Divergent Pathways and Competitive Mechanisms of Metathesis Reactions between 3-Arylprop-2-ynyl Esters and Aldehydes: An Experimental and Theoretical Study

0431791 - ÚOCHB 2015 RIV DE eng J - Článek v odborném periodiku
Trujillo, Cristina - Sanchez-Sanz, Goar - Karpavičiene, I. - Jahn, Ullrich - Čikotiene, I. - Rulíšek, Lubomír
Divergent Pathways and Competitive Mechanisms of Metathesis Reactions between 3-Arylprop-2-ynyl Esters and Aldehydes: An Experimental and Theoretical Study.
Chemistry - A European Journal. Roč. 20, č. 33 (2014), s. 10360-10370. ISSN 0947-6539. E-ISSN 1521-3765
Grant CEP: GA ČR(CZ) GA14-31419S
Grant ostatní: European Social Fund(XE) VP1-3.1-SMM-07 K-01-002
Institucionální podpora: RVO:61388963
Klíčová slova: 3-arylprop-2-ynyl esters * density functional calculations * isotopic labeling * ketones * Morita-Baylis-Hillman adducts
Kód oboru RIV: CF - Fyzikální chemie a teoretická chemie
Impakt faktor: 5.731, rok: 2014

Mechanistic studies of the reaction between 3-arylprop-2-ynyl esters and aldehydes catalyzed by BF3Et2O were performed by isotopic labeling experiments and quantum chemical calculations. The reactions are shown to proceed by either a classical alkyne-carbonyl metathesis route or an unprecedented addition-rearrangement cascade. Depending on the structure of the starting materials and the reaction conditions, the products of these reactions can be Morita-Baylis-Hillman (MBH) adducts that are unavailable by traditional MBH reactions or E- and Z-alpha, beta-unsaturated ketones. O-18-Labeling studies suggested the existence of two different reaction pathways to the products. These pathways were further examined by quantum chemical calculations that employed the DFT(wB97XD)/6-311+G(2d,p) method, together with the conductor-like screening model for realistic solvation (COSMO-RS). By using the wB97XD functional, the accuracy of the computed data is estimated to be 1-2kcalmol(-1), shown by the careful benchmarking of various DFT functionals against coupled cluster calculations at the CCSD(T)/aug-cc-pVTZ level of theory. Indeed, most of the experimental data were reproduced and explained by theory and it was convincingly shown that the branching point between the two distinct mechanisms is the formation of the first intermediate on the reaction pathway: either the four-membered oxete or the six-membered zwitterion. The deep mechanistic understanding of these reactions opens new synthetic avenues to chemically and biologically important alpha, beta-unsaturated ketones.
Trvalý link: http://hdl.handle.net/11104/0236413