Ethylthio Group Research Articles

Thioether-Assisted Cu-Catalyzed C5-H Arylation of Imidazo[1,5-a]pyridines.

A Cu-catalyzed regioselective C5-H arylation of imidazo[1,5-a]pyridines with aryl iodides was achieved with the assistance of an ethylthio group at the C3 position. This directing group could be easily removed to furnish a range of 5-(hetero)arylimidazo[1,5-a]pyridine derivatives. The reaction tolerates a variety of functionalities and is compatible with sterically hindered substrates.

ChemInform Abstract: Broensted Acid‐Mediated Annulation of α‐Oxo Ketene Dithioacetals with Pyrroles: Efficient Synthesis of Structurally Diverse Cyclopenta[b]pyrroles.

AbstractThe annulation of dithioacetals with pyrroles is accompanied by a migration of the ethylthio group to afford cyclopenta[b]pyrroles such as (III) and (VIII), which are converted into sulfones (IV) and (IX), resp., using MCPBA as oxidant.

Pore surface engineering in a zirconium metal–organic framework via thiol-ene reaction

A porous olefin-functionalized Zr(IV)-based metal–organic framework, denoted as UiO-68-allyl, has been constructed. Our results clearly demonstrated that the surface of UiO-68-allyl could be decorated with organic molecule (ethanethiol) via thiol-ene reaction. More importantly, the crystallinity of the framework were maintained during the post-synthetic modification process. However, the microporosity of the framework is retained but the surface area decreased, due to the grafting of ethylthio groups into the pores. From our studies, we can conclude that the strategy of post-synthetic modification of UiO-68-allyl via thiol-ene reaction may be general. Furthermore, we may anchor other desired functional group onto the pore walls in Zr-MOFs via thiol-ene reaction, enabling more potential applications.

Synthesis of N6-alkyl(aryl)-2-alkyl(aryl)thioadenosines as antiplatelet agents

A series of novel N6-alkyl(aryl)-2-alkyl(aryl)thioadenosines were synthesized, and their human antiplatelet aggregation activities were evaluated by the stimulation of adenosine 5′-diphosphate (ADP). Some of these compounds showed strong activity, among which compound 5b11 displayed the highest activity with an IC50 value of 29±3μM. Furthermore, five compounds were tested against arachidonic acid (AA)-induced human platelet aggregation. The results showed that compound 5b10 exhibited the highest activity with an IC50 value of 3±2μM. The adenosine derivatives substituted with a phenethyl group at the N6 position and a methylthio or ethylthio group at the C-2 position displayed high antiplatelet aggregation activity.

Synthesis of the four 1-(1-deoxy- d-pentitol-1-yl)thymines and conformational properties of the acyclic sugar chain

Acetylated d-pentose diethyl dithioacetals were coupled by way of 1-bromo-1-ethylthio derivatives with 2,4-bis(trimethylsilyl)thymine to afford diastereomeric pairs of acyclic-sugar nucleoside analogues bearing a thymin-1-yl and an ethylthio group at C-1. Free-radical desulfurization by the action of tributylstannane removed the ethylthio group to afford the corresponding acetylated 1-(1-deoxy- d-pentitol-1-yl)thymines and subsequently the free title compounds in the arabino, lyxo, ribo, and xylo series. Conformations of the intermediates and products were studied in detail and the final products were evaluated for their potential as agents active against plant viruses and rice blast fungus.

Vinylic nucleophilic substitution in functionalized 2-vinylpyrroles: a route to a new family of stable enols

2-(2-Cyano-1-ethylthioethenyl)pyrroles easy exchange their ethylthio group for hydroxyl (NaOH, H 2O–methanol, 40–45 °C, 1 h) to give 2-(2-cyano-1-hydroxyethenyl)pyrroles, a new family of stable enols, in 50–94% yields. The vinylic nucleophilic substitution proceeds at the double bond of both the starting pyrroles and their cyclic isomers, 3-iminopyrrolizines. X-ray structure analysis and NMR spectra show the enols to be stabilized by exceptionally strong intramolecular H-bonding.

Transformation of acetalized polyhyroxyketene thioacetal in acid-alcohol medium

2,3:4,5-Di-O-cyclohexylidene-L-arabinose diethyl dithioacetal was treated with sodium methylsulfinylmethylide to prepare a novel compound, 4,5-cyclohexylidene-2-deoxy-L-erythro-pent-1-enose diethyl dithioacetal. The product undergoes a series of transformations in anhydrous ethanol in the presence of p-toluenesulfonic acid: alcoholysis of the cyclohexylidene protection, elimination of water, migration of the double bond, formation of an acyclic allyl cation, elimination of the ethylthio group, formation of a cyclic allyl cation, migration of the mercapto group from C1 to C3,addition of alcohol, and formation of an acetalized lactone. The latter was acetalized to obtain a diastereomeric mixture of 5-O-acetyl-2-deoxy-3-S-ethyl-L-threo- and -erythro-pentono-1,4-lactones.

