Chain Amino Alcohols Research Articles

The control of Novozym® 435 chemoselectivity and specificity by the solvents in acylation reactions of amino-alcohols

Acylation of amino-alcohols by Novozym ® 435 (immobilized Candida antarctica lipase B). • Rates of N -acylation were higher for the short chain amino-alcohol. • Rates of O -acylation were higher for the long chains amino-alcohols. • The formation of the product was strongly affected by the nature of the solvent. The current work describes the differential behaviour of Novozym ® 435 (immobilized Candida antarctica lipase B) in O -acylation and N -acylation catalysis of bifunctional amino-alcohols acyl acceptors. We performed acylation experiments on three amino-alcohols (alaninol, 4-amino-1-pentanol and 6-amino-1-hexanol) using myristic acid as an acyl donor. Two organic solvents ( tert -amyl alcohol and n -hexane) and one ionic liquid (1-butyl-3-methylimidazolium hexafluorophosphate: Bmim [PF 6 ]) were used to determine the effect of the solvent. The influence of the amino-alcohol carbon chain length between the alcohol and amino groups on chemoselectivity C ( k cat,app O -acylation / k cat,app N -acylation ) was highlighted. N -acylation is improved using alaninol, a short chain amino-alcohol (no mono- O -acylation in tert -amyl alcohol and C = 0.12 in n -hexane) whereas O -acylation is improved using 4-amino-1-pentanol and 6-amino-1-hexanol which are amino-alcohols with longer chain ( C = 10.5 in tert -amyl alcohol and C = 539 in n -hexane). On the other hand, the production of the acylated amino-alcohols after 96 h of reaction was shown to be strongly affected by the solvent nature and the amino-alcohol structure: starting from alaninol as an acyl acceptor, the yield of amide synthesis reaches up to 98% in tert -amyl alcohol using 0.7 equivalents of myristic acid while the yield of amido-ester synthesis reaches up to 88% in Bmim [PF 6 ] using 1.75 equivalents of myristic acid.

The effect of substrate structure on the chemoselectivity of Candida antarctica lipase B-catalyzed acylation of amino-alcohols

► A nucleophilic group in β of an amino group enhances rates of N-acylation. ► The more nucleophilic group in β the higher rates of N-acylation. ► Rates of N-acylation were improved for the short chain amino-alcohol. ► Rates of O-acylation were improved for the long chains amino-alcohols. The selective acylation of multifunctional compounds exhibiting both alcohol and amino groups gives interesting products with many applications in food, cosmetic and pharmaceutical industries, but it is real challenge. The current work describes the different behavior shown by Candida antarctica lipase B (Novozym 435) when catalyzing the O-acylation and N-acylation of bifunctional acyl acceptors. The acylation of three amino-alcohols (alaninol, 4-amino-1-pentanol and 6-amino-1-hexanol) was studied using myristic acid as an acyl donor. To achieve this, a structure-reactivity study was performed in tert -amyl alcohol as a solvent, comparing the three amino-alcohols as acyl acceptors and a series of structurally related amines, namely (R)- sec -butylamine, 1-methoxy-2-propylamine and 1,2-diaminopropane. These substrates were designed to investigate the effect of the group located in β-position of the amino group on the acyl acceptor: the more nucleophilic the group, the more the apparent maximal velocity ( V max,app ) of N-acylation increases. Moreover, the crucial role of the carbon chain length between the alcohol and amino groups on the chemoselectivity was also demonstrated. The chemoselectivity for the N-acylation was improved when the carbon chain included two carbons (alaninol) whereas the chemoselectivity for the O-acylation was improved when the carbon chain included four carbons or more (4-amino-1-pentanol and 6-amino-1-hexanol). These results provided new insights for the selective synthesis of amides or esters produced from the acylation of bifunctional substrates.

ChemInform Abstract: A New Procedure for the Synthesis of C-Glycosides of Nojirimycin.

Reaction with allylmagnesium bromide of N,2,3,4,6-pentabenzyl-D-glucopyranosylamine 2, obtained from tetrabenzylglucose and benzylamine, afforded stereoselectively the open chain amino alcohol 3, which was converted into the C-glycoside of nojirimycin 6 by full protection of the amino function by Fmoc, oxidation of the free hydroxy group, hydrolysis of the Fmoc group and final intramolecular reductive amination with NaBH(OAc)3; compound 6 was also converted into methyl ketone 7, by manipulation of the allylic appendage.

