Ethyl Cis Research Articles

First Stereoselective Synthesis of Diethyl cis- and trans-(4-Hydroxy-1,2,3,4-tetrahydroquinolin-2-yl)phosphonates and Ethyl Phenylphosphinates from Quinolin-4(1H)-one

AbstractWe report a practical method for the first stereoselective synthesis of diethyl cis- and trans-(4-hydroxy-1,2,3,4-tetrahydroquinolin-2-yl)phosphonates, as well as ethyl cis- and trans-(4-hydroxy-1,2,3,4-tetrahydroquinolin-2-yl)phenylphosphinates. The main feature of this method is the regioselective 1,4-phosponylation to N-Cbz quinolin-4(1H)-one using diethyl phosphite or ethyl phenylphosphinate followed by a highly diastereoselective reduction to give the cis stereoisomers as favored products, which were converted into trans stereoisomers through the Mitsunobu reaction. Cleavage of the N-Cbz bond under hydrogenolysis gave the target heterocyclic α-aminophosphonates and α-aminophosphinates.

Candida antarctica lipase B-catalyzed reactions of β-hydroxy esters: Competition of acylation and hydrolysis

Abstract The ester function of ethyl cis-(±)-2-hydroxycyclopentane-1-carboxylate [(±)-1] and ethyl (±)-5-hydroxycyclopent-1-enecarboxylate [(±)-2] was demonstrated to undergo hydrolysis, as a side-reaction, during asymmetric (E > 200) O-acylation with Candida antarctica lipase B (CAL-B) as catalyst and vinyl acetate as acyl donor in t-BuOMe at 30 °C. This competition of acylation and undesirable hydrolysis draws attention to CAL-B-catalyzed non-hydrolytic resolutions where the substrates contain any hydrolysable functions. Enantiomerically enriched cis-2-hydroxycyclopentane-1-carboxylic acid (ee = 90%) and 5-hydroxycyclopent-1-enecarboxylic acid (ee = 47%) were prepared through de novo CAL-B-catalyzed hydrolysis of (±)-1 and (±)-2 with added H2O in t-BuOMe at 30 °C.

ChemInform Abstract: Synthesis and Mesomorphous Properties of Some Derivatives of Ethyl cis- 2,6-Dimethyl-2-cyclohexen-4-one-1-carboxylate.

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Stereospecific microbial reduction of ethyl 1-benzyl-3-oxo-piperidine-4-carboxylate

Microbial reduction of ethyl 1-benzyl-3-oxo-piperidine-4-carboxylate by the majority of evaluated microorganisms gave the ethyl cis-(3 R,4 R)-1-benzyl-3 R-hydroxy-piperidine-4 R-carboxylate as the major product in high diastereo- and enantioselectivities. The 3 R,4 R-hydroxy ester was produced in 97.4% diastereomeric excess (de) and 99.8% enantiomeric excess (ee) by Candida parapsilosis SC16347, while 99.5% de and 98.2% ee were obtained from reduction by Pichia methanolica SC16415. A few of the evaluated microorganisms gave 10–40% of the ethyl trans-(3 R,4 S)-1-benzyl-3 R-hydroxy-piperidine-4 S-carboxylate as the minor product.

A combined experimental and computational strategy in the assignment of absolute configurations of 4-methyl-5-oxo-tetrahydrofuran-3-carboxylic acids and their esters

Enantiopure cis- and trans-4-methylparaconic acids and their alkyl esters were synthesized by a procedure involving the kinetic enzymatic resolution of diastereomeric lactonic esters. Thus, ethyl cis- and trans-4-methyl-5-oxo-tetrahydrofuran-3-carboxylates were isolated, at high conversion values, with 99% ee from the hydrolyses with HLAP and α-CT, respectively. The corresponding enantiopure cis- and trans-lactonic acids were also obtained. The absolute configurations of the products were assigned by chemical correlation, by analysis of their circular dichroism spectra and by electronic structure calculations. All three methodologies lead to the same assignment for the species considered, another example of successful interplay between experiment and theory.

Enzyme-catalyzed kinetic resolution of piperidine hydroxy esters

The highly enantioselective ( E >200) kinetic resolution of (±)-ethyl cis-(±)- 4 and trans-1-( tert-butoxycarbonyl)-4-hydroxypiperidine-3-carboxylate (±)- 5 was achieved by Pseudomonas fluorescens lipase-catalyzed asymmetric acylation with vinyl acetate in diisopropyl ether at room temperature. Candida antarctica lipase A-catalyzed asymmetric acylation of (±)-ethyl cis-1-benzyl-3-hydroxypiperidine-4-carboxylate (±)- 11 was performed with vinyl propanoate in diisopropyl ether at 3 °C, with good enantioselectivity ( E = 75).

Synthesis of Ethyl cis- and trans-4-Chloro-5-oxo-1,2-diphenylpyrrolidine-2-carboxylate

Ethyl cis- and trans-4-chloro-5-oxo-1,2-diphenylpyrrolidine-2-carboxylate have been synthesized by the cyclization of ethyl N-(α,β-dichloropropionyl)-N-phenyl-α-aminophenylacetate.

