reaction is proposed to occur through oxonium ylides derived from diazo compounds and titanium alkoxides, and followed by intermolecular trapping by aldehydes.     

Direct asymmetric aldol-Tishchenko reaction of aliphatic ketones catalyzed by syn-aminoalcohol-Yb(III) complexes

The asymmetric direct aldol condensation of aldehydes with ethyl- and propylketones is catalyzed by syn-alpha-aminoalcohol-Yb(OTf)3 complexes, yielding the anti-1,3-diol monoesters with high diastereocontrol and good enantioselectivity. Three adjacent stereogenic centers are created in a simultaneous aldol condensation and Evans-Tishchenko reduction in an acyclic system.     

Extraction of Nitric Acid and Np(IV) by some aliphatic ketones and alcohols

The extraction behaviour of HNO₃ and Np(IV) from aqueous nitrate solutions with some aliphatic alcohols and ketones using hexane, carbon tetrachloride, benzene and chloroform as diluents was studied. The acid concentration in the aqueous phase varied from 0.25 to 10 M and that of the extractant in the organic phase varied from 0.5 M to the undiluted fraction. In the alcohol systems, solutions of the same alcohol in the diluents CCl₄ and CHCl₃ showed similar capacity for acid extraction, and also in the same diluents, solutions of diisopropyl and diisobutyl alcohol showed similar capacity for extraction. Extraction of Np(IV) with the different ketones and alcohols used follow the same pattern as HNO₃.     

Palladium on activated carbon catalyzed reductive amination of aldehydes and ketones by triethylsilane

Various aldehydes and ketones were efficiently transformed into the corresponding amines using amine derivatives in the presence of triethylsilane and a catalytic amount of palladium on activated carbon in ethanol. The proposed method provides a one‐pot synthesis of various amines in excellent yields after short reaction times. Copyright © 2013 John Wiley & Sons, Ltd.     

Chiral diamides as efficient catalytic precursors for the borane-mediated asymmetric reduction of prochiral ketones

Chiral diamides [(2S)-5-oxo-2-(arylamino)carbonylpyrrolidines] derived from the abundantly available (S)-glutamic/(S)-pyroglutamic acids were successfully utilized as effective chiral catalytic precursors in the borane-mediated asymmetric reduction of prochiral ketones in refluxing toluene, to provide the corresponding secondary alcohols with up to 91% enantiomeric purities.     

Novel anti-Prelog stereospecific carbonyl reductases from Candida parapsilosis for asymmetric reduction of prochiral ketones

The application of biocatalysis to the synthesis of chiral molecules is one of the greenest technologies for the replacement of chemical routes due to its environmentally benign reaction conditions and unparalleled chemo-, regio- and stereoselectivities. We have been interested in searching for carbonyl reductase enzymes and assessing their substrate specificity and stereoselectivity. We now report a gene cluster identified in Candida parapsilosis that consists of four open reading frames including three putative stereospecific carbonyl reductases (scr1, scr2, and scr3) and an alcohol dehydrogenase (cpadh). These newly identified three stereospecific carbonyl reductases (SCRs) showed high catalytic activities for producing (S)-1-phenyl-1,2-ethanediol from 2-hydroxyacetophenone with NADPH as the coenzyme. Together with CPADH, all four enzymes from this cluster are carbonyl reductases with novel anti-Prelog stereoselectivity. SCR1 and SCR3 exhibited distinct specificities to acetophenone derivatives and chloro-substituted 2-hydroxyacetophenones, and especially very high activities towards ethyl 4-chloro-3-oxobutyrate, a β-ketoester with important pharmaceutical potential. Our study also showed that genomic mining is a powerful tool for the discovery of new enzymes.     

Low-valent titanium induced reductive cyclization of nitro compounds and aliphatic ketones:facile synthesis of 3,4-dihydro-(2H) -1,2,4-benzothiadiazine-1,1-dioxides

The intermolecular reductive cyclization of o-nitrobenzene-sulfonamides with aliphatic ketones induced by TiCl4/Sm system was studied and a series of 3,3-disubstituted-3,4-dihydro-(2H)-1,2,4-benzothiadiazine-1,1-dioxides were synthesized in moderate to high yields under mild and neutral conditions.     

The reductive amination of aldehydes and ketones by catalytic use of dibutylchlorotin hydride complex

The reductive amination of aldehydes or ketones using Ph(2)SiH(2) or PhSiH(3) has been effectively promoted by the direct use of Bu(2)SnClH-pyridine N-oxide as a catalyst; this method has advantages in terms of its mild conditions and wide application to various carbonyls and amines, including aliphatic examples.     

Direct reductive amination of aldehydes and ketones using phenylsilane: catalysis by dibutyltin dichloride

A procedure for direct reductive amination of aldehydes and ketones was developed which uses phenylsilane as a stoichiometric reductant and dibutyltin dichloride as a catalyst. Suitable amines included anilines and dialkylamines but not monoalkylamines.     

Intermolecular asymmetric reductive aldol reaction of ketones as acceptors promoted by chiral Rh(Phebox) catalyst

[reaction: see text] The conjugate reduction of cinnamates with hydrosilane and chiral Rh(Phebox-ip) catalyst in the presence of excess acetone is shown to provide the corresponding intermolecular reductive aldol product in extremely high enantioselectivity (up to 98%). Several cinnamates and crotonate substrates and several ketone acceptors were also examined.     

Highly regioselective, catalytic asymmetric reductive coupling of 1,3-enynes and ketones

[reaction: see text] Highly regioselective, catalytic asymmetric reductive coupling reactions of 1,3-enynes and ketones have been achieved using catalytic amounts of Ni(cod)(2) and a P-chiral, monodentate ferrocenyl phosphine ligand. These couplings represent the first examples of catalytic, intermolecular reductive coupling of alkynes and ketones, enantioselective or otherwise, and afford synthetically useful 1,3-dienes possessing a quaternary carbinol stereogenic center in up to 70% ee.     

手性方酸衍生物的合成及在前手性酮的不对称催化还原反应中的应用研究进展

本文评述手性方酸衍生物的研究进展，包括多个系列的新型手性方酰化氨基醇及氨基酸配体的设计合成以及它们在前手性单酮和二酮的不对称催化还原反应中的应用。