Stereochemical requirements for fragmentation of homoallylic epoxy alcohols

The fragmentation of 5,6-epoxynorbornan-2-ol and 5,6-epoxynorbornan-2-one have been studied under both acidic and basic conditions. These processes show a clear preference for syn periplanar alignment of breaking bonds.     

Ion-pair supercritical fluid chromatography of metoprolol and related amino alcohols on diol silica

In this paper, a chromatographic system based on carbon dioxide with methanol as mobile phase, and diol silica as stationary phase has been investigated for metoprolol and related amino alcohols by addition of strong acids to systems with triethylamine base as primary additive. Standard conditions used were 10% of methanol, containing 24 mM of acid and 18 mM of triethylamine, in carbon dioxide with a flow rate of 1.5 ml min(-1). The column dimensions were 125 mm x 4 mm I.D. and kept at 40 degrees C with a back pressure of 150 bar. Effects on selectivity were stronger with trifluoroacetic acid than with ethanesulfonic acid. From a large set of related analytes, it was shown that selectivity changes were significant when the structure close to the nitrogen of the amino alcohol analyte differed. The stability of the column in the short time perspective was examined and it showed negligible changes. For a diastereoisomeric pair, not resolved in a basic system with triethylamine nor by addition of ethanesulfonic acid, resolution improved to about 2.1 with trifluoroacetic acid. The described approach offers a way to tune the selectivity of SFC systems when amines are analyzed without the need to change stationary phase for the chromatographic separation.     

Reaction of tertiary diacetylenic alcohols with amino alcohols

Conclusions It was shown that nitrogen-containing ethynyl vinyl ethers can be synthesized from tertiary diacetylenic alcohols and amino alcohols in the presence of alkaline catalysts.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2604–2605, November, 1970.     

Synthesis of enantiopure cyclobutane amino acids and amino alcohols

(−)-(1R,3S)-3-Amino-2,2-dimethylcyclobutanecarboxylic acid and (+)-(1R,3S)-3-amino-2,2-dimethylcyclobutylmethanol, which can be used to prepare enantiopure oligopeptides and cyclobutane-based carbocyclic nucleosides, were synthesized from (+)-(1R)-α-pinene.     

Detection of amino alcohols and diamines

Summary Test-tube and spot reaction procedure are presented for the detection of-amino alcohols and aliphatic 1,2-diamino compounds. The test is dependent on the reduction of periodate in sulfuric acid medium, followed by the precipitation of silver iodate in nitric acid solution.

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Zusammenfassung Aliphatische 1,2-Diaminoverbindungen und-Aminoalkohole reduzieren Perjodat in schwefelsaurer Lösung und geben dann einen Niederschlag von Silberjodat in salpetersaurer Lösung. Die Probe wurde im Reagensglas und auf dem Uhrglas erfolgreich durchgeführt.

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Résumé On présente des procédés en tubes à essai et par réaction à la touche pour déceler les-amino alcools et les composés diamino-1,2 aliphatiques. L'essai consiste en la réduction des periodates en milieu acide sulfurique, suivie de la précipitation de l'iodate d'argent en solution acide nitrique.

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Dedicated to Prof. Dr. Ing.Fritz Feigl on occasion of his 70th birthday.     

Racemization of chiral amino alcohols: Catalyst selection and characterization

Summary The transformation of R-(-)-2-amino-1-butanol to the racemic mixtures was selected as a model for the racemization of chiral amino alcohols. A 40% Co/γ-Al2O3 catalyst was found to be active enough for the complete racemization in over 80% yield and characterized by XRD, XPS, TPR and BET, etc.     

Reactions of alkoxy and amino derivatives of silacyclobutane with amino alcohols

2-(N,N-Dimethylamino)ethanol readily replaces the MeO and Et₂N groups in 1-methoxy-1-methyl-, 1,1-dimethoxy-, 1-diethylamino-1-methyl-and 1,1-bis(diethylamino)-1-silacyclobutanes to form dimethylaminoethoxy derivatives. Triethanolamine and N,N-bis(2-hydroxyethyl)glycinamide split the silacyclobutane ring in 1,1-dimethoxy-1-silacyclobutane to form 1-propylsilathrane and 1-propyl-2-azasilathran-3-one, respectively.     

Stereochemical preference of Candida parapsilosis ATCC 7330 mediated deracemization: E- versus Z-aryl secondary alcohols

The stereochemical preference of the biocatalyst, Candida parapsilosis ATCC 7330, was investigated with respect to the E/Z configuration in the deracemization and the asymmetric reduction of aryl secondary alcohols and prochiral ketones, respectively. The biocatalyst preferred the E-isomers over Z-isomers as substrates as evidenced from the experimental results of >99% ee and up to 86% isolated yield for E-secondary alcohols. The synthesis of enantiomerically pure E-4-phenylbut-3-ene-1,2-diol (ee >99%, isolated yield 86%) by whole cell mediated deracemization is reported here for the first time. The geometric preference of the enzymes was confirmed by using the cell free extract of this biocatalyst. Mechanistic insights using in silico studies showed that the E-isomers when located in the active site are favourably placed with respect to the catalytic triad (Ser-Tyr-Lys) for hydride transfer from NADPH.     

