Regioselective addition of Ti enolates to conjugated enones: New insights into the mechanism based on experimental and DFT investigation. Issue 23 (7th June 2018)

• Record Type: Journal Article
• Authors: Wu, Chenggui; Mao, Shanjian; Deng, Guisheng; Qiu, Yongge
• Is Part Of: Tetrahedron. Volume 74:Issue 23(2018)
• Page Start: 2819
• Page End: 2824
• Publication Date: 2018-06-07
• Subjects: Ti(IV) enolates -- Enones -- α-Diazo-β-keto phosphonates -- Regioselectivity -- DFT; PTEJTDDRKIEHGV-FOCLMDBBSA-N -- HYBFPCJCZCNSGY-VAWYXSNFSA-N -- LRXJRWJDCLDHIQ-UHFFFAOYSA-N -- UHILAOMLDBBGRI-UHFFFAOYSA-N -- KRAJNFFXAZMYFP-ACCUITESSA-N -- IOQGPWFVQHYIFF-MDZDMXLPSA-N -- ARGCWKATSCCEFU-UHFFFAOYSA-N -- ARGCWKATSCCEFU-UHFFFAOYSA-N -- TXZKVULZRXFWQV-CMDGGOBGSA-N -- CXRGTQCAUUUOGD-OZGAEJQKSA-N -- PGNOJUGGJSZFQW-UHFFFAOYSA-N -- CXRGTQCAUUUOGD-OGMPJXADSA-N; Chemistry, Organic -- Periodicals; 547.005
• DOI: 10.1016/j.tet.2018.01.002
• Languages: English
• ISSNs: 0040-4020

Abstract

Abstract: The regioselective addition mechanism of the Ti(IV) enolates derived from α-diazo-β-keto carbonyl compounds and α-diazo-β-keto phosphonates to conjugated enones has been studied on the basis of a hypothetical bridging chloride-controlled theory, by density functional theory (DFT), and experimentally. The DFT results indicate that, for the Ti(IV) enolate3 derived from α-diazo-β-keto carbonyl compounds, the free energy of the bridging chloride-controlled 1, 2-addition transition state is 2.4 kcal/mol higher than that of 1, 4-addition, and the calculated enthalpies of 1, 2-addition is 4.36 kcal/mol more than that of 1, 4-addition. For the Ti(IV) enolate4 derived from α-diazo-β-keto phosphonates, in contrary, the free energy of the bridging chloride-controlled 1, 2-addition transition state is 1.1 kcal/mol lower than that of 1, 4-addition, and the calculated enthalpy of 1, 2-addition is 3.46 kcal/mol less than that of 1, 4-addition. Our findings demonstrate that the nucleophilic addition of these Ti(IV) enolates to conjugated enones was carried out not only kinetically but also irreversibly for the first time. Graphical abstract: