Paternò-Büchi reaction between furan and heterocyclic aldehydes: oxetane formation vs. metathesis.
The photochemical reaction of 2-substituted heterocyclic aldehydes with furan gave the corresponding exo oxetane derivatives through the excited triplet state. However, in situ the oxetane derivatives were converted through a metathesis reaction into the corresponding Z,E-butadienyl formate derivatives. On the contrary, 3-substituted heterocyclic aldehydes gave the corresponding exo oxetane derivatives. The effect of 2-substituted heterocyclic ring in order to facilitate the metathesis reaction is explained considering the possible participation of the pi aromatic orbitals in the oxetane C-O bond cleavage.
D'Auria
Maurizio
M
Dipartimento di Chimica, Università della Basilicata, Via N. Sauro 85, 85100, Potenza, Italy.
Racioppi
Rocco
R
Viggiani
Licia
L