TY - JOUR
T1 - 1-Acetylvinyl acrylates
T2 - New captodative olefins bearing an internal probe for the evaluation of the relative reactivity of captodative against electron-deficient double bonds in Diels-Alder and Friedel-Crafts reactions
AU - Herrera, Rafael
AU - Jiménez-Vázquez, Hugo A.
AU - Delgado, Francisco
AU - Söderberg, Björn C.G.
AU - Tamariz, Joaquín
PY - 2005
Y1 - 2005
N2 - The captodative olefins 1-acetylvinyl esters of methacrylic and trans-crotonic acids, 3a and 3b, have been prepared. The presence of a second double bond in the molecule, acting as an internal probe, allowed us to compare their relative reactivity in Diels-Alder and Friedel-Crafts reactions. The reactivity was evaluated with cyclopentadiene (6) as diene in Diels-Alder cycloadditions, and with furan (9) and thiophene (10) as heteroaromatic Friedel-Crafts substrates. In both processes, the captodative enone double bond proved to be more reactive than that in the acrylic moiety. FMO theory accounted for this chemoselectivity as a consequence of the major π contribution of the enone to the LUMO of these molecules. The slight exo stereoselectivity observed in the cycloaddition to 6 parallels the higher stability of the corresponding transition state, according to the results of B3LYP/ 6-311G(d,p) calculations.
AB - The captodative olefins 1-acetylvinyl esters of methacrylic and trans-crotonic acids, 3a and 3b, have been prepared. The presence of a second double bond in the molecule, acting as an internal probe, allowed us to compare their relative reactivity in Diels-Alder and Friedel-Crafts reactions. The reactivity was evaluated with cyclopentadiene (6) as diene in Diels-Alder cycloadditions, and with furan (9) and thiophene (10) as heteroaromatic Friedel-Crafts substrates. In both processes, the captodative enone double bond proved to be more reactive than that in the acrylic moiety. FMO theory accounted for this chemoselectivity as a consequence of the major π contribution of the enone to the LUMO of these molecules. The slight exo stereoselectivity observed in the cycloaddition to 6 parallels the higher stability of the corresponding transition state, according to the results of B3LYP/ 6-311G(d,p) calculations.
KW - Captodative olefins
KW - Diels-Alder cycloaddition
KW - Friedel-Crafts
KW - Transition state calculations
UR - http://www.scopus.com/inward/record.url?scp=23744434175&partnerID=8YFLogxK
U2 - 10.1590/S0103-50532005000300021
DO - 10.1590/S0103-50532005000300021
M3 - Artículo
SN - 0103-5053
VL - 16
SP - 456
EP - 466
JO - Journal of the Brazilian Chemical Society
JF - Journal of the Brazilian Chemical Society
IS - 3 A
ER -