Diastereoselective synthesis of vicinal amino alcohols

The vicinal amino alcohol is a common motif in natural products and pharmaceuticals. Amino acids constitute a natural, inexpensive, and enantiopure choice of starting material for the synthesis of such functionalities. However, the matters concerning diastereoselectivity are not obvious. This Perspective takes a look in the field of diastereoselective synthesis of vicinal amino alcohols starting from amino acids using various methods.     

Basicity of some aralkyl amino alcohols

Conclusions The thermodynamic ionizaton constants of 12 amino alcohols and 4 tertiary amines were determined in 50% aqueous ethanol medium at 20°. The relation between the basicity and the structure of the investigated compounds was discussed.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 7, pp. 1683–1685, July, 1973.     

Stereochemical studies—XVII: Cyclic aminoalcohols and related compounds—IX synthesis and NMR study of stereoisomeric cis- and trans-tetramethylene- and pentamethylene-1,3-oxazine-2-ones

Isomeric tetramethylene- and pentamethylene-1,3-oxazine-2-ones (9–12 and13–16) have been synthesized, derived from cis- and trans-2-aminomethylcyclohexanol (1,2), cis- and trans-2-hydroxymethylcyclohexylamine (3,4) and from the corresponding cycloheptane analogues (5–8), respectively. The stereospecific synthesis of the aminoalcohols5–8 is described. A comparative NMR analysis of13–16 and the tetramethylene analogues (9–12) is given.     

Deuterium isotope effects in 13C NMR spectroscopy: Stereochemical assignment of monodeuteriated allylic alcohols.

Vicinal deuterium isotope effects on 13C NMR chemical shifts, ³ΔC (Φ) are given for ten monodeuteriated allylic alcohols. The relationship found for nine of them: 3ΔC(0°) ≅ 5/3 x ³ΔC(180°) allows the stereochemical assignement of their deuterium labeling. This assignment is in agreement with that from the Karplus-type relationship of vicinal coupling constants, ³J_C-D(Φ).     

Stereospecific rearrangements during the synthesis of pyrrolidines and related heterocycles from cyclizations of amino alcohols with vinyl Sulfones

Conjugate additions of amino alcohols derived from alpha-amino acids to vinyl sulfones, followed by N-benzylation, chlorination, and intramolecular alkylation, provide a convenient route to substituted pyrrolidines. The process is accompanied by the stereospecific rearrangement of substituents from the alpha-position of the amine to the beta-position of the product and takes place via the corresponding aziridinium ion intermediates. Another type of rearrangement was observed during the reaction of (2-piperidine)methanol or 2-(2-piperidine)ethanol with phenyl trans-1-propenyl sulfone, in which the methyl group appears to migrate from the beta- to the alpha-position of the sulfone moiety. This process involves the isomerization of phenyl trans-1-propenyl sulfone to phenyl 2-propenyl sulfone by the addition-elimination of catalytic benzenesulfinate anion to the former vinyl sulfone, followed by conjugate addition of the amino group to the latter sulfone. Chlorination and intramolecular alkylation then afford the corresponding rearranged indolizidine and quinolizidine derivatives, respectively.     

Enantioselective binding of amino acids and amino alcohols by self-assembled chiral basket-shaped receptors

Amino acid appended diphenylglycoluril-based chiral molecular receptors 2 and 3 have been prepared and their aggregation has been studied in water at various pH's and in chloroform. The binding of several biologically relevant guests with aromatic moieties to these aggregates has been studied with UV-Vis spectroscopy in competition experiments with 4-(4-nitrophenylazo)resorcinol (Magneson) and 2-(4-hydroxyphenylazo)benzoic acid (HABA) as probes. Aggregates of chiral host 2b showed binding of catecholamines and aromatic amino acids in an aqueous environment, as well as discrimination between amino acid enantiomers, and can be considered a mimic for adrenergic receptors.     

About diastereoselective oxidations of ferrocenyl amino alcohols

Oxidation of some 2-(N,N-dimethylaminomethyl)ferrocenylalkylcarbinols by MnO₂ is totally diastereoselective: only one diastereomer is oxidized. A study was performed to highlight the influential factors of this phenomenon. Several ferrocenyl alcohols have been studied. First, two diastereomers of the ferrocenyl amino alcohol bearing a deuterium as an R group have been synthesized and oxidized. The good reactivity of both diastereomers displayed the importance of the size of the alkyl group, which needs to be bulkier than a deuterium. The synthesis and the oxidation of endo- and exo-α-hydroxy [4](1,2)ferrocenophane enabled the elimination of the hypothesis involving the spatial position of the hydroxy group, while the two diastereomers were oxidized. The replacement of the dimethylamino group by a methoxy or a methyl, the oxidation of these compounds, and the study of the preferential conformation of each diastereomer showed clearly the influence of an intramolecular hydrogen bond. So,the diastereoselectivity was shown to depend on the steric bulk of the alkyl group and on the presence of a strong intramolecular hydrogen bond between the hydroxy group and the nitrogen.