on the occasion of his 70th birthday.Abstract: A series of tetrahydropyrazolo[1,5-c]pyrimidine-2,7(1H,3H)-diones 3a-h as the first representatives of the so far unexplored saturated heterocyclic system have been synthesized, formally in 12 steps from methyl acrylate (4). The synthesis comprises a four-step preparation of methyl N-Cbz-5-alkylamino-3-oxopentanoates 9a-c, their three-step transformation into 5-{2-[(alkyl)(benzyloxycarbonyl)amino]ethyl}pyrazolidin-3-ones 12a-c, three-step selective alkylation of the amidic N-2 to give 2-alkyl-5-{2-[(alkyl)(benzyloxycarbonyl)amino]ethyl}pyrazolidin-3-ones 16b-h, followed by hydrogenolytic Cbz-deprotection and subsequent cyclization of the intermediate 1,4-diamine with CDI to furnish the title compounds 3. Most of the synthetic steps were performed as a one-pot transformation.
Synthesis of Tetrahydropyrazolo[1,5-c]pyrimidine-2,7(1H,3H)-diones. -A straightforward synthesis of the title compounds (VII) and (XII) is presented. The strategy involves preparation of selectively functionalized pyrrazolidinones and final cyclization with CDI. -(GROSELJ*, U.; PODLOGAR, A.; NOVAK, A.; DAHMANN, G.; GOLOBIC, A.; STANOVNIK, B.; SVETE, J.; Synthesis 45 (2013) 5, 639-650, http://dx.doi.org/10.1055/s-0032-1318107 ; Fac. Chem. Chem. Technol.,
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