(1S,2R/1R,2S)‐Aminocyclohexyl Glycyl Thymine PNA: Synthesis, Monomer Crystal Structures, and DNA/RNA Hybridization Studies.

AbstractFor Abstract see ChemInform Abstract in Full Text.

(1S,2R/1R,2S)-ainocyclohexyl glycyl thymine PNA: synthesis, monomer crystal structures, and DNA/RNA hybridization studies.

[structure: see text] The synthesis of ethyl cis-(1S,2R/1R,2S)-2-aminocyclohex-1-yl-N-(thymin-1-yl-acetyl) glycinate (10a and 10b) via enzymatic resolution of the key racemic intermediate trans-2-azido cyclohexanols 3 is reported. The crystal structures of 10 show equatorial disposition of the tertiary amide group, with the torsion angle beta in the range 60-70 degrees. The PNA oligomers incorporating these show differential effects in hybridizing with complementary DNA and RNA.

Palladium(0)-catalyzed allylation of highly acidic and non-nucleophilic arenesulfonamides, sulfamide, and cyanamide. I.

Arenesulfonamides, sulfamide, and cyanamide are efficiently allylated using allylic carbonates under Pd(0)-catalysis. N-Arenesulfonyl-2,5-dihydropyrroles are obtained by ruthenium-mediated ring closing metathesis of the corresponding N-diallylated compounds. A stereochemical study of the reactions of ethyl cis-(5-methyl-2-cyclohexenyl) carbonate with 2,4,6-triisopropylphenylsulfonamide was performed, clean overall retention of configuration being found with bidentate phosphines.

Regioselective synthesis of ceralure B 1 and A, ethyl cis-(and trans-) 5-iodo- trans-2-methylcyclohexane-1-carboxylate

Reaction of trans-2-methyl-6-oxabicyclo[3.2.1]octan-7-one with trimethylsilyl iodide, generated in situ, followed by refluxing with ethanol gives regioselectively ethyl cis-(and trans-) 5-iodo-2-methylcyclohexane-1-carboxylate, a persistent attractant for male Mediterranean fruit flies.

Substituent effects on the 13C NMR spectra of ethyl cis‐ and trans‐2‐(p‐substituted‐phenyl)‐1‐cyclopanecarboxylates

Abstract13C NMR spectra were measured for a series of ethyl cis‐ and trans‐2‐(p‐substituted ‐ phenyl) ‐ 1 ‐ cyclopropanecarboxylates. The effects of the para substituents and the geometry on the chemical shifts are discussed.

Saturated heterocycles, 137 : Synthesis and steric structure of stereoisomeric 2- [formula omitted]-nitrophenylperhydroquinazolin-4-ones

Ethyl cis - and trans -2-aminocyclohexanecarboxylate ( 4) were used as starting material to prepare ( r -4a, t -2,_ t -8a)-, ( r -4a, c -2, c -8a)- and ( r -4a, t -2, c -8a)-2-p-nitrophenylperhydroquinazol-in-4-one and their 3-methyl-substituted derivatives in stereospecific or stereoselectlve syntheses. The relative configurations of the quinazolones were assigned via DNOE measurements. Crystal structure determinations of cis - 7a and cis - 8a were also performed by X-ray diffraction.

Synthesis of optically active cyphenothrin-14C. 14C-labelling at the carbonyl carbon.

Optically active cyphenothrins, a-cyano-3-phenoxybenzyl (1R) -cis- and (1R) -trans-chrysan-themates were labelled with 14C at the carbonyl carbon for use in metabolic studies. Ethyl glycinate-1-14C hydrochloride (6), prepared from potassium cyanide-14C (2) in the three steps, was condensed with 2, 5-dimethyl-2, 4-hexadiene via the diazo intermediate to give ethyl cis, trans-chrysanthemate-14C (7) . Hydrolysis of the ester 7 followed by geometrical separation gave cis-and trans-chrysanthemic-14C acid (8a and 8b) . Each geometrical isomer (8a or 8b), was optically resolved to afford (1R) -cis- or (1R) -trans-chrysanthemic-14C acid (8c or 8d) . Esterification of 8c and 8d with a-cyano-3-phenoxybenzyl bromide (9) gave (1R) -cis-and (1R) -trans-eyphenothrin- (carbonyl-14C) (la and 1b) in the yields of 4 and 6% from 2, respectively.

Study of alicylic ethyl cis- and trans-2-hydroxycarboxylates by gas chromatography

The structure and conformation of alicylic cis- and trans-2-hydroxycarboxylates were studied by gas chromatography. As these substances serve as starting materials for the synthesis of stereospecific alicylic compounds, it was of major importance to establish the stereochemical uniformity of each isomer. Further, the study of the structure and conformation of the iosmers was important per se, as these compounds, containing hydroxy and carbethoxy groups in vicinal positions, are prone to form intramolecular and intermolecular hydrogen bonds. Gas chromatography was the method of choice for the study of these hydrogen bonded structures.

