- Synthesis of cyclopentaquinolinone and cyclopentapyridinone from: Ortho-alkynyl-N-arylaldehyde via superbase-promoted C-N, C-O and C-C bond formation
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An environmentally benign, transition metal-free, superbase-mediated intramolecular annulation of o-alkynylaldehydes with primary amines forms highly functionalized amino-substituted cyclopentaquinolinones and cyclopentapyridinones via C-N, C-C, and CO bond formation. Contrary to the traditional approaches of ring closures, a different mode of annulation is disclosed. The protocol involves the in situ generations of imine intermediate followed by potassium hydroxide-promoted intramolecular cyclization and subsequent dimethyl sulfoxide induced dehydrogenation leads to the formation of N-heterocycles. X-ray crystallographic studies support the assigned structures of the amino-fused N-heterocycles.
- Saini, Kapil Mohan,Saunthwal, Rakesh K.,Sushmita,Verma, Akhilesh K.
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supporting information
p. 5594 - 5601
(2020/08/21)
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- On water: Silver-catalyzed domino approach for the synthesis of benzoxazine/oxazine-fused isoquinolines and naphthyridines from o-alkynyl aldehydes
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An operationally simple domino approach for the silver-catalyzed synthesis of oxazine/benzoxazine-fused isoquinolines 5a-q and naphthyridines 6a-v by the reaction of o-alkynyl aldehydes 3a-aa with amines having embedded nucleophiles 4a-d under mild reacti
- Verma, Akhilesh K.,Choudhary, Deepak,Saunthwal, Rakesh K.,Rustagi, Vineeta,Patel, Monika,Tiwari, Rakesh K.
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p. 6657 - 6669
(2013/07/26)
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- AgI-catalyzed cascade strategy: Regioselective access to diversely substituted fused benzimidazo[2,1-a]isoquinolines, naphthyridines, thienopyridines, and quinoxalines in water
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An environmentally benign and operationally simple one-pot approach to the regioselective tandem synthesis of diversely substituted fused benzimidazo[2,1-a]isoquinolines, naphthyridines, thienopyridines, and quinoxalines from o-alkynylaldehydes and arylamines with tethered nucleophiles using AgI as catalyst in water is described. The reaction showed selective N-C bond formation on the more electrophilic alkynyl carbon, resulting in the regioselective 6-endo-dig cyclized products in good to excellent yields. The proposed mechanistic pathway for the synthesis of fused heterocycles proceeding through formation of ring A prior to ring B, which formed through a second intramolecular attack of the nitrogen onto the alkynyl carbon, was supported by mechanistic experiments and X-ray crystallographic studies of isolated intermediate U and cyclized product 5a. Comparative experiments showed the viability of intramolecular nucleophilic attack over intermolecular attack of an external nucleophile. This catalytic, green protocol has been efficiently applied for the bis-tandem cyclization in water. An eco-friendly, one-pot cascade approach to benzimidazoles and quinoxalines in water using AgNO 3 as catalyst from o-alkynyl aldehydes and amines with tethered nucleophiles, has been developed. Selective 6-endo-dig regioselectivity and structural diversity are accomplished in good yields with a range of substrates. X-ray crystallographic studies and mechanistic experiments are also presented. Copyright
- Rustagi, Vineeta,Tiwari, Rakesh,Verma, Akhilesh Kumar
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supporting information
p. 4590 - 4602
(2012/11/07)
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- Synthesis of substituted isoquinolines by electrophilic cyclization of iminoalkynes
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The tert-butylimines of o-(1-alkynyl)benzaldehydes and analogous pyridinecarbaldehydes have been cyclized under very mild reaction conditions in the presence of I2, ICl, PhSeCl, PhSCl, and p-O2-NC6H4SCl to give the corresponding halogen-, selenium-, and sulfur-containing disubstituted isoquinolines and naphthyridines, respectively. This methodology accommodates a variety of iminoalkynes and affords the anticipated heterocycles in moderate to excellent yields. Monosubstituted isoquinolines and naphthyridines have been synthesized by the metal-catalyzed ring closure of these same iminoalkynes. The silver-catalyzed ring closure is highly effective in cyclizing aryl-, alkenyl-, and alkyl-substituted iminoalkynes at 50°C.
- Huang, Qinhua,Hunter, Jack A.,Larock, Richard C.
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p. 3437 - 3444
(2007/10/03)
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- General synthetic method for naphthyridines and their N-oxides containing isoquinolinic nitrogen
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Substituted naphthyridines containing isoquinolinic nitrogen were synthesized by the reaction of o-ethynylpyridinecarbaldehydes with ammonia. The synthesis of their N-oxides was also achieved by a basic cyclization reaction of the same pyridine derivatives via the corresponding oximes.
- Numata, Atsushi,Kondo, Yoshinori,Sakamoto, Takao
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p. 306 - 311
(2007/10/03)
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