title: [DBU-H]+ and H2 o as effective catalyst form for 2,3-dihydropyrido[2,3-d]pyrimidin-4(1H)-ones: A DFT Study.
abstract: DFT investigations are carried out to explore the effective catalyst forms of DBU and H(2)O and the mechanism for the formation of 2,3-dihydropyrido[2,3-d]-pyrimidin-4(1H)-ones. Three main pathways are disclosed under unassisted, water-catalyzed, DBU and water cocatalyzed conditions, which involves concerted nucleophilic addition and H-transfer, concerted intramolecular cyclization and H-transfer, and Dimroth rearrangement to form the product. The results indicated that the DBU and water cocatalyzed pathway is the most favored one as compared to the rest two pathways. The water donates one H to DBU and accepts H from 2-amino-nicotinonitrile (1), forming [DBU-H](+) -H(2)O as effective catalyst form in the proton migration transition state rather than [DBU-H](+) -OH(-) . The hydrogen bond between [DBU-H](+) ···H(2)O···1(-) decreases the activation barrier of the rate-determining step. Our calculated results open a new insight for the green catalyst model of DBU-H(2)O.
authors.affiliation: Department of Chemistry, Northeast Normal University, Renmin Street 5268#, Changchun, 130024, China.
authors.forename: Haiyan
authors.initials: H
authors.lastname: Yuan
authors.affiliation: Department of Chemistry, Northeast Normal University, Renmin Street 5268#, Changchun, 130024, China.
authors.forename: Jingping
authors.initials: J
authors.lastname: Zhang
keywords: DBU; catalyst form [DBU-H]+-H2O; density functional theory; mechanism; water