Varying solvent polarity to tune the enantioselective quenching of a calixarene host

Calixarene L1 has been designed to behave as a fluorescent molecular sensor capable of distinguishing between chiral amines on the basis of their size and chirality. Fluorescence quenching studies of calixarene L1 in methanol demonstrated no enantiomeric selectivity for a short chain amino alcohol, phenylglycinol, while excellent selectivity was observed for a longer chain amino alcohol, phenylalaninol (PA). The effect of solvent on the fluorescent properties of this calixarene in the presence of PA has been studied, and demonstrates that varying solvent polarity allows the wavelength of enantiomer selectivity to be tuned from 227 nm to 440 nm. While enantiomeric selectivity is observed in methanol at 227 nm, no discrimination is achieved in acetonitrile. Chiral discrimination is statistically possible with L1 and PA in chloroform at 227 nm, but it is not comparable with the extent of discrimination achieved in methanol. In chloroform a new emission band at a longer wavelength (440 nm) is formed with R-PA in solution with L1, an effect that is not observed with the S-enantiomer. This new band in chloroform at 440 nm allows very effective chiral discrimination and has been attributed to the presence of two different conformations of calixarene L1, which is reinforced by 1H-NMR studies and molecular modelling studies.

Structure-function relations in self-assembled C18- and C20-sphingosines monolayers at gas/water interfaces.

Synchrotron X-ray studies and surface pressure versus molecular area (pi-A) isotherms of C18- and C20-sphingosines spread at air/water interfaces reveal unique interfacial properties with considerable differences between the two single hydrocarbon chain amino-alcohols. C20-sphingosine forms a crystalline monolayer with structural characteristics that are dominated by hydrogen bonding in the headgroup (common to its sphingolipid derivatives), whereas its natural counterpart C18-sphingosine forms a disordered liquidlike metastable monolayer and has to be spread in excess with a floating reservoir on the water surface to compensate for the high dissolution rate of molecules into the water subphase. The marginal affinity of C18-sphingosine to reside at the interface, the microcrystallization at very low densities, the corrugated monolayers it forms, and the strong interaction with the water surface are consistent with the roles that sphingolipids play in the life cycle of eukaryotic cells and as the building blocks of specialized membranes.

Synthesis and In vivo anti-inflammatory activity of long-chain 2-amino-alcohols

The synthesis of optically pure long-chain 2-amino-alcohols and 1- O-dodecyl-2-deoxy-2-amino- sn-glycerol was carried out starting from l- or d-Boc-Ser(OBn)-ol by oxidation and consecutive Wittig reaction or etherification reaction. 2-Amino-oleyl alcohol was synthesized by reduction of the corresponding 2-amino-oleic acid. All the long chain amino-alcohols presented interesting inhibition of carrageenin-induced paw edema in rats (ED 50 from 0.017 to 0.010 mmol/kg).

Synthesis and biological activities of long chain 2-amino alcohols

This article focuses on the synthesis and the biological activities of long chain amino alcohols. The methods for the synthesis of these sphingosine analogues from various starting materials such as lipidic amino acids, serine, glyceraldehydes, long chain 1,2-diols, are summarized in the first part of the review, followed by a discussion of the biological activities of long chain amino alcohols and the applications for the synthesis of other bioactive compounds.

A new procedure for the synthesis of C-glycosides of nojirimycin

Reaction with allylmagnesium bromide of N,2,3,4,6-pentabenzyl-D-glucopyranosylamine 2, obtained from tetrabenzylglucose and benzylamine, afforded stereoselectively the open chain amino alcohol 3, which was converted into the C-glycoside of nojirimycin 6 by full protection of the amino function by Fmoc, oxidation of the free hydroxy group, hydrolysis of the Fmoc group and final intramolecular reductive amination with NaBH(OAc)3; compound 6 was also converted into methyl ketone 7, by manipulation of the allylic appendage.

Coriacenins: A New Class of Long Alkyl Chain Amino Alcohols from the Mediterranean Sponge Clathrina coriacea

The Mediterranean sponge Clathrina coriacea contains a series of long chain amino alcohols, named coriacenins (2-6), belonging to a new class of alkaloids. The structures of the novel compounds were elucidated by studying, with a combination of spectral and chemical methods, their peracetyl derivatives (2a-6a). Coriacenins are characterized by a bis(1,3-diamino-2-propanol) moiety and a linear alkyl chain varying both by length and by degree of unsaturation. The biosynthetic pathway leading to coriacenins seems to be unprecedented. It should, however, occur through condensation of an acetogenin with an uncommon amino acid.

Solvent extraction of niobium and tantalum—VII: Extraction with di- n-octylamino alcohols from oxalic metal solutions

The extraction of niobium and tantalum with di- n-octylamino ethanol (DOAE) and di- n-octylamino propanol (DOAP) was studied from oxalic metal solutions in presence of mineral acids. The amine/metal ratio was determined in the organic phase (chloroform). The same ratio for both metals was observed, varying from 3:1 to 1:1, as dependent upon the composition of the aqueous phase. Extracting species of niobium and tantalum were separated under different conditions, and characterised by analysis and i.r. spectra. The i.r. spectra of the organic phases were examined and compared with the spectra of the separated substances. On the bases of this evidence the mechanism of the oxalato niobate and tantalate extraction with these N-substituted long chain amino alcohols is deduced, and this mechanism proved to be of the ion association type.