Preparation of cis,cis‐, trans,cis‐, cis,trans‐ and trans,trans‐12,15‐octadecadienoic‐9,10‐d2 acids, methyl esters and triglycerides

AbstractMethyl cis,cis‐, trans,cis‐, cis,trans‐, and trans,trans‐12,15‐octadecadienoates‐9,10‐d2 were prepared by the Wittig Reaction between cis‐ or trans‐3‐hexenyltriphenylphosphonium bromide and methyl 12‐oxododecanoate‐9,10‐d2 with butyl lithium in ethyl ether. At room temperature, the Wittig Reaction gave a product mixture with 80‐85% cis geometry in the double bond formed. When the reaction was run at −40°C, followed by protonation with methanol and slow warm‐up to room temperature, the product mixture had 60‐65% trans geometry in the double bond generated. Mixtures of the cis,cis and trans,cis and of the cis,trans and trans,trans isomers were separated by partial silver resin chromatography, and the individual pure fatty esters were converted to the triglycerides through the respective acid chlorides. Melting points and nuclear magnetic resonance chemical shifts are presented.

Vinyl anions. Part 9. Vinyl carbanions derived from acrylic esters and their β-phenyl derivatives

Ethyl ββ-diphenylacrylate, ethyl cis- and trans-cinnamate, methyl and ethyl maleate, ethyl fumarate, and methyl acrylate were treated with a strong base at low temperatures to yield the derived vinyl carbanions. The vinyl carbanions were treated with various electrophiles to give the corresponding α-substituted derivatives. Ethyl cis- and trans-cinnamate gave mostly β-substituted products having trans-geometry. The products obtained from the maleic esters were the corresponding fumarate derivatives. Deuteriation of ethyl cis-cinnamate gave the α-deuteriated ethyl cis-cinnamate. In the absence of an added electrophile dimers and trimers were isolated in the case of ethyl cis- and trans-cinnamate. Solvent, base, and temperature effects were also studied.

ChemInform Abstract: MEDICINAL CHEMICAL STUDIES ON ANTIPLASMIN DRUGS. V. 4‐AMINOMETHYLCYCLOHEXANECARBOXYLIC ACID DERIVATIVES HAVING A METHYL GROUP AT C2 OR C3

AbstractAuf dem im Formelschema angegebenen Weg werden die Aminomethyl‐methylcyclohexancarbonsäuren (III), (IV), (IX) und (X) hergestellt.

Medicinal chemical studies on antiplasmin drugs. V. 4-Aminomethylcyclohexanecarboxylic acid derivatives having a methyl group at C2 or C3.

Four isomers of 4-aminomethyl-2-methylcyclohexanecarboxylic acid (9) were synthesized from 4-cyano-o-toluic acid (2) or cis or trans 2-methyl-4-oxocyclohexanecarboxylic acid (5), and the isomers of 4-aminomethyl-3-methylcyclohexanecarboxylic acid (23) were also synthesized from 4-cyano-m-toluic acid (13) or ethyl cis or trans 7-methyl-1, 4-dioxaspiro [4. 5] decane-8-carboxylate (15). The configurations of these isomers were determined on the basis of those of the starting materials and by leading them to dimethyl 2-methylcyclohexane-1, 4-dicarboxylate (12), which was compared with 12 obtained from 5-methylbicyclo [2. 2. 2] oct-2-ene (10). The preferred conformations of the isomers in aqueous solution were deduced from the nuclear magnetic resonance spectra. The antiplasmin activity of t-4-aminomethyl-c-3-methyl-r-1-cyclohexanecarboxylic acid (23B), which is thought to exist in the 1-e, 3-e, 4-e form in aqueous solution, and which was the most active among the compounds tested in this study, was only about 0.64 times that of trans 4-aminomethylcyclohexanecarboxylic acid (1B).

Studies on keten and its derivatives. Part 88. Ethyl 5-oxo-4-oxaspi ro[2,3]hexane-1-carboxylate : synthesis and reactions

Photoreaction of diketen with ethyl diazoacetate gave ethyl cis- and trans-5-oxo-4-oxaspiro[2,3]hexane-carboxylate (1). Ethanolysis of compound (1) with hydrogen chloride at room temperature gave diethyl 3-oxohexane-1,6-dioate (4). Heating of compound (1) with sodium hydroxide in ethanol gave 5-ethoxycarbonyl-4-oxopentanoic acid (5). Reaction of (1) with phenols gave the coumarin derivatives (7a and b). Reaction of (1) with anilines gave the 5-carbamoyl-4-oxopentanoate derivatives (2c and d). Compound (1) reacted with phenylhydrazine, hydroxylamine, and acetamidine to give the pyrazolone (10), isoxazolone (11), and pyrimidone derivative (12), respectively.