Synthesis and structure of amino esters of menthol

The conditions for the acylation of (?)-menthol with monochloroacetyl chloride have been studied. Amino esters of (?)-menthol have been obtained by the nucleophilic replacement of the chlorine in (?)-menthol monochloroacetate by residues of secondary amines. Their properties and their mass, IR, and¹³C NMR spectra are described.     

Synthesis,antimicrobial activity,and structure–activity relationships of eugenol,menthol, and genistein esters

This study concentrates on the extraction of eugenol, menthol, and genistein, and the synthesis, antimicrobial activity, and structure-activity relationships of their ester derivatives. The esters were tested for antimicrobial activity against several bacteria and yeast, and the correlation between biological properties and various physicochemical properties was examined. The ester derivatives gave intense emissions upon irradiation by UV light and have photoluminescence quantum yields of 39, 35, and 36% and long excited-state lifetimes of 3.62, 3.23, and 3.40 ns, respectively. These esters may be used in herbal medicinal therapy, and additionally as a base for the development of new drugs for phytomedicine.     

Synthesis and characterization of novel amino cellulose esters

The homogeneous conversion of cellulose dissolved in N-methyl-2-pyrrolidone/LiCl and 1-N-butyl-3-methylimidazolium chloride with N-methyl-2-pyrrolidone, ε-caprolactam, N-methyl-ε-caprolactam, and N-methyl-2-piperidone in the presence of p-toluenesulphonic acid chloride was studied. Depending on the reaction conditions, novel cellulose esters with degree of substitution (DS) values ranging from 0.12 to 1.17 could be prepared. The structure of the amino group containing cellulose esters was elucidated by elemental analysis, FTIR- and NMR spectroscopy. NMR spectroscopy revealed an almost complete esterification of position 6 of the anhydroglucose unit at DS of 1. The conversion can be conducted between room temperature and 40 °C, while side-reactions became predominant at 60 °C. Starting with DS of 0.24, the samples were soluble both in water and dimethyl sulphoxide. The derivatives described are capable of forming polyelectrolyte complexes. The samples were stable at room temperature in aqueous solution at pH 2 and 7. Lower viscosities were found for samples with higher DS in aqueous solution at comparable molar mass.     

Synthesis of amino acid esters by papain

A wide range of N-Boc-amino add esters were synthesized from N-Boc-amino acids and alcohol using papain as catalyst. Suitable biphasic reaction mixtures were found for most amino acids to achieve high yield of ester synthesis. With N-Boc-L-aspartic and glutamic adds only the a carboxyl group is esterified, without racemisation.     

Synthesis and properties of amino acid esters of hydroxypropyl cellulose

The amino acid esters of hydroxypropyl cellulose (HPC) [R′ = H ( 2a ), CH₃ ( 2b ), CH₂CH(CH₃)₂ ( 2c ), CH₂CONH₂ ( 2d ), CH₂CH₂CONH₂ ( 2e ), CH₂CH₂CH₂CH₂ NHOCOC(CH₃)₃ ( 2f )] were synthesized in good yield by the reaction of t‐butoxycarbonyl (t‐Boc)‐protected amino acids with hydroxy groups of HPC ( 1 ; molar substitution (MS), 4.61). The amino acid functionalities displaying varied chemical nature, shape, and bulk were utilized and the bulk of the substituent on the α‐carbon of amino acids was elucidated to be of vital significance for the observed degree of incorporation (DS_Est). The ¹H NMR spectra and elemental analysis were employed to determine the degree of incorporation of amino acid moiety (DS_Est) and almost complete substitution of the hydroxy protons was revealed for 2a , 2b , and 2f . The presence of the peaks characteristic of the carbonyl group in the FTIR spectra furnished further evidence for the successful esterification of HPC. The starting as well as the resulting polymers ( 1 and 2a – f ) were soluble in polar organic solvents; however, the esterification of 1 with bulky organic moieties resulted in an increased hydrophobicity as all of the amino acid‐functionalized polymers ( 2a – f ) were insoluble in water. The onset temperatures of weight loss of 2a – f were 175–230 °C, indicating fair thermal stability. The amino acid functionalization led to the enhanced polymer chain stiffness, and the glass transition temperatures of the derivatized polymers were 30–40 °C higher than that of 1 (T_g 3.9 °C; cf. T_g of 2a – f , 35.1–43.3 °C). © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 2326–2334, 2008     

Synthesis and structure of tetrahydro-1,2-oxazine-n-dithiocarboxylic acid esters

New tetrahydro-1,2-oxazine-N-dithiocarboxylic acid esters were synthesized, and their structures were investigated by IR and PMR spectroscopy and mass spectrometry.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 454–458, April, 1976.     

Synthesis and structure—aroma correlation of anisaldehyde oxime esters

Preparative syntheses from anisaldehyde 1 of the anti-isomer of anisaldehyde oxime 2 and anisaldehyde oxime esters 3a-q in 84-93% yields were developed. The structure—aroma correlation of 2 and 3a-q was studied. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 131-134, March-April, 2009.     

