Theoretical study of the highly diastereoselective 1,3-dipolar cycloaddition of 1,4-dihydropyridine-containing azomethine ylides to [60]fullerene (Prato's reaction).
The 1,3-dipolar cycloaddition of azomethine ylides bearing the biologically active 1,4-dihydropiridine ring to C(60) was investigated by means of quantum mechanical calculations at the semiempirical AM1 and DFT (B3LYP/6-31G) methods. The presence of two chiral centers and one chiral axis in the resulting fulleropyrrolidines leads to four possible [6,6] cycloaddition products. Formation of atropoisomers has also been considered. The transition-state structures were computed for the four different cycloaddition pathways to find out the lowest activation energy stereoisomer. In all cases, a frequency analysis and an IRC calculation were carried out to fully characterize the located transition-state structures. AM1 results and single-point energy calculations at the B3LYP/6-31G//AM1 level for the four transition-state structures yield activation energies values below 5 kcal/mol.
Alvarez
Amaury
A
Laboratorio de Síntesis Orgánica, Facultad de Química, Universidad de La Habana, 10400 City of Havana, Cuba.
Ochoa
Estael
E
Verdecia
Yamila
Y
Suárez
Margarita
M
Solá
Miquel
M
Martín
Nazario
N