RESUMO
We report an efficient synthetic route to 9-arylfluorenes and biaryl compounds from 1,6-diynes and aldehydes via inter- and intramolecular alkyne-carbonyl metathesis/1,6-addition/oxidative aromatization reactions. These tandem reactions are initiated by a BF3·Et2O-promoted tandem inter- and intramolecular alkyne-carbonyl metathesis of 1,6-diynes with carbonyl compounds followed by an In(OTf)3-catalyzed 1,6-addition/oxidative aromatization with iodobenzene diacetate.
RESUMO
Deacetylation of enynyl acetates under basic conditions allows convenient access to reactive allenyl ketones, which can then undergo 1,4-addition of nucleophiles to furnish ß,γ-unsaturated ketones. Benzofuran and indole derivatives have also been obtained from enynyl acetates with an o-hetero-atom-substituted aryl group via intramolecular 1,4-addition.
Assuntos
Acetatos/química , Cetonas/síntese química , Acetilação , Cetonas/química , Estrutura MolecularRESUMO
Selective carbophilic monoaddition on N-alkynyl phthalimides was performed with organometallic reagents to afford 3-substituted N-alkynyl-3-hydroxyisoindolin-1-ones (α-hydroxy ynamides) as a new subgroup of ynamides. Owing to the alkynyl motif on the nitrogen atom, α-hydroxy ynamides were easily isomerized to the corresponding ortho-(2-oxazolyl)phenyl ketones in a CuCl-catalyzed tandem decyclization-cyclization reaction under mild conditions.
RESUMO
Aryl alkyl alkynes reacted with N-iodosuccinimide (NIS) and trimethylsilyl azide (TMSN3), leading to α,α-diazidoketones via the regioselective addition of IN3 to alkynes. Huisgen cyclization of α,α-diazidoketones generated bis-triazole compounds.
Assuntos
Alcinos/química , Azidas/química , Cetonas/química , Cetonas/síntese química , Silanos/química , Succinimidas/química , Triazóis/química , Catálise , Ciclização , Estrutura MolecularRESUMO
Bi(OTf)3-catalyzed Meyer-Schuster rearrangement of electron-rich propargyl alcohols, followed by 1,4-addition of the resulting vinyl ketone, proceeded smoothly though Meyer-Schuster rearrangement of primary propargyl alcohols is rare. This tandem reaction can be extended to an intramolecular version, featuring a one-pot dihydroquinolone synthesis.
Assuntos
Alcinos/química , Hidroquinonas/síntese química , Cetonas/química , Mesilatos/química , Propanóis/química , Compostos de Vinila/química , Catálise , Hidroquinonas/química , Estrutura MolecularRESUMO
A one-pot approach to 3,3'-bisindolylmethane derivatives from nitrobenzene derivatives through the Bartoli indole synthesis was developed, in which the acid used to quench the reaction markedly affected its outcome. Quenching the reaction with concd HCl produced 3,3'-bisindolylmethane in contrast to the formation of 7-substituted indole by quenching with NH4Cl.
Assuntos
Indóis/síntese química , Catálise , Ciclização , Indóis/química , Estrutura MolecularRESUMO
A new cleavage reaction of carbon-carbon triple bonds proceeds efficiently with NIS and TMSN3, giving the corresponding nitriles in moderate to good yields.
Assuntos
Alcinos/química , Carbono/química , Ouro/química , Nitrilas/química , Nitrilas/síntese química , CatáliseRESUMO
Multisubstituted furans were readily prepared from (Z)- or (E)-conjugated enynyl acetates with NXS under metal-free conditions at room temperature via the same haloallenyl ketone intermediates. This tandem haloallenyl ketone formation-furan formation reaction sequence was accelerated by electron-donating groups on the aromatic rings.
Assuntos
Acetatos/química , Alcadienos/química , Furanos/química , Cetonas/química , Elétrons , Estrutura Molecular , EstereoisomerismoRESUMO
Regio- and stereoselective cohalogenation of alkynes with NXS (X = Br, I) was achieved, and the stereoselectivity of the resulting alkenes was dependent on the substituent on the alkyne. Cohalogenation and successive cross-coupling gave multisubstituted enol esters in a one-pot process.
Assuntos
Alcenos/química , Alcinos/química , Hidrocarbonetos Halogenados/química , Álcoois , Ésteres , Estrutura Molecular , EstereoisomerismoRESUMO
Concise and efficient syntheses of various trans-2,3-disubstituted-2,3-dihydro-4-quinolones have been achieved via tandem Hofmann-type rearrangement of 2-alkynylbenzamides, nucleophilic addition of alcohols to the isocyanate intermediates, intermolecular [2+2]-cycloaddition with carbon-carbon triple bonds and aldehydes, and intramolecular aminocyclization of nitrogen of carbamates to the α,ß-unsaturated ketones.
Assuntos
4-Quinolonas/química , 4-Quinolonas/síntese química , Carbamatos/química , Alcenos/química , Catálise , Ciclização , Cetonas/química , Estrutura Molecular , EstereoisomerismoRESUMO
The concise total synthesis of calothrixins A and B has been accomplished by utilizing the one-pot formation of hexatriene as a key intermediate via the palladium-catalyzed tandem cyclization/cross-coupling reaction of triethyl(indol-2-yl)borate. In another key transformation, the indolo[3,2-j]phenanthridine core was prepared in high yield via Cu(I)-mediated 6π-electrocyclization.
