Enantiopure synthesis of all four stereoisomers of carbapenam-3-carboxylic acid methyl ester

The retro-Dieckmann reaction has been used as a stereodivergent synthetic tool on N-Boc-7-azabicyclo[2.2.1]heptan-2-one-1-carboxylic acid methyl ester to obtain enantiopure trans- and cis-5-(carboxymethyl)pyrrolidine-2-carboxylic acid methyl esters. These disubstituted pyrrolidines have been used as starting materials to develop concise and straightforward syntheses of all four stereoisomers of carbapenam-3-carboxylic acid methyl esters. In this way, we have confirmed unequivocally the stereochemistry of two carbapenams isolated from strains of Serratia and Erwinia species.     

New Triterpenoid Fatty Acid Esters from the Small Twigs of Viburnum Odoratissimum

α‐Amyrin margarate ( 1 ), moretenyl margarate ( 2 ) and moretenyl palmitate ( 3 ), three triterpenoid fatty acid esters, have been isolated from the acetone extract of the small twigs of Viburnum odoratissimum in addition to the three known compounds, α‐amyrin palmitate ( 4 ), ursolic acid ( 7 ) and vibsanin‐K ( 8 ). The structures of compounds 1–3 were elucidated based on extensive spectroscopic analysis and alkaline hydrolysis. Preliminary pharmacological studies revealed that vibsanin‐K and ursolic acid exhibited significant cytotoxicity against human gastric (NUGC) and oral epidermoid (HONE‐1) tumor cells at a concentration of 50 μg/mL while compounds 1–3 were inactive.     

HPLC of fatty acid esters of mono- and polyhydric alcohols. Part 2: Preparative separation

This paper demonstrates how simply and rapidly fatty acid esters of mono- and polyhydric alcohols can be separated quantitatively in preparative quantities on Lobar® RP-8 packed columns. After the separation of unknown mixtures, the isolated esters are identified from spectroscopic data (IR/NMR) and, after saponification of the ester components (fatty acids and alcohols), from the retention times of gas and high-pressure liquid chromatographic separations. Thus, in particular, sparingly volatile or nonvolatile partial esters of polyhydric alcohols, as well as the long-chained full esters, can be determined qualitatively and quantitatively. The following fatty acid esters of mono- and polyhydric alcohols have been separated: the i-propylesters of the laurinic and myristinic acids, the i-butyl-, i-octyl- and i-octadecyl-esters of the palmitinic and stearic acids, the mono- and di-fatty acid esters of the 1,3-bis-(2-hydroxyethyl)-5,5-dimethylhydantoins, the mono-, di- and tri-esters of the trimethylalpropane and the full esters of the pentaerythrite.     

Synthesis and reactions of esters of 3-cyano-2-OXO-5,6-tri(tetra)methylene-1,2-dihydroisonicotinic and 2-amino-3-Ethoxycarbonyl-5,6-tri(tetra)-methyleneisonicotinic acids

Esters of 3-cyano-2-oxo-5, 6-tri (tetra)-methylene-1, 2-dihydroisonicotinic and 2-amino-3-ethoxycarbonyl-5, 6-tri (tetra)methyleneisorticotinic acids have been obtained by the reaction of 2-oxocyclopentyl(hexyl)glyoxylic acid esters with malonic acid derivatives. Boiling the esters containing a tetramethylene ring with 75% sulfuric acid gave hydrolysis of the ester and cyano groups to carboxyl with subsequent decarboxylation at the 3 position and the formation of 2-oxo-5, 6-tetramethylene-1, 2-dihydroisonicotinic acid (2-oxo-1, 2, 5, 6, 7, 8-hexahydroquinoline-4-carboxylic acid).Perm Pharmaceutical Institute, Perm, 614000. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 370–373, March, 1996. Original article submitted July 10, 1995, revision submitted December 26, 1995.     

Vorkommen neuer bifunktioneller. Ester im Römisch-Kamillenöl (Anthemis nobilisL.)

Occurrence of New Bifunctional Esters In Roman Camomile Oil (Anthemis nobilis L .) Some novel aliphatic esters of the unusual 3-hydroxy-2-methylidenebutyric acid have been found in the commercially available essential oil. Additionally, esters of (Z)-2-methyl-2-butenoic acid of structurally similar diols or other bifunctional alcohols have also been identified. Spectral data as well as a synthetic approach to the new esters of 3-hydroxy-2-methylidenebutyric acid are given.     

Terpenoids and phenolics from Plectranthus strigosus, bioactivity screening

Further studies on Plectranthus sp. (Lamiaceae) led to the isolation of terpenes and phenol esters from Plectranthus strigosus Benth. ent-16-Kauren-19-ol (1), ent-16-kauren-19-oic acid (2), xylopic acid (3), xylopinic acid (4), hinokiol (5), 4 beta,6 beta-dihydroxy-1 alpha,5 beta(H)-guai-9-ene (6) 4 beta,6 beta-dihydroxy-1 alpha,5 beta(H)-guai-10(14)-ene (7), mixtures of hexacosan-1,26-diol and octacosan-1,28-diol ferulate diesters (8), of esters from ferulic acid and fatty alcohols (9) and of esters from fatty acids and 2-(4-hydroxyphenyl)-ethanol (10) were for the first time isolated from this genus. Supplementary spectral data for 3,8 and parvifloron D (11) metabolites are also presented. A bioactivity study revealed herpetic inhibitory properties for (1) and (2), and antioxidant ability for (5) and (8) phenolic constituents.     

Synthesis of unsaturated esters of pyridine-and quinolinecarboxylic acids

The vinyl esters of pyridine-2-and -4-carboxylic acids, the propargyl esters of pyridine-2-, -3-, and-4-carboxylic acids, the vinyl, allyl, and propargyl esters of quinoline-2-, -4-, and -8-carboxylic acids, and the allyl ester of 2-methylisonicotinic acid have been synthesized.     

Gas-phase reactions and rearrangements of alkyl esters with H3O+, NO+, and O2*+: a selected ion flow tube study

Selected ion flow tube mass spectrometry (SIFT-MS) has been employed to study the ion-molecule reactions of 17 alkyl esters reacting with the common SIFT-MS reagent ions, H3O+, H3O+.nH2O (n = 1, 2, 3), NO+, and O2+. The majority of reactions were observed to proceed at or near collision rate, with the exception of H3O+.3H2O, which was found to be slow for 8 of 17 alkyl esters. Unexpected product ions in the form of the parent carboxylic acid cation were observed to arise from the H3O+ and NO+ reactions of some alkyl esters. The observed reactions have been probed by the ab initio CBS-4M and G2(MP2,SVP) methods. The postulated reaction pathway involves a 1,5 H atom migration from a beta-carbon onto the carbonyl oxygen.     

The spatial structure of the isomeric dimethyl esters of 4-hydroxypiperidine-2, 6-dicarboxylic acid

Three isomeric dimethyl esters of 4-hydroxypiperidine-2, 6-dicarboxylic acid have been isolated. The spatial structures of all three isomeric esters and of the acids corresponding to them have been established on the basis of NMR spectra. It has been shown that while the isomers I and II exist in the form of only one conformation each, isomer III in neutral and acid media apparently consists of an equilibrium mixture of two (or more) conformers. The information obtained on the spatial structure of the isomeric esters shows that the cyclization of these compounds with benzylamine and p-nitrobenzaldehyde takes place with the inversion of the piperidine ring.     

peri-Dimethylamino substituent effects on proton transfer at carbon in α-naphthylacetate esters: a model for mandelate racemase

The rate constants for exchange of hydrogen for deuterium at the α-CH(2) positions of 8-(N,N-dimethylaminonaphthalen-1-yl)acetic acid tert-butyl ester 1 and naphthalen-1-ylacetic acid tert-butyl ester 2 have been determined in potassium deuteroxide solutions in 1 : 1 D(2)O : CD(3)CN, in order to quantify the effect of the neighbouring peri-dimethylamino substituent on α-deprotonation. Intramolecular general base catalysis by the (weakly basic) neighbouring group was not detected. Second-order rate constants, k(DO), for the deuterium exchange reactions of esters 1 and 2 have been determined as 1.35 × 10(-4) M(-1) s(-1) and 3.95 × 10(-3) M(-1) s(-1), respectively. The unexpected 29-fold decrease in the k(DO) value upon the introduction of a peri-dimethylamino group is attributed to an unfavourable steric and/or electronic substituent effect on intermolecular deprotonation by deuteroxide ion. From the experimental k(DO) values, carbon acid pK(a) values of 26.8 and 23.1 have been calculated for esters 1 and 2.     

