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ABSTRACT: A new cleavage reaction of carbon-carbon triple bonds proceeds efficiently with NIS and TMSN3, giving the corresponding nitriles in moderate to good yields.
Organic Letters 05/2013; · 5.86 Impact Factor
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ABSTRACT: 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.
The Journal of Organic Chemistry 03/2012; 77(8):3944-51. · 4.45 Impact Factor
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The Journal of Organic Chemistry 03/2012; 77(5):2578. · 4.45 Impact Factor
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ABSTRACT: 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 Journal of Organic Chemistry 09/2011; 76(21):9133-8. · 4.45 Impact Factor
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ABSTRACT: 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,β-unsaturated ketones.
The Journal of Organic Chemistry 09/2011; 76(21):9139-43. · 4.45 Impact Factor
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ABSTRACT: 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.
Organic Letters 07/2011; 13(13):3356-9. · 5.86 Impact Factor
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ABSTRACT: 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.
The Journal of Organic Chemistry 10/2010; · 4.45 Impact Factor
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Angewandte Chemie International Edition 11/2009; 48(51):9693-6. · 13.45 Impact Factor
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ABSTRACT: Palladium-catalyzed tandem cyclization–cross-coupling reaction of indolylborate 2 and vinyl bromide 5 was successfully applied in a short formal synthesis of olivacine. The reaction of 2 with 5 in the presence of Pd(OAc)2 readily afforded three kinds of products, triene derivative 6 and vinylindole derivative 7, along with a small amount of the piperidine derivative 8 (Scheme 2). On the other hand, the reactions of 2 with bromide 10 or 15 were also examined (Schemes 4 and 5), and their outcome markedly depended on the relative ease of ring closure as a function of ring size. Irradiation of 6 with a high-pressure mercury lamp (→9; Scheme 2), followed by removal of the N-[(benzyloxy)carbonyl] group and subsequent oxidation afforded, after deprotection, pyridocarbazole 23, and the conversion of 23 to olivacine is known (Scheme 6).
Helvetica Chimica Acta 10/2008; 91(10):1828 - 1837. · 1.48 Impact Factor
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ABSTRACT: 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.
The Journal of Organic Chemistry 08/2008; 73(13):5135-8. · 4.45 Impact Factor
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ABSTRACT: 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.
The Journal of Organic Chemistry 08/2008; 73(13):5206-9. · 4.45 Impact Factor
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ABSTRACT: 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.
The Journal of Organic Chemistry 07/2007; 72(12):4462-8. · 4.45 Impact Factor
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ABSTRACT: ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
ChemInform 02/2007; 38(12).
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ABSTRACT: [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.
Organic Letters 07/2006; 8(13):2711-3. · 5.86 Impact Factor
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Angewandte Chemie International Edition 07/2006; 45(23):3822-5. · 13.45 Impact Factor
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ABSTRACT: 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.
The Journal of Organic Chemistry 09/2005; 70(17):6972-5. · 4.45 Impact Factor
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ABSTRACT: 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.
Organic Letters 09/2004; 6(16):2825-8. · 5.86 Impact Factor
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ABSTRACT: 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 I(2) (0.05 equiv) promotes atom-transfer 5-exo cyclization to give five-membered alkenyl iodides. In contrast, reaction with In (2 equiv) and I(2) (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 (IC(50) = 5-39 nM) against a wide spectrum of HIV strains, including multidrug-resistant variants.
The Journal of Organic Chemistry 05/2004; 69(7):2417-22. · 4.45 Impact Factor
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ABSTRACT: The intermolecular pinacol-type coupling reaction and allylation reaction of optically active imines bearing a β-hydroxy group were performed stereoselectively with metallic samarium after treatment of the imines with trimethylaluminum.
01/2001;
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ABSTRACT: Photoinduced epimerization of chiral Fe aminocarbene complexes [(h5-C5H5)Fe(CO)(L){:C(NHR2)(CH2R1)}]+ BF4- [L = PPh3, P( p-tolyl)3; R1 = H, Me; R2 = CH2Ph, CH(Me)Ph] was obsd. in 10% water-MeOH, MeOH, EtOH, THF and CH2Cl2 at room temp. Isotope exchange expts. have unambiguously established that reversible phosphine ligand (L) dissocn. rather than reversible loss of the CO ligand is the only mechanism operating. [on SciFinder (R)]
Journal of the Chemical Society, Perkin Transactions 2. 01/1998;
