RESUMO
Dimethyl 2-vinylcyclopropane-1,1-dicarboxylate underwent a hydrophosphination reaction with either a primary or secondary phosphine under photolytic conditions. Notably, a free radical initiator was not required. The resulting tertiary phosphines were derivatized using S8 to afford moisture and air stable yellow or colorless oils in a 27%-73% isolated yield. A series of control reactions were performed, and we propose that this UV induced hydrophosphination reaction proceeds through a radical mechanism.
RESUMO
4-Alkynyl indoles, when treated with a benzylidene malonate or a donor-acceptor cyclopropane in the presence of a zinc halide, furnished 3,4-hexannylated or 3,4-heptannulated products, respectively, in fair to excellent yields. The reaction proceeds via a tandem addition/Conia-ene cyclization.
Assuntos
Ciclopropanos , Indóis , Catálise , Ciclização , ZincoRESUMO
Novel oxime-ether tethered cyclopropanes, when exposed to Yb(OTf)3 and heat, annulate to generate hydropyrrolo-oxazines products that can be taken to their respective pyrrolidines via hydrogenative N-O bond cleavage. The hydropyrrolo-oxazines are generated in a diastereoselective manner isolating the cis or trans product based on the temperature of the reaction. 20â examples of selective cis and trans hydropyrrolo-oxazines were generated in high yields by temperature control.
RESUMO
Cyclopropanation of 1,3-dienes with ethyl 2-formyldiazoacetate under rhodium catalysis results in either a tandem cyclopropanation/Cloke-Wilson rearrangement or a vinylogous variant, depending on the diene used. These adducts may be subjected to an oxygen to nitrogen substitution with various amines under palladium catalysis. The substrate scope and mechanistic reasoning is presented.
RESUMO
We report the total synthesis of the natural products isodihydrokoumine and (19 Z)-taberpsychine in 11 steps each and (4 R)-isodihydrokoumine N4-oxide in 12 steps from commercially available starting materials. The key reactions include an intramolecular [3 + 2] nitrone cycloaddition and Lewis acid mediated cyclizations of a common intermediate to provide the core structures of either taberpsychine or isodihydrokoumine.
RESUMO
The treatment of donor-acceptor cyclopropanes with the a strong hydrogen bond donor, HFIP, activated the cyclopropanes (via presumed hydrogen bonding) toward homo-Michael additions with indoles as the nucleophiles. This reaction proceeded without the need for high pressure or catalysis.
RESUMO
Under the influence of heat and Lewis acid, donor/acceptor cyclopropanes underwent annulation reactions with (1-azidovinyl)benzene and 3-phenyl-2H-azirine to form an unusual azabicyclic scaffold with an imbedded aziridine. The mechanism of reaction is believed to proceed via a vinyl nitrene intermediate.
RESUMO
Tandem ring opening, elimination, and cycloaddition of donor-acceptor cyclopropanes were observed in Yb(OTf)3-catalyzed cycloaddition with nitrosoarenes. The reaction results in formation of tetrahydro-1,2-oxazine instead of the normal cycloadduct isoxazolidine via in situ nitrone formation. A similar cascade sequence was observed with cis-diazines. Mechanistic studies on this unique transformation offer an entirely new approach for reaction design with donor-acceptor cyclopropanes.
RESUMO
Under the influence of Lewis acid catalysis, donor/acceptor cyclopropanes underwent nucleophilic ring opening by indolines. The resulting N-alkyl indolines bearing a pendant malonyl moiety oxidatively cyclized to 1,2-pyrroloindoles. This method was showcased by the preparation of the skeletal structure of the flinderoles.
RESUMO
Chronic kidney disease (CKD) results in the accumulation of metabolic waste products that are normally cleared by the kidney, known as uremia. Many of these waste products are from bacteria metabolites in the gut. Accumulation of uremic toxins in plasma and tissue, as well as the gut-plasma-tissue metabolic axis are important for understanding pathophysiological mechanisms of comorbidities in CKD. In this study, an untargeted metabolomics approach was used to determine uremic toxin accumulation in plasma, liver, heart and kidney tissue in rats with adenine-induced CKD. Rats with CKD were also given AST-120, a spherical carbon adsorbent, to assess metabolic changes in plasma and tissues with the removal of gut-derived uremic toxins. AST-120 decreased >55% of metabolites that were increased in plasma, liver and heart tissue of rats with CKD. CKD was primarily defined by 8 gut-derived uremic toxins, which were significantly increased in plasma and all tissues. These metabolites were derived from aromatic amino acids and soy protein including: indoxyl sulfate, p-cresyl sulfate, hippuric acid, phenyl sulfate, pyrocatechol sulfate, 4-ethylphenyl sulfate, p-cresol glucuronide and equol 7-glucuronide. Our results highlight the importance of diet and gut-derived metabolites in the accumulation of uremic toxins and define the gut-plasma-tissue metabolic axis in CKD.
