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Facile synthesis of heteroaryl substituted γ-lactams from nitrovinyl arenes

Aliphatic nitroalkanes with different functional groups were synthesized from the Michael addition reactions of active methylene compounds 2 and nitrovinyl arenes 1 in high yields. The synthesized Michael adducts were subjected to intramolecular cyclization to give heteroaryl substituted γ -lactams in good to high yields under mild reaction conditions. | Turkish Journal of Chemistry Turk J Chem 2018 42 29 35 http journals.tubitak.gov.tr chem ITAK c TUB Research Article doi 10.3906 kim-1705-25 Facile synthesis of heteroaryl substituted γ -lactams from nitrovinyl arenes Seda C INAR Canan UNALERO GLU Department of Chemistry Faculty of Science Hacettepe University Ankara Turkey Received 15.05.2017 Accepted Published Online 10.08.2017 Final Version 08.02.2018 Abstract Aliphatic nitroalkanes with different functional groups were synthesized from the Michael addition reactions of active methylene compounds 2 and nitrovinyl arenes 1 in high yields. The synthesized Michael adducts were subjected to intramolecular cyclization to give heteroaryl substituted γ -lactams in good to high yields under mild reaction conditions. Key words γ -Lactam aliphatic nitroalkanes Michael addition nitrovinyl arenes 1. Introduction Nitrogen-containing heterocycles attract chemists due to their utility in medicine. γ -Lactams among N - heterocycles constitute a synthetic challenge because of their important biological activities. 1 For this reason different methodologies have been developed for their synthesis. These methods include ring expansion of β - lactams 2 domino ring opening-cyclization of aziridines 3 intramolecular cyclization 4 5 3 3 cycloaddition 6 7 or radical cyclization reactions. 8 9 The Michael addition reaction of nucleophiles to electron-deficient species serves as a synthetic tool to form a carbon carbon bond within the synthesis of biologically active compounds. Okino et al. used γ - lactam formed from the cyclization of the Michael adduct of diethylmalonate and β -nitrostyrene in the total synthesis of R - - -baclofen. 10 Versatile functionality of the nitro group provides easy transformations into amine 11 12 ketone 13 14 oxime 15 16 or nitrile oxide 17 structures. In this manner nitro functionality-bearing Michael adducts are potential starting materials for the synthesis of biologically active molecules containing γ .