Synthesis and application of C2-symmetrical bis-β-amino alcohols based on the octahydro-cyclopenta[b]pyrrole system in the catalytic enantioselective addition of diethylzinc to benzaldehyde

Asymmetric catalytic ethylation of benzaldehyde utilizing a series of new, tetradental bis-β-amino alcohols based on the octahydro-cyclopenta[b]pyrrole system—derived from an industrial waste material—is presented. Attention is focused on steric aspects of the catalyst(-precursor) structure. Furthermore, the catalytic efficiency of the ethylene-bridged, C₂-symmetrical bis-β-amino alcohols is compared to related ‘monomeric’ structures. Potent chiral ligands, which are highly effective even at concentrations of below 2 mol%, have been developed reaching excellent enantioselectivities up to 100% ee.     

Synthesis of novel β-amino alcohols and their application in the catalytic asymmetric sulfoxidation of sulfides

Novel chiral norephedrine-based β-amino alcohol ligands containing a thiophene ring were prepared from norephedrine and substituted furan carbaldehydes (methyl- or ethyl-substituted) and used in combination with VO(acac)₂ for the asymmetric oxidation of aryl methyl sulfides using H₂O₂ as an oxidant. Amino alcohol derived Schiff bases 4,5a–b gave higher enantiomeric excesses than amino alcohol-derived reduced Schiff based ligands 6,7a–b. Of these chiral ligands, (1S,2R)-5b and (1S,2R)-7b gave high yields (90%) with moderate to high enantioselectivities (78%, 96% ee, respectively). The oxidation of other aryl methyl sulfides with (1S,2R)-5b and (1S,2R)-7b as ligands afforded the corresponding sulfoxides in 60–89% yields and with 92–99% ee.     

Synthesis of rare earth catalysts and their applications for enantioselective synthesis of heterocyclic β-amino alcohols

A new family of chiral lanthanide complexes derived from (R)-binaphthol has been synthesized by a one-pot procedure using only commercially available substrates. These complexes were evaluated for the aminolysis of meso-epoxides and proved to be efficient enantioselective catalysts. The samarium complex coordinated by two (R)-binaphthoxide ligands was the most enantioselective catalyst of this series. β-Amino alcohols including heterocycles have been isolated with enantiomeric excesses up to 84%.     

Synthesis of 2-functionally substituted oxazolines and oxazolidines from methyl bromopropiolate and Β-amino alcohols

The reaction of methyl bromopropiolate with -amino alcohols containing a primary amino group generally results in the formation of 2-(methoxycarbonylmethyl)-²-1,3-oxazolines, while in the reaction with N-methyl- and N,N-dimethyl-substituted -aminoalcohols, 2-(methoxycarbonylmethylene)-1,3-oxazolidines, or their salts are formed.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 406–409, March, 1991.     

Synthesis and application of C2-symmetric diamino FERRIPHOS as ligands for enantioselective Rh-catalyzed preparation of chiral α-amino acids

C₂-Symmetrical ferrocenyl diamino diphosphines (diamino FERRIPHOS ligands) proved to be excellent ligands for the rhodium-catalyzed enantioselective reduction of methyl α-acetamidoacrylates. The straightforward synthesis, their air stability and the easy modification of their structure makes these ligands especially interesting for transition metal-catalyzed hydrogenations. α-Amino acids with enantioselectivities greater than 95% (and up to 99.3% ee) were obtained with no need of further recrystallization.     

Solubilities and solvation of bis-(2,2′-bipyridyl)- and bis-(1,10-phenanthroline)dicyanoiron(II) in alcohols

Summary Solubilities of bis-(2,2-bipyridyl)- and bis-(1,10-phenanthroline)dicyanoiron(II) are reported for a range of primary aliphatic alcohols, from MeOH to 1-decanol. The established trends are compared with those for other solutes, and for the title compounds in H₂O-alcohol solvent mixtures.     

Synthesis of new chiral 1,2,3,4-tetrahydroisoquinoline β-amino alcohols from L-DOPA

Four new chiral 1,2,3,4-tetrahydroisoquinoline-derived β-amino alcohols were synthesized from L-DOPA in good yields.The structures of the target compounds were confirmed by 1H NMR,13C NMR and MS.     

