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    Design of pyrazolo-pyrrolo-pyrazines and pyrazolo-pyrrolo-diazepines via AuCl3-catalyzed and NaH-supported cyclization of N -propargyl pyrazoles
    (American Chemical Society, 2015) Başçeken, Sinan; Balcı, Mehmet
    A concise synthetic methodology for new heterocyclic scaffolds, such as pyrazolo-pyrrolo-pyrazine and pyrazolo-pyrrolo-diazepine skeletons, was developed. The key features of this method include (i) synthesis of pyrrole-derived ?,?-alkynyl ketones, (ii) introduction of various substituents into the alkyne functionality by Sonogashira cross-coupling, (iii) synthesis of pyrazole units by the reaction of ?,?-alkynyl compounds with hydrazine monohydrate, (iv) gold-catalyzed cyclization of pyrazoles with alkyne units, and (v) cyclization with NaH. Furthermore, this methodology allows various substituents to be introduced into all positions of the target compounds. © 2015 American Chemical Society.
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    Intramolecular Gold-Catalyzed and NaH-Supported Cyclization Reactions of N-Propargyl Indole Derivatives with Pyrazole and Pyrrole Rings: Synthesis of Pyrazolodiazepinoindole, Pyrazolopyrazinoindole, and Pyrrolopyrazinoindole
    (American Chemical Society, 2015) Başçeken, Sinan; Kaya, Serdal; Balcı, Metin
    Gold-catalyzed and NaH-supported intramolecular cyclization of N-propargyl indole derivatives with pyrazole and pyrrole units attached to indole is described. An efficient route to the synthesis of pyrazolodiazepinoindole, pyrazolopyrazinoindole, and pyrrolopyrazinoindole has been established. First, N-propargyl 2-(1H-pyrazol-5-yl)-1H-indole and 2-(1H-pyrrol-2-yl)-1H-indole were synthesized. Introduction of various substituents into the alkyne functionality was accomplished by Sonogashira cross-coupling reaction. Gold-catalyzed cyclization of pyrazoles having a terminal alkyne afforded the 6-exo-dig cyclization product. However, exclusive formation of 7-endo-dig cyclization products was observed with internal alkynes. On the other hand, cyclization with NaH only resulted in the formation of 6-exo-dig cyclization products regardless of the substitution of the alkyne functionality. Allenic intermediates were postulated for this outcome. © 2015 American Chemical Society.
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    Nucleophilic and electrophilic cyclization of N-alkyne-substituted pyrrole derivatives: Synthesis of pyrrolopyrazinone, pyrrolotriazinone, and pyrrolooxazinone moieties
    (Beilstein-Institut Zur Forderung der Chemischen Wissenschaften, 2017) Yenice, Işıl; Başçeken, Sinan; Balcı, Metin
    Intramolecular nucleophilic and electrophilic cyclization of N-alkyne-substituted pyrrole esters is described. Efficient routes towards the synthesis of pyrrolopyrazinone, pyrrolotriazinone and pyrrolooxazinone have been developed. First, N-alkyne-substituted pyrrole ester derivatives were synthesized. Introduction of various substituents into the alkyne functionality was accomplished by a copper-catalyzed cross-coupling reaction. Nucleophilic cyclization of N-alkyne-substituted methyl 1H-pyrrole-2-carboxylates with hydrazine afforded the 6-exo-dig/6-endo-dig cyclization products depending on the electronic nature of the substituents attached to the alkyne. On the other hand, cyclization of N-alkyne-substituted methyl 1H-pyrrole-2-carboxylates with iodine only resulted in the formation of the 6-endo-dig cyclization product regardless of the substitution of the alkyne functionality. © 2017 Yenice et al.
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    Study of asymmetric aldol and Mannich reactions catalyzed by proline-thiourea host-guest complexes in nonpolar solvents
    (2013) Demir, Ayhan Sıtkı; Başçeken, Sinan
    A proline-thiourea host-guest complex has been described as a good catalyst for asymmetric reactions such as aldol and Mannich reactions. High stereoselectivities were obtained under optimal conditions. Thiourea was observed to have an important effect on the reactivity and selectivity, even in an unconventional nonpolar reaction medium and without the need to utilize low temperatures. This proline-thiourea host-guest system has the ability to participate in a hydrogen bonding network.© 2013 Elsevier Ltd. All rights reserved.
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    Synthesis of a bipyridine-derived achiral thiourea trifluoromethanesulfonic acid salt and its application as an additive in organocatalytic asymmetric reactions
    (2013) Demir, Ayhan Sıtkı; Başçeken, Sinan
    The host-guest complex of a proline-thiourea bipyridine trifluoromethanesulfonic acid salt can catalyze organocatalytic asymmetric reactions such as aldol, Michael, and Mannich in polar protic medium with high stereoselectivities. The privileged bipyridine backbone and the thiourea motif are essential to the activity and enantioselectivity through hydrogen bonding interactions. © 2013 Elsevier Ltd. All rights reserved.
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    Synthesis of pyrrolo-pyrrolo-pyrazines via the Pd/C-catalyzed cyclization of N-propargyl pyrrolinyl-pyrrole derivatives
    (Elsevier Ltd, 2019) Aslanoğlu, Furgan; Başçeken, Sinan; Balcı, Metin
    A novel and efficient synthesis of N-substituted dipyrrolo[1,2-a:2',1'-c]pyrazine derivatives has been developed. The synthetic strategy relies on the synthesisof 4',5'-dihydro-1H,3'H-2,2'-bipyrrole, followed by the reaction with propargyl bromide. Various substituents were introduced to the alkyne functionality using the Sonogashira coupling reaction. Aromatization of the dihydropyrrole ring followed by an intramolecular cyclization reaction between the alkyne functionality and the pyrrole nitrogen atom was catalyzed by Pd/C at high temperature to furnish the desired dipyrrolo-pyrazine skeleton. (C) 2019 Elsevier Ltd.