Acylation of Cyclopropyl-Substituted Alkenes with Complexes Formed by ω-(Ethylthio)alkanoyl Fluorides and Boron Trifluoride

Cyclopropyl-substituted alkenes react with complexes formed by boron trifluoride and 3-(ethylthio)propionyl fluoride and 2-(ethylthio)acetyl fluoride to give ketones containing an ethylthio group. In most cases the reaction is not accompanied by opening of the three-membered ring or rearrangements.

Utility of a diene–tricarbonyliron complex as mobile chiral auxiliary: iterative use for constructing contiguous chiral centers

Three stereogenic centers bearing azide, methoxy, and ethylthio groups, have been constructed stereoselectively using the sole chirality of the Fe(CO)3 group with concurrent 1,2-migration of the Fe(CO)3 group and the obtained product was converted to an anti-aminoalcohol derivative to determine the absolute stereochemistry.

Regioselective Synthesis of L-Idopyranuronic Acid Derivatives: Intermolecular Aglycon Transfer of Dithioacetal Under Standard Glycosylation Conditions

C-1-thioacetalization of L-idofuranurono-6,3-lactone followed by regioselective p-methoxybenzylidenation at C-2 and C-4 gave the hydroxylactones 4 and 19, which were protected at C-5 with TBDMS. Lactone ring opening with methylamine followed by regioselective reductive cleavage of the 1,3-dioxane furnished acceptors 9 and 24. Intermolecular ethyl and phenyl thio group transfers were observed during the attempted preparation of disaccharide 35 through coupling reactions of either 9 or 24 with trichloroacetimidate donor 33, leading to the formation of thioglycoside of donor 33 and the thioglycoside of acceptors 9 or 24 in the furanose form. This intermolecular aglycon transfer was investigated under various glycosylation conditions. Finally, the free 4-hydroxyl groups in acceptors 9 and 24 were acetylated. Desilylation at C-5 followed by ring closure with mercuric salts afforded, in both cases, the IdopA donor and/or acceptor precursor 16.

N-Hexyl-N-phenyl-5-ethylthioindole-2-carboxamide

Knowledge of the position of the ethylthio group in the title compound, C 23 H 28 N 2 OS, allows generalization of the behaviour of two families of indoles undergoing alkylthiolation reactions. The 'H NMR spectrum of this compound is in agreement with that recently observed for other 1-carboxamide indole derivatives. The structure and conformation of the molecule is discussed and compared with that of the analogous compound N-methyl-N-phenyl-2-(5-methoxyindole)carboxamide.

Cationic ring‐opening polymerization behavior of 2‐ethenyl‐4‐methylene‐1,3‐dioxolane

AbstractThe cationic ring‐opening polymerization of 2‐ethenyl‐4‐methylene‐1,3‐dioxolane (3) was carried out. The unsaturated cyclic acetal 3 was prepared by dehydrochlorination of 4‐chloromethyl‐2‐ethenyl‐1,3‐dioxolane, which was readily obtained from acrolein and epichlorohydrin, with sodium methoxide at ambient temperature. The cationic polymerization of 3 with BF3OEt2 or CF3SO3H at −78°C afforded cross‐linked polymers, whereas the polymerization by CH3SO3H gave a soluble poly(keto‐ether) which consisted of a unit containing a carbon‐carbon double bond in the side chain (unit 4) and a unit containing a vinyl ether group in the main chain (unit 5). The reaction of 3 with ethanethiol in the presence of a protic acid was also carried out as a model reaction of the polymerization. The reaction was initiated by addition of a proton to the 4‐methylene group of 3, followed by quantitative ring‐opening isomerization to afford acyclic ketones containing the ethylthio group. On the basis of the model reaction, some speculation on the polymerization mechanism is disclosed.

Kinetic and equilibrium studies of σ-adduct formation and nucleophilic substitution in the reactions of ethyl thiopicrate with aliphatic amines in dimethyl sulfoxide

Kinetic and equilibrium results are reported for the reaction of ethyl thiopicrate with butylamine, pyrrolidine and piperidine in dimethyl sulfoxide. The most rapid reaction involves attack at the unsubstituted 3-position to give anionic σ-adducts. The rate-limiting step in this process changes from nucleophilic attack by amine with butylamine to proton transfer from the zwitterionic intermediate with piperidine; pyrrolidine shows intermediate behaviour. Attack by amine at the 1-position results in displacement of the ethylthio group, although intermediates are not observed during this process. It is suggested that base catalysis observed in the reaction with pyrrolidine may result from rate-limiting proton transfer from the zwitterionic intermediate. 1H NMR measurements using 0.1 mol dm–3 solutions of substrate show that the displaced ethanethiolate ion may attack ring-carbon atoms of either unreacted substrate or substitution products.

