title: Combining Biginelli multicomponent and click chemistry: generation of 6-(1,2,3-triazol-1-yl)-dihydropyrimidone libraries.
abstract: Efficient solution-phase protocols for the high-throughput synthesis of 6-(1,2,3-triazol-1-yl)-dihydropyrimidones are reported. The multistep sequence involves the initial bromination of dihydropyrimidones precursors (DHPMs, Biginelli compounds) at the C6-methyl position, using a recyclable polymer-supported brominating agent under rapid flow-through conditions (residence time of 1 min). The 6-bromomethyldihydropyrimidone intermediates were subsequently subjected to a microwave-assisted azidation step (25 min), providing the key 6-azidomethyldihydropyrimidone precursors. In the final step of the sequence, the azides were treated with terminal acetylenes under Cu(I) catalysis (azide-acetylene ligation, "click chemistry") to provide the target 6-(1,2,3-triazol-1-yl)-dihydropyrimidones in a regiospecific fashion (1,4-triazoles) in moderate overall yield utilizing controlled microwave irradiation (20 min). In total, a library of 27 compounds was prepared with 4 points of diversity.
authors.affiliation: Institute of Chemistry, Karl-Franzens-University Graz, Heinrichstrasse 28, A-8010 Graz, Austria.
authors.forename: Bogdan
authors.initials: B
authors.lastname: Khanetskyy
authors.forename: Doris
authors.initials: D
authors.lastname: Dallinger
authors.forename: C Oliver
authors.initials: CO
authors.lastname: Kappe