Synthesis of γ-keto alcohols and dihydrofurans from 2-furanpropanols

Summary A method was developed for the preparation of-keto alcohols and hence 2,3-dihydrofurans by the catalytic hydrogenation of 2-furanpropanols over platinized charcoal at 220° with formation of acetic esters of-keto alcohols, from which as a result of methanolysis-keto alcohols and dialkyldihydrofurans are formed.     

Diastereo- and enantioselective preparation of β-alkylhomoallylic alcohols : Synthesis of serricornin and corynomycolic acid

A new and efficient method for the preparation of four possible stereoisomers of β-alkylhomoallylic alcohols 1 has been developed which is based on the diastereoselective addition of nucleophiles to optically active α-alkyl-β-trimethylsilyl-β,γ-unsaturated carbonyl compounds. The utility of this reaction is demonstrated by the synthesis of naturally occurring serricornin and corynomycolic acid.     

Synthesis of γ-amino alcohols from aldehydes, enamines, and trichlorosilane using Lewis base catalysts

The reaction of aldehydes, enamines, and trichlorosilane in the presence of a Lewis base catalyst, particularly N-methylpyrrolidinone and DMF, affords γ-amino alcohols with a high diastereoselectivity. The method consists of C-C bond formation between an aldehyde and an enamine, and a subsequent intramolecular reduction of the resulting iminium ion intermediate. In most cases, one diastereomer is exclusively generated, and we propose a transition state model for the intramolecular reduction of the iminium ion intermediate. Enamines, prepared beforehand from the corresponding ketone and amine, can be used in the reaction without purification. Furthermore, enantioselective catalysis using a chiral Lewis base catalyst is possible, although the enantioselectivity is modest. The current tandem method offers the first, concise synthetic method of γ-amino alcohols from aldehydes and enamines.     

Synthesis of macrocycles and their application as chiral solvating agents in the enantiomeric recognition of carboxylic acids and α-amino acid derivatives

The chiral macrocycles 1 and 2 with multiple binding sites have been synthesized from D-phenylalanine as chiral solvating agents (CSAs) for the enantiomeric discrimination and determination of the enantiomeric excess of carboxylic acids and a-amino acids derivatives by the ¹H NMR spectroscopy. The results show that chiral macrocycles 1 and 2 are effective CSAs towards the carboxylic acids and a-amino acids derivatives.     

Synthesis of fluorescent Ag nanoclusters and their application in α-l-fucosidase detection

Highly fluorescent Ag nanoclusters (NCs) were successfully prepared by a simple and nontoxic approach, and the as-prepared Ag NCs could be utilized for the AFu detection with a lower detection limit of 0.001 U L(-1).     

Synthesis of α-amino oximes and bis-α-amino oximes from the monoterpene hydrocarbons 3-carene and α-pinene and α,ω-diamines

The reaction of nitroso chlorides of natural monoterpene hydrocarbons, 3-carene and -pinene, with simple ,-diamines (1,2-diaminoethane, 1,3-diaminopropane, piperazine, 1,6-diaminohexane, diethylenetriamine) results in the formation of -amino oximes and bis--amino oximes. The product structures were proved by spectroscopy. The procedures of separation and purification of diamino oximes and diamino dioximes are described. Detailed analysis of the ¹H and ¹³C NMR spectra of the new chiral nitrogen-containing derivatives was carried out.     

Synthesis and application in enantioselective hydrogenation of new free and chromium complexed aminophosphine–phosphinite ligands

A straightforward synthesis of new free and Cr(CO)₃ complexed AMPP ligands (4–7) is described starting from (S)-indoline-2-carboxylic acid. The ligands were applied successfully in the asymmetric hydrogenation of α-functionalized ketones i.e. a ketolactone 8, a ketoamide 9 and an aminoketone 10 leading to the corresponding optically active alcohols in 99, 97, and 99% ee respectively.     