Incidence and avoidance of stereospecific 1,2-ethylthio group migration during the synthesis of ethyl 1-thio-α- l-rhamnopyranoside 2,3-orthoester

The 1,2-migration of an ethylthio group with inversion of configuration at the C-1 and C-2 atoms was observed during the attempted preparation of 2,3-orthoester derivatives of ethyl 1-thio-α- l-rhamnopyranoside. The rearrangement leading to the formation of methyl 2-thio-β- l-glucopyranosides could be avoided by preparing the orthoester in DMF rather than in acetonitrile and by using a controlled amount of acid catalyst.

Formation of thienothiophenes in the high temperature reaction of 2-chlorothiophene with compounds containing the c2h5s group

The high temperature gas-phase reaction of 2-chlorothiophene with a mixture of diethyl disulfide and diethyl trisulfide constitutes a simple one-step synthesis of a 4∶1 mixture of thieno[2,3-b]- and thieno[3,2-b]-thiophenes. Their total yield depends on the nature of the donor of the ethylthio group.

ChemInform Abstract: Reaction of Trivalent Phosphorus Thioesters with Complex Hydrides of Alkali Metals.

AbstractThe ethylthio groups of the trivalent P‐esters (I) and (III) are substituted by hydrogen upon reaction with lithium aluminum hydride, thus producing the phosphines (II) and (IV).

5-Ethylthiomethyl- und 5-Ethylsulfonylmethylpyrimidine

In 2,4-dichloro-5-ethylthiomethylpyrimidines3a, b and in (2,4-dichloro-5-pyrimidinylmethyl)ethyl sulfones5a, b, resp., by reaction with ammonia, diethyl-amine, isopropylamine, sodium methanolate and sodium ethylthiolate, resp., the halogen atoms have been substituted by amino, methoxy or ethylthio groups, resp., and thus the compounds4a–4r and5c–5f have been obtained.

Chemical consequences of the intramolecular interaction between a sulphur atom and a methoxycarbonyl group in fluorene systems

The intramolecular interaction between a sulphur atom and a methoxycarbonyl group was found to affect their chemical reactivity. The rates of C–S bond cleavage in methyl 9,9-bis(ethylthio) fluorene-x-carboxylate, where x is 1, 2, or 3, with sodium ethanethiolate show that the rate is minimal, though comparable with the others, when x= 1, because of steric effects. In contrast, methyl 9-(ethylthio)fluorene-x-carboxylates, where x is 1, 2, or 3, exhibit the maximum rate when x= 1. The rates of ester exchange in the presence of toluene-p-sulphonic acid indicate that the reaction is accelerated by the presence of two ethylthio groups at the 9-position of methyl fluorene-1-carboxylate but no significant effect is detected if there is only one ethylthio group. The hydrolysis of the thioketal group in 9,9-bis(ethylthio)fluorene is also accelerated by the presence of a 1-methoxycarbonyl group. The implications of these results are discussed with the use of a model compound.

A friedel-crafts synthesis of m-substituted thiophenecarbothioamides

The reaction of thiophene and 2,5-dimethylthiophene with isothiocyanates in the presence of aluminum chloride in nitromethane gave rise to the formation of the N-substituted carbothioamides of thiophene-2-carboxylic and 2,5-dimethyl-thiophne-5-carboxylic acid, respectively. Under similar conditions, 2-ethylthio-5-methylthiophene was attacked by the reagent at the carbon atom adjacent to the ethylthio group, whereas 2-phenyl-5-methylthiophene yielded a mixture of the 3 and 4-carbothioamides.

The retention of selenium chains in reversed-phase liquid chromatography

Organic polyselenides in which the selenium chains are terminated at both ends by ethyl-thio, butyl-thio, phenylthio, or phenyl groups were prepared. Their chromatographic behavior in HPLC on a bonded octadecyl phase with entirely or mainly methanolic eluents was investigated and compared with the corresponding polysulphides. The retention increment per Se atom is greater than that for S atoms. The ratio of Se to S increments is equal to the ratio of surface area increments. The S−Se bond does not have an appreciable influence on retention. Bonded to phenyl, selenium increases retention to the same extent as sulphur does. Some of the RSSenSR solutes were identified by mass spectrometry and other techniques.