Facile syntheses of 3,4-disubstituted pyrroline nitroxides and their further synthetic applications

Úr, Györgyi and Kálai, Tamás and Hideg, Kálmán (2016) Facile syntheses of 3,4-disubstituted pyrroline nitroxides and their further synthetic applications. TETRAHEDRON LETTERS, 57 (7). pp. 778-780. ISSN 0040-4039

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Abstract

Lithiation of an alfa,beta-unsaturated pyrroline nitroxide ester with LTMP at the beta-carbon followed by treatment with electrophiles led to a new series of 3,4-disubstituted pyrroline nitroxides, which could be used as valuable paramagnetic building blocks. The new compounds were tested in Sonogashira and Stille cross coupling reactions, which offered methyl 1-oxyl-4-substituted-2,2,5,5-tetramethyl-2,5-dihydro-1H-pyrrol-3-carboxylate radicals for new C-C bond formation in poor to moderate yields. The reaction of an alfa,beta-unsaturated pyrroline nitroxide ester with methyl chloroformate generated diester 2b; the partial hydrolysis product of this reaction was shown to be a key compound for the synthesis of paramagnetic uracil derivative 10.

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