Interaction of Hydroxylamine with Esters of 2-Oxobutenoic Acids. Synthesis of 1-Hydroxy-3-hydroximino-2-pyrrolidinones

New 3-hydroximino-1-hydroxy-2-pyrrolidinones have been synthesized by the interaction of NH₂OH and NH₂OBn with the methyl esters of 2-oxo-3-butenoic acid derivatives. Some intermediate compounds have been isolated and identified and the reaction mechanism is discussed.     

南海Spirasterella中脂肪酸酯组分的鉴定

用色谱—质谱联用技术分析了中国南海海绵Spirasterella aurivilli Lindgren中脂肪酸酯组分。鉴定了29种脂肪酸酯,其中20种饱和脂肪酸乙酯,8种不饱和脂肪酸乙酯及1种饱和脂肪酸甲酯。并发现该海绵中含有自然界少见的10种奇数碳脂肪酸乙酯。     

胆甾类分子钳对氨基酸衍生物的对映选择性识别

用差紫外光谱滴定法考察了以脱氧胆酸作spacer的手性分子钳1～3对一系列α-氨基酸甲酯的对映选择性识别性能。结果表明,分子钳1和2与客体氨基酸甲酯形成1:1型超分子配合物,并显示较好的手性识别能力。分钳3对所考察的氨基酸甲酯均没有明显的识别作用。讨论了主-客体间尺寸/形状匹配、几何互补等因素对形成超分子配合物的影响,并利用计算机模拟作辅助手段对实验结果和现象进行了解释。     

R(-)四氢噻唑-2-硫酮-4-羧酸对D,L-氨基酸酯拆分的研究

以新手性拆分试剂R(-)四氢噻唑-2-硫酮-4-羧酸[简称R(-)TTCA]对D,L-氨基酸酯进行手性拆分,分别得到(R)TTCA氨基酸酯盐1a_1f([α]_D²⁰＝-30.40°～-42.70°)及光学活性氨基酸酯2a-2f,其光学纯度为35.4%～75.8%.由1a_1f在碱存在下分解出2a-2f的对映体3a-3f,光学纯度为39.50%～69.10%.用半经验的量子化学PM3方法研究了氨基的碱性、中间产物铵盐生成热和稳定性.     

New phenolic constituents from the fruit juice of Phyllanthus emblica

Six new phenolic constituents, L-malic acid 2-O- (1), mucic acid 2-O- (5), mucic acid 1,4-lactone 2-O- (6), 5-O- (8), 3-O- (10), and 3,5-di-O- (11) gallates, were isolated from the fruit juice of Phyllanthus emblica together with their methyl esters (2-4, 7, 9), and their structures were determined by spectral and chemical methods. Compounds 5, 6, and 8, the major phenolic constituents of the juice, were present as an equilibrium mixture in aqueous solution.     

A spectroscopic investigation of the phenolcarboxylic acids ofCynara scolymus

Summary Spectroscopic investigations in the UV region of the phenolcarboxylic acids that we have isolated from the leaves ofCynara scolymus have been carried out. It has been found that:1. Free caffeic acid can be distinguished from its esters by the changes in the UV spectra under the influence of sodium ethoxide and sodium acetate.2. An o-dihydroxy grouping in esters can be detected from the bathochromic shift observed with boric acid in the presence of sodium acetate.3. An o-dihydroxy grouping can be detected both in esters and in the free acid under the influence of aluminum chloride.Khimiya Prirodynkh Soedinenii, Vol. 2, No. 5, pp. 303–306, 1966     

Synthesis and isomeric conversions of several 2-substituted 1,4-dihydro-4-oxo-3-quinolinecarboxylic acid derivatives