Synthesis of novel optically pure quinolyl-β-amino alcohol derivatives from 2-amino thiophenol and chiral α-acetylenic ketones and their IBX-mediated oxidative cleavage to N-Boc quinolyl carboxamides

A methodology directed toward the stereoselective synthesis of novel quinolyl glycines is presented. This strategy is based on the cyclocondensation reaction between 2-amino thiophenol 4 and chiral acetylenic ketones of the type 3 containing a latent α-amino acid functionality. The initially formed benzo[b][1,4]thiazepine derivatives 5, readily undergo sulphur extrusion in refluxing toluene to yield the corresponding 2,4-disubstituted quinolines 6. Subsequent oxazolidine ring opening followed by in situ re-protection of the amino group afforded the corresponding quinolyl-β-amino alcohols 8a–8f in enantiomerically pure form and good overall yields. The derivatives 8 are in principle suitable precursors for the synthesis of novel optically pure quinolyl glycines through oxidation of the alcohol side chain. However, these amino alcohol derivatives 8, did not afford the expected quinolyl glycines 10 using numerous oxidising agents and reaction conditions. Instead, by reacting 8 with the mild oxidising reagent IBX 11, an oxidative CC cleavage leading to the N-Boc quinolyl carboxamides 12 took place.     

Synthesis of new C2-symmetric bis(β-hydroxy amide) ligands and their applications in the enantioselective addition of alkynylzinc to aldehydes

A series of chiral C₂-symmetric bis(β-hydroxy amide) ligands was synthesized via the reaction of isophthaloyl dichloride and amino alcohols derived from l-amino acid. The titanium(IV) complex of C₂-symmetric chiral ligand 3b was effective for the asymmetric alkynylation of aldehydes and the propargyl alcohols were obtained in high yields (up to 94%) and high enantiomeric excesses (up to 98%) under optimized conditions. The results obtained using ligand 3h support that the two β-hydroxy amide moieties in these ligands behave as two independent ligands in the catalytic system.     

The versatile roles of ammonium salt catalysts in enantioselective reduction and alkylation of α,β-unsaturated aldehydes: iminium catalysis, enamine catalysis and acid catalysis

A novel strategy for highly efficient utilization of chiral ammonium salt catalysts has been described in this paper. Three kinds of catalytic functions including iminium catalysis, enamine catalysis, and acid catalysis of chiral ammonium salt catalysts, have been achieved in the enantioselective reduction and alkylation reaction of α,β-unsaturated aldehydes with alcohols.     

Ligand-controlled synthesis of vanadium(I) β-diketiminates and their catalysis in cyclotrimerization of alkynes

Three dimeric vanadium(I) β-diketiminates [V{μ-(η(6)-ArN)C(Me)CHC(Me)C(N-Ar)}](2) (Ar = 2,6-Me(2)C(6)H(3) (2), 2,6-Et(2)C(6)H(3) (3), 9-anthracenyl (4)) were prepared and isolated upon reduction of their corresponding dichloro precursors VCl(2)(Nacnac). Compounds 2-4 all show a structure with each vanadium atom being η(2) bonded to the β-diketiminate framework and η(6) bonded to a flanking ring of a β-diketiminato ligand, attached to the other vanadium centre within the dimer. No metal-metal bonding interactions are observed in these dimers due to long vanadium-vanadium separations. Compounds 2-4 display an antiferromagnetic exchange between the two vanadium centres. An imido azabutadienyl complex (η(2)-PhCC(H)C(Ph)NC(6)H(3)-2,6-(i)Pr(2))VN(C(6)H(3)-2,6-(i)Pr(2))(OEt(2)) (5) was isolated from the reduction of VCl(2)(HC(C(Ph)NC(6)H(3)-2,6-(i)Pr(2))(2)) by KC(8). Compounds 2-4 and the inverted-sandwich divanadium complex (μ-η(6):η(6)-C(6)H(5)Me)[V(HC(C(Me)NC(6)H(3)-2,6-(i)Pr(2))(2))](2) (1) reduce Ph(2)S(2) to give two vanadium dithiolates V(SPh)(2)[(HC(C(Me)NC(6)H(3)-2,6-R(2))(2))] (R = Et (6), (i)Pr (7)) through an oxidative addition. Most notably, 1 and 3 catalyze the cyclotrimerization of alkynes, giving tri-substituted benzenes in good yields and a 1,3,5-triphenylbenzene coordinated intermediate 8 was isolated and characterized.