Assuntos
Alcaloides Indólicos/síntese química , Catálise , Cobre/química , Ciclização , Estrutura Molecular , Paládio/químicaRESUMO
By using platinum(II) chloride as a Lewis acid catalyst, concise and efficient syntheses of indole carbamates, 1,2-dihydroisoquinoline carbamates, macrocyclic indole carbamates, indole ureas, and indole phosphoranes have been achieved via tandem Hofmann-type rearrangement of 2-alkynylbenzamides and 2-alkynylbenzylamides, nucleophilic addition of alcohols and amines to the isocyanate intermediates, and intramolecular aminocyclization of the thus-formed carbamates and ureas to 2-alkynyl functions. A variety of nucleophiles such as alcohols, amines, and stable Wittig reagents could be introduced to the highly electrophilic carbon of the isocyanate intermediates derived from amides. We observed enhancement of the reaction rates when the reactions were run under microwave irradiation.
Assuntos
Amidas/química , Carbamatos/síntese química , Indóis/síntese química , Isoquinolinas/síntese química , Ácidos de Lewis/química , Platina/química , Carbamatos/química , Catálise , Ciclização , Indicadores e Reagentes/química , Indóis/química , Isoquinolinas/química , Micro-Ondas , Estrutura MolecularRESUMO
A concise synthesis of the CDE ring system of the tetrahydroisoquinoline antitumor alkaloids such as saframycins, renieramycins, and ecteinascidins has been developed. Both Au(I)-catalyzed intramolecular hydroamidation of alkynylamide and NBS-mediated oxidative Friedel-Crafts cyclization of the resulting 2-ketopiperazine were utilized as key reactions.
Assuntos
Alcaloides/síntese química , Tetra-Hidroisoquinolinas/síntese química , Antineoplásicos/síntese química , Ciclização , Estrutura Molecular , OxirreduçãoRESUMO
Starting from ortho-alkynylbenzaldehydes and ortho-alkynylanilines, In(OTf)3-catalyzed synthesis of ring-condensed heteroaromatic compounds was developed via a domino intramolecular nucleophilic attack/intermolecular cycloaddition/dehydration reaction.
Assuntos
Benzaldeídos/química , Compostos Heterocíclicos/química , Índio/química , Ácidos Sulfanílicos/química , Catálise , Estrutura MolecularRESUMO
By using carbophilic Lewis acids, In(OTf)3, NiCl2, and AuCl(PPh3)/AgNTf2, a concise and efficient synthesis of 1,3-disubstituted 1,2-dihydroisoquinolines has been achieved via tandem nucleophilic addition and cyclization of 2-(1-alkynyl)arylaldimines. Addition of proton sources such as water, CF3CH2OH, and 2,6-di-tert-butyl-4-methoxyphenol was essential for the Lewis acid-catalyzed tandem reactions with organometallic reagents. By switching these catalysts, various types of nucleophiles such as allylstannanes, silyl enol ethers, alkenylboronic acids, and active methylene compounds could be introduced at the C1 position of 1,2-dihydroisoquinolines in this transformation. Furthermore, this method proved to be applicable to the synthesis of 1H-isochromene derivatives via the same tandem reaction of 2-(1-alkynyl)arylaldehydes.
Assuntos
Aldeídos/química , Alcinos/química , Benzopiranos/síntese química , Iminas/química , Isoquinolinas/síntese química , Alcinos/síntese química , Catálise , CiclizaçãoRESUMO
[reaction: see text] The five- to seven-membered alpha-alkylidene lactams were prepared in 45-99% yield by the palladium-catalyzed cyanoamidation of alkynyl cyanoformamides. The reaction proceeded exclusively in a 5-exo mode, giving the corresponding (Z)-alkenes as major products. The reaction was also applied to 1,1-disubstituted alkenes to afford oxindoles bearing a quaternary carbon center.
Assuntos
Alcenos/química , Alcinos/química , Lactamas/síntese química , Nitrilas/química , Paládio/química , Amidas/química , Catálise , Técnicas de Química Combinatória , Estrutura Molecular , EstereoisomerismoAssuntos
Índio/química , Isoquinolinas/síntese química , Mesilatos/química , Alcinos/química , Catálise , Ciclização , Iminas/químicaRESUMO
We have developed efficient catalytic methods for the stereoselective and diversity synthesis of various (E)-, (Z)-, and disubstituted 3-alkylideneoxindoles and 3-alkylidenebenzofuran-2-ones via palladium-catalyzed Heck/Suzuki-Miyaura, Heck/Heck, and Heck/carbonylation/Suzuki-Miyaura domino reactions.
Assuntos
Indóis/síntese química , Paládio/química , Catálise , Espectroscopia de Ressonância Magnética , Oxindóis , Espectrometria de Massas de Bombardeamento Rápido de Átomos , Espectrofotometria Infravermelho , EstereoisomerismoRESUMO
Efficient methods for stereoselective synthesis of various (E)-, (Z)-, and disubstituted 3-alkylideneoxindoles were investigated using tandem In-mediated carbometalation and ligandless Pd-catalyzed coupling reaction.