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Research describes an highly diastereoselective intermolecular coupling of imines possessing a beta-hydroxy group with a Lewis acid and a single-electron reduction system. The reaction represents imine dimerization with samarium involving chelation control by aluminum for the N-benzylideneamino alcohol radical.

Research has been conducted on the optically active imino alcohol-type aldimine. The Barbier-type allylation of this aldimine which proceeded with high regio- and stereoselectivity is described.

Platinum(II) chloride as a Lewis acid catalyst was employed to perform concise and efficient syntheses of indole carbamates, 1,2-dihydroisoquinoline carbamates, macrocyclic indole carbamates, indole ureas and indole phosphoranes. The reaction rate could be enhanced by performing the reaction under microwave irradiation.

The development of a concise synthesis of the CDE ring system of the tetrahydroisoquinoline antitumor alkaloids such as saframycins, renieramycins, and ecteinascidins is reported. The key steps in the reaction include Au(I)-catalyzed intramolecular hydroamidation and NBS-mediated oxidative Friedel-Crafts cyclization.

The development of a new atom-economical In[(OTf).sub.3]-catalyzed synthesis of ring-condensed heteroaromatic compounds via a domino intramolecular nucleophilic attack/intermolecular cycloaddition/dehydration reaction is reported. The synthesis used readily available ortho-alkynylanilines and ortho-alkynylbenzaldehydes as starting materials.

A study develops 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 domino reactions. The method provides a versatile tool for further synthesis of natural products and random screening in the search for drug candidates.

Regioselective addition of 1,3‐dicarbonyl compounds to N‐alkynyl‐3‐hydroxyisoindolin‐1‐ones (α‐hydroxy ynamides) was accomplished with the use of NiII salt catalysts. The reaction proceeded by a tandem decyclization–addition–cyclization mechanism, in which a ketenimine intermediate is formed via NiII‐catalyzed isomerization of α‐hydroxy ynamides. The BF3‐catalyzed intramolecular dehydrative condensation of the resulting α‐hydroxy enamides afforded tricyclic isoindolones in good yields. α‐Regioselective addition of 1,3‐dicarbonyl compounds to N‐alkynyl‐3‐hydroxyisoindolin‐1‐ones (α‐hydroxy ynamides) was accomplished with the use of NiII salt catalysts. This addition proceeded via a keteneimine intermediate, and the adducts were converted into tricyclic isoindolones. [ABSTRACT FROM AUTHOR]

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 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]

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. Electron-donating groups accelerated this tandem haloallenyl ketone formation--furan formation reaction sequence on the aromatic rings. [ABSTRACT FROM AUTHOR]

Novel indium-mediated radical cyclization reactions of aliphatic iodoalkynes have been studied. Treatment of iodoalkynes with a catalytic amount of In (0.1 equiv) and I2 (0.05 equiv) promotes atom-transfer 5-exo cyclization to give five-membered alkenyl iodides. In contrast, reaction with In (2 equiv) and I2 (1 equiv) yields reductive 5-exo cyclization products via the same 5-exo cyclization. Both processes are most likely initiated by low-valent indium species. To demonstrate versatility of these reactions, optically active HIV protease inhibitors were synthesized by this reductive cyclization method. Among them, several products, which contain a hydroxyethylamine dipeptide isostere as a transition state-mimicking substructure, proved to possess potent activity (IC50 = 5-39 nM) against a wide spectrum of HIV strains, including multidrug-resistant variants. [ABSTRACT FROM AUTHOR]

Upon treatment with In and I2, mono-substituted alkenes having an iodine substituent at the δ-position of the tether gave the corresponding iodinated cyclic compounds, whereas di- and tri-substituted alkenes gave the corresponding hydroxylated cyclic compounds. Alkenes bearing leaving groups at the allylic position were transformed only to the corresponding vinyl substituted cyclic compounds. On the other hand, alkynes bearing good leaving groups at the propargylic position gave allenic products selectively. [Copyright &y& Elsevier]

Novel indium-mediated reactions have been studied. Treatment of iodoalkyne with In (0.5 equiv.) and I2 (0.5 equiv.) in MeOH promotes the atom-transfer 5-exo-cyclization. In contrast, the reaction with In (2 equiv.) and I2 (1 equiv.) gives rise to a reductive 5-exo-cyclized product. [Copyright &y& Elsevier]

We have demonstrated the usefulness of recoverable and reusable immobilized OsO4 in [emim]BF4 for dihydroxylation of several olefins. This approach is simple and practical. It should be noted that the volatility and toxicity of OsO4 are greatly suppressed when the ionic liquid [emim]BF4 is used. [Copyright &y& Elsevier]