ABSTRACT
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.
ABSTRACT
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.
Subject(s)
Acetates/chemistry , Ketones/chemical synthesis , Acetylation , Ketones/chemistry , Molecular StructureABSTRACT
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.
ABSTRACT
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.
Subject(s)
Alkynes/chemistry , Azides/chemistry , Ketones/chemistry , Ketones/chemical synthesis , Silanes/chemistry , Succinimides/chemistry , Triazoles/chemistry , Catalysis , Cyclization , Molecular StructureABSTRACT
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.
Subject(s)
Alkynes/chemistry , Hydroquinones/chemical synthesis , Ketones/chemistry , Mesylates/chemistry , Propanols/chemistry , Vinyl Compounds/chemistry , Catalysis , Hydroquinones/chemistry , Molecular StructureABSTRACT
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.
Subject(s)
Indoles/chemical synthesis , Catalysis , Cyclization , Indoles/chemistry , Molecular StructureABSTRACT
A new cleavage reaction of carbon-carbon triple bonds proceeds efficiently with NIS and TMSN3, giving the corresponding nitriles in moderate to good yields.
Subject(s)
Alkynes/chemistry , Carbon/chemistry , Gold/chemistry , Nitriles/chemistry , Nitriles/chemical synthesis , CatalysisABSTRACT
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.
Subject(s)
Acetates/chemistry , Alkadienes/chemistry , Furans/chemistry , Ketones/chemistry , Electrons , Molecular Structure , StereoisomerismABSTRACT
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.
Subject(s)
Alkenes/chemistry , Alkynes/chemistry , Hydrocarbons, Halogenated/chemistry , Alcohols , Esters , Molecular Structure , StereoisomerismABSTRACT
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.
Subject(s)
4-Quinolones/chemistry , 4-Quinolones/chemical synthesis , Carbamates/chemistry , Alkenes/chemistry , Catalysis , Cyclization , Ketones/chemistry , Molecular Structure , StereoisomerismABSTRACT
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.
Subject(s)
Indole Alkaloids/chemical synthesis , Catalysis , Copper/chemistry , Cyclization , Molecular Structure , Palladium/chemistryABSTRACT
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.
Subject(s)
Amides/chemistry , Carbamates/chemical synthesis , Indoles/chemical synthesis , Isoquinolines/chemical synthesis , Lewis Acids/chemistry , Platinum/chemistry , Carbamates/chemistry , Catalysis , Cyclization , Indicators and Reagents/chemistry , Indoles/chemistry , Isoquinolines/chemistry , Microwaves , Molecular StructureABSTRACT
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.
Subject(s)
Alkaloids/chemical synthesis , Tetrahydroisoquinolines/chemical synthesis , Antineoplastic Agents/chemical synthesis , Cyclization , Molecular Structure , Oxidation-ReductionABSTRACT
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.
Subject(s)
Benzaldehydes/chemistry , Heterocyclic Compounds/chemistry , Indium/chemistry , Sulfanilic Acids/chemistry , Catalysis , Molecular StructureABSTRACT
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.
Subject(s)
Aldehydes/chemistry , Alkynes/chemistry , Benzopyrans/chemical synthesis , Imines/chemistry , Isoquinolines/chemical synthesis , Alkynes/chemical synthesis , Catalysis , CyclizationABSTRACT
[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.
Subject(s)
Alkenes/chemistry , Alkynes/chemistry , Lactams/chemical synthesis , Nitriles/chemistry , Palladium/chemistry , Amides/chemistry , Catalysis , Combinatorial Chemistry Techniques , Molecular Structure , StereoisomerismABSTRACT
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.
Subject(s)
Indoles/chemical synthesis , Palladium/chemistry , Catalysis , Magnetic Resonance Spectroscopy , Oxindoles , Spectrometry, Mass, Fast Atom Bombardment , Spectrophotometry, Infrared , StereoisomerismABSTRACT
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.