Cp. Sar et al., SYNTHESIS, OXIDATION AND CLAISSEN REARRANGEMENT OF 4-(ALLYLOXY)PHENYL-1,4-DIHYDROPYRIDINES AND 4-(ALLYLOXY)PHENYL-1,4-DIHYDROPYRIMIDINES, ACH, models in chemistry, 131(3-4), 1994, pp. 363-376
1,4-Dihydropyridines and -pyrimidines can be oxidized conveniently to
pyridine and pyrimidine with active MnO2 with or without cleavage of t
he 4-substituent. In a TiCl4 catalyzed reaction ortho-Claisen rearrang
ement takes place with both 4-(2-allyloxy)phenyl 1,4-dihydropyridines
and -1,4-dihydropyrimidines.