Assuntos
Carbono/administração & dosagem , Falência Renal Crônica/metabolismo , Metabolômica , Óxidos/administração & dosagem , Idoso , Animais , Humanos , Falência Renal Crônica/sangue , Masculino , Análise de Componente Principal , Ratos , Ratos WistarRESUMO
This review summarizes research directed towards the formation of carbocyclic adducts from donor-acceptor cyclopropanes. The focus of the review is on annulation and cycloaddition reactions (both inter- and intramolecularly) mediated by Lewis or protic acid, bases, or thermal conditions. Rearrangements resulting in carbocycles and those reactions mediated by transition metal catalysis have been excluded.
RESUMO
Exploration into the reactivity of donor-acceptor cyclopropane hemimalonates has led to the facile synthesis of γ-substituted butanolides. Under microwave irradiation, cyclopropane hemimalonates undergo rapid conversion to butanolides in the presence of inorganic salts with an unprecedented retention of stereochemistry. This unique process has been applied to the total synthesis of the naturally occurring (R)-dodecan-4-olide.
Assuntos
4-Butirolactona/análogos & derivados , 4-Butirolactona/síntese química , Produtos Biológicos/síntese química , Ciclopropanos/química , Lactonas/síntese química , Malonatos/química , 4-Butirolactona/química , Produtos Biológicos/química , Lactonas/química , Micro-Ondas , Estrutura Molecular , EstereoisomerismoRESUMO
Treatment of indolylmethyl Meldrum's acids with catalytic scandium triflate and a variety of nucleophiles results in the nucleophilic displacement of the Meldrum's acid moiety via a gramine-type fragmentation. The reaction is useful for the generation of heterocyclic compounds of significant molecular complexity.
Assuntos
Dioxanos/química , Compostos Heterocíclicos/síntese química , Indóis/síntese química , Mesilatos/química , Escândio/química , Catálise , Compostos Heterocíclicos/química , Indóis/química , Estrutura MolecularRESUMO
Ring the changes: The cycloaddition of nitrones with 1-carboallyloxy-1-carbomethoxycyclopropanes yields tetrahydro-1,2-oxazines, which in turn undergo a Tsuji dehydrocarbonylation to give dihydro-1,2-oxazines (see scheme; dba = dibenzylideneacetone). Addition of base to this reaction mixture results in clean conversion to pyrroles. The result is a flexible three-component strategy for the synthesis of tetrasubstituted pyrroles.
Assuntos
Ciclopropanos/química , Compostos Organometálicos/química , Paládio/química , Pirróis/síntese química , Catálise , Desidratação , Estrutura Molecular , Pirróis/química , EstereoisomerismoRESUMO
Cyclopropane hemimalonates, when treated with sodium azide, undergo a tandem ring-opening decarboxylation to produce γ-azidobutyric acids in good yields. These adducts were hydrogenated to form γ-aminobutyric acid (GABA) methyl esters.
Assuntos
Ciclopropanos/química , Azida Sódica/química , Descarboxilação , Estrutura Molecular , Ácido gama-Aminobutírico/análogos & derivados , Ácido gama-Aminobutírico/síntese química , Ácido gama-Aminobutírico/químicaRESUMO
The reaction of cyclopropanes, geminally disubstituted with one carboalkoxy and one carbohydroxy group, undergoes ring-opening reactions with indole nucleophiles under catalyst-free, hyperbaric (13 kbar) conditions. An internal hydrogen bond is postulated as the mode of activation obviating the need for the Lewis acid catalyst normally used for such donor-acceptor cyclopropane chemistry. These conditions avoid decarboxylation and yield useful adducts with the carboxylic acid group intact for further elaboration.
Assuntos
Ciclopropanos/química , Malonatos/química , Ácidos/química , Ligação de Hidrogênio , Estrutura MolecularRESUMO
A Zn(NTf(2))(2) catalyzed tandem reaction consisting of a nucelophilic ring opening of 1,1-cyclopropanediesters by 2-alkynyl indoles followed by a Conia-ene ring closure results in the efficient one-step synthesis of tetrahydrocarbazoles. The adducts may be further elaborated to carbazoles.
RESUMO
Indoles, when treated with dimethyl diazomalonate under catalysis by Cu(acac)(2), undergo C-H insertion reactions regioselectively depending on the substitution pattern on the indole moiety. Indoles where the 3-position is substituted give high yields of the C2-H insertion product. Microwave conditions are also disclosed which show comparable yields with reduced reaction times.
Assuntos
Cobre/química , Indóis/química , Metano/análogos & derivados , Catálise , Metano/química , Estrutura MolecularRESUMO
The asymmetric total synthesis of (+)-isatisine A has been accomplished commencing with a Lewis acid-catalyzed cyclization of homochiral (S)-vinylcyclopropane diester and N-tosylindole-2-carboxaldehyde to construct the tetrahydrofuran ring. A palladium-catalyzed oxidative decarboxylation was utilized to obtain the dihydrofuran required for the subsequent dihydroxylation reaction to install the diol present on the tetrahydrofuran ring. The total synthesis was completed by an indole oxidation and electrophilic aromatic substitution sequence to construct isatisine A acetonide, which was then carried forward to the antipode of the natural product. The absolute configuration of the natural enantiomer (-)-isatisine A was determined to be C2(S), C9(R), C10(S), C12(R), and C13(R).