Synthesis of substituted asymmetrical biphenyl amino esters as alpha helix mimetics

As part of our ongoing project to develop new molecular probes for estrogen receptor-alpha, we are exploring the utility of internally-substituted asymmetric biphenyls as a proteomimetic scaffold. In this study, we describe synthetic methods for preparing the requisite substituted-bromophenol precursors, their further elaboration, and the subsequent Suzuki–Miyaura coupling of these sterically-hindered and electronically-rich aromatic systems. The results provide an efficient route with which to generate further libraries of novel asymmetric biphenyl compounds as potential proteomimetics.     

糖基化三氮唑水杨酸白杨素酯的合成与结构表征

根据药物拼合原理,以水杨酸为桥联基将糖基化三氮唑结构引入白杨素分子中,合成了4个糖基化三氮唑水杨酸白杨素酯衍生物,产物结构经核磁共振谱氢谱、红外光谱、质谱和元素分析确认.     

Synthesis,structure, and properties of chiral liquid crystal monomers and polymers based on menthol

To study structure–mesomorphism relationships of the monomers and polymers based on menthol, four new chiral monomers ( M₁ – M₄ ) and the corresponding homopolymers ( P₁ – P₄ ) with menthyl group were synthesized. Their chemical structures, formula, phase behavior, and thermal stability were characterized by FTIR, ¹H NMR, ¹³C NMR, elemental analyses, differential scanning calorimetry, polarizing optical microscopy, X‐ray diffraction, and thermogravimetric analysis. The selective reflection of light was investigated with ultraviolet/visible spectrometer. The influence of the mesogenic core rigidity, spacer length, and menthyl steric effect on the mesomorphism of M₁ – M₄ and P₁ – P₄ was examined. By inserting a flexible spacer between the mesogenic core and the terminal menthyl groups, four target monomers and polymers could form the expected mesophase. Moreover, their melting temperature (T_m), glass transition temperature (T_g), clearing temperature (T_i), and mesophase range (ΔT) increased with increasing the mesogenic core rigidity; whereas the T_m and T_g decreased, T_i and ΔT increased with an increase of the spacer length. M₁ and M₂ showed monotropic and enantiotropic cholesteric phase, respectively, whereas M₃ and M₄ all revealed chiral smectic C (SmC*), cholesteric and cubic blue phases. In addition, with increasing temperature, the selective reflection of light shifted to the long wavelength region at the SmC* phase range and to the short wavelength region at the cholesteric range, respectively. P₁ and P₂ only showed a smectic A (SmA) phase, whereas P₃ and P₄ exhibited the SmC* and SmA phases. All the obtained polymers had very good thermal stability. © 2012 Wiley Periodicals, Inc. J. Polym. Sci. Part A: Polym Chem, 2012     

Studies on amino acids and peptides—I : Synthesis of N-benzyloxycarbonylendo-thiodipeptide esters

N-Benzyloxycarbonylendothiodipeptide esters, 3, are synthesized without racemization from the corresponding N-benzyloxycarbonyldipeptide esters, 2, using 2,4-bis(4-methoxyphenyl)-1,3,2,4-dithiadiphosphetane 2,4-disulfide, 1, as thionation reagent. The benzyloxycarbonyl amino-protecting group (Z) is removed from 3 by using HBr-AcOH.     

Diastereoselective synthesis of aziridine esters via amino selanyl esters

A synthesis of aziridine esters based on the cyclisation of amino selanyl esters induced by the selanyl group activation was developed with either the Meerwein salt or NBS. Two asymmetric approaches are proposed: the diastereoselective reductions of α-selanyl β-iminoesters derived from α-oxoesters, which lead to cis chiral aziridine esters 6 and 6′; and the diastereoselective conjugate additions of a chiral amide to α,β-unsaturated esters providing trans chiral aziridine esters 6 and 6″.     

新型多齿手性氨基醇的合成和结构表征

以L-苯甘氨酸和N,N-二甲基苯胺为原料,合成了2种新型多齿手性氨基醇S-1,1,2-三苯基-2-[(2-二甲氨基-5-溴-1-苯基)甲氨基]-1-乙醇和S-2-苯基-2-[(2-二甲氨基-5-溴-1-苯基)甲氨基]-1-乙醇;利用红外光谱仪、核磁共振谱仪及质谱仪表征了合成产物的结构.     

Synthesis and structure of a heterocyclic ansa pyrrole amino acid

We report a synthetic route to ansa pyrrole amino acids via olefin ring-closing metathesis of diene precursors in the presence of Grubbs I catalyst. The dienes were prepared by Grignard addition to pyrrole sulfinyl imines. The success of the macrocyclic ring closure depends on the dienes structure and only in the case of the 13-membered compound 28 sufficient material could be isolated by preparative HPLC separation to investigate its structure spectroscopically. As also rationalized by our computations at the B3LYP/6-311+G(d,p)//B3LYP/6-31G(d) level of theory, 28 is configurationally stable.