Ethyl ester derivatives of 6- and 8-substituted 2-methyl-1,4-dihydro-4-oxo-3-quinolinecarboxylic acids have been synthesized by treatment of the diethyl ester of acetylmalonic acid with 2- or 4-substituted anilines. Condensation of these newly synthesized quinolinecarboxylic acid derivatives with 4-nitrobenzaldehyde resulted in the formation of 6- and 8-substituted 2-[2-(4-nitrophenyl)-vinyl]-1, 4-dihydro-4-oxo-3-quinolinecarboxylic acids and ethyl esters of 6- and 8-substituted 2-[2-(4-nitrophenyl)vinyl]-4-acetoxy-3-quinolinecarboxylic acids. The tautomeric and conformational transformations of these newly synthesized compounds have also been investigated, using IR, NMR, and UV spectroscopy.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 931–938, July, 1988.     

Studies on the constituents of Aster scaber Thunb. III. Structures of scaberosides B7, B8 and B9, minor oleanolic acid glycosides isolated from the root.

Three new oleanolic acid 3,28-O-bisdesmosides, scaberosides B7, B8 and B9, were isolated as minor saponins from the root of Aster scaber THUNB. (Compositae), and their structures were determined based on spectral and chemical evidence as follows. Scaberoside B7 is 3-O-beta-D-glucopyranosyluronic acid oleanolic acid 28-[O-beta-D-apiofuranosyl-(1----3)-[O-beta-D-xylopyranosyl-(1---- 4)-O-alpha-L-rhamnopyranosyl-(1----2)-alpha-L-arabinopyranosyl] ester, scaberoside B8, 3-O-beta-D-glucopyranosyl oleanolic acid 28-[O-beta-D-xylopyranosyl-(1----4)-O-alpha-L-rhamnopyranosyl-(1----2)-a lpha-L-arabinopyranosyl] ester, and scaberoside B9, 3-O-beta-D-glucopyranosyluronic acid oleanolic acid 28-[O-alpha-L-rhamnopyranosyl-(1----2)-[O-beta-D-xylopyranosyl-(1----6)] -beta-D-glucopyranosyl] ester. Scaberosides B7 and B9 were obtained as their methyl esters.     

Synthesis of Insecticidally Active 3-Phenoxy Benzyl and α (RS) Cyano-3-Phenoxy Benzyl (±) Trans 2-(2, 2-Dichlorovinyl) Spiro (2,5)-Octane-1-Carboxylates

Cyclopropane carboxylic acid esters, possessing spirofused cycloallcyl rings, in place of the conven- tional gem-dimethyl group of natural pyrethrins and synthetic pyrethroids also exhibit good insecticidal I activity against a wide range of insect species. In addition, these compounds exhibit knock-down activity on flying insects. Someoc-cyan0-3-phenoxy benzyl esters of (±) - cis and (±) trans 2-(2,2-dichlorovinyl)-spiro (2,5)-octane-l-carboxylic acid and the lower spiro cycloalkyl members of the homologous series, have been synthesised and found to be active against, musca domestica, cotton leafworm etc, with good knock-down effect. The acid moieties of the above esters have been synthesised by reaction of alkyl diazo acetates on suitably substituted olefins 2, 3.     

Discovery of okadaic acid esters in the toxic dinoflagellate Dinophysis acuta from New Zealand using liquid chromatography/tandem mass spectrometry

The dinoflagellate Dinophysis acuta has been associated with various incidents of diarrhetic shellfish poisoning. A sample of Dinophysis acuta collected from New Zealand waters in 2002 was previously found to contain high levels of pectenotoxins, but only a very low level of the diarrhea-inducing okadaic acid (OA). After hydrolysis under basic conditions, however, the concentration of OA increased substantially, indicating the presence of conjugated forms of OA. Using various liquid chromatography/electrospray ionization tandem mass spectrometry (LC/ESI-MS/MS) techniques, a number of OA esters were detected in the original extract. The principal compound was identified as a C8 diol-ester of OA (OA-D8), which had been identified previously in another dinoflagellate, Prorocentrum lima. The retention time, as well as positive and negative ion MS, MS/MS and UV spectra of the D. acuta compound, matched exactly those of OA-D8 isolated from P. lima. In addition to OA-D8, several other novel OA esters were detected in the D. acuta but these have not yet been identified. This is the first report identifying the presence of OA esters in Dinophysis species.