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By using platinum(lI) 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-alky-nylbenzylamides, 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. [ABSTRACT FROM AUTHOR]

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 alkynyl-amide and NBS-mediated oxidative Friedel-Crafts cyclization of the resulting 2-ketopiperazine were utilized as key reactions. [ABSTRACT FROM AUTHOR]

A new cleavage reaction of carbon–carbon triple bonds proceeds efficiently with NIS and TMSN3, giving the corresponding nitriles in moderate to good yields. [ABSTRACT FROM AUTHOR]

An efficient one-pot synthesis of 1,2,3-triazole-fused isoindoles from o -alkynylbenzaldehydes and trimethylsilyl azide (TMSN 3 ) is reported. The reaction proceeds through the formation of a diazide intermediate and a subsequent intramolecular azide-alkyne cycloaddition, providing a novel access to a variety of 8-azido-8 H -[1,2,3]triazolo[5,1- a ]isoindoles in high yields. [ABSTRACT FROM AUTHOR]

The syntheses of 2,3-dihydro-4-quinolones from 2-propargylphenylcarbamates by one-pot tandem process that involves Meyer-Schuster rearrangement or arylative Meyer-Schuster rearrangement/Michael addition of carbamate nitrogen to the resulting vinyl ketones have been developed. Phenylcarbamates tethering tertiary propargyl alcohols underwent arylative Meyer-Schuster rearrangement/Friedel-Crafts alkylation to produce 2,3-dihydroindenones. [ABSTRACT FROM AUTHOR]

An abstract of the article “Copper-Catalyzed Tandem Decyclization-Cyclization Reaction of N-Alkynyl-3-hydroxyisoindolin-1-ones Generated from N-Alkynyl Phthalimides:Selective Synthesis of ortho-(2-Oxazolyl) phenyl Ketones" by D. Homolka is presented.

Copper-catalysed arylative ring-closing reactions of 2-alkynylphenylcarbamates and 2-alkynylphenylureas with diaryliodonium salts gave C, N-double-arylated benzoxazin-2-ones and C-arylated benzoxazin-2-amines, respectively, both bearing fully substituted exocyclic olefins. On the other hand, the palladium-catalysed arylative ring-closing reaction of 2-alkynylphenylcarbamates gave C-arylated 2,3-disubstituted indoles. [ABSTRACT FROM AUTHOR]

Concise syntheses of 9-methoxyellipticine, 3,4-dihydroellipticine (µ-alkaloid D), 1,2,3,4-tetrahydroellipticine, 2-methyl-1,2,3,4-tetrahydroellipticine, olivacine, 3,4-dihydroolivacine, (±)-guatambuine, and (±)-janetine were developed starting from hexatriene intermediates readily obtained by Pd-catalyzed tandem cyclization/cross-coupling reaction of indolylborates. The route enables the facile construction of pyrido[4,3- b]carbazoles by Cu-catalyzed 6π-electrocyclization and subsequent transformation of the pyridocarbazole intermediates into pyrido[4,3- b]carbazole alkaloids. [ABSTRACT FROM AUTHOR]

A new approach to form iminoisocoumarins from readily available and stable 2-alkynylbenzamides was developed by using a tandem copper-catalyzed N-arylation and regioselective 6- endo- dig cyclization in the presence of diaryliodonium salts, a copper catalyst, and 2,6-di- tert-butylpyridine. The arylation occurred at the nitrogen atom rather than the oxygen atom of the amide group, the alkynyl carbon, or the benzene ring of the benzamide. Cyclization occurred through a preferential nucleophilic attack by the oxygen rather than the nitrogen atom of the amide group to produce iminoisocoumarin derivatives in good to moderate yields. [ABSTRACT FROM AUTHOR]

The synthesis of a wide variety of bisindolylmethanes is achieved via reaction of nitromethanes with vinylmagnesium bromide, followed by quenching with HCl or reaction with aldehydes. [ABSTRACT FROM AUTHOR]

The novel catalyst-free carbon-carbon triple bond cleavage reaction probably proceeds via an iodo vinyl azide as intermediate, derived from regioselective iodoazidation of the alkyne with NIS and trimethylsilyl azide. [ABSTRACT FROM AUTHOR]

The palladium-catalyzed tandem cyclization/cross-coupling reaction of triethyl(indol-2-yl)borate with vinyl bromide was successfully used in the concise total synthesis of the indolophenanthridine alkaloids, calothrixins A and B. [ABSTRACT FROM AUTHOR]

Abstract: The Pd(0)-catalyzed intramolecular cyanoamidation of several unsaturated cyanoformamides with alkenyl, allenyl, and alkynyl groups was investigated. In the cases of alkynyl and 1,1-disubstituted alkenyl cyanoformamides, the Pd(0)-catalyzed C–CN activation and subsequent insertion reaction proceeded smoothly and gave the corresponding lactams bearing a cyano group at the β-position in good yields. The mechanism of the reaction was also discussed. [Copyright &y& Elsevier]

Abstract: Investigation of the palladium-catalyzed tandem cyclization-cross-coupling reaction using indolylborate (2) as a transfer agent has been carried out. Furthermore, the cross-coupling reaction performed under carbon monoxide led to the generation of indolyl ketones. [Copyright &y& Elsevier]

Abstract: Direct, efficient syntheses of the benzimidazo[2,1-a]isoquinoline ring system have been achieved with 2-bromoarylaldehydes, terminal alkynes, and 1,2-phenylenediamines by a microwave-accelerated tandem process in which a Sonogashira coupling, 5-endo cyclization, oxidative aromatization, and 6-endo cyclization can be performed in a single synthetic operation. [Copyright &y& Elsevier]

Cu-catalyzed 6π-electrocyclization of triene-substrates of type (I) provides a facile access to pyrido[4,3-b]carbazoles, which represent advanced intermediates for the construction of various ellipticine and olivacine alkaloids. [ABSTRACT FROM AUTHOR]

affording a series of iminoisocoumarins [ABSTRACT FROM AUTHOR]

and the subsequent Huisgen cyclization to bis-triazoles [ABSTRACT FROM AUTHOR]

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 BF 3 ·Et 2 O-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.

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.

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 β,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.

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.

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.

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., (© 2012 American Chemical Society)

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.

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.

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.

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.

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.