Chemistry of Heterocycles. Part-II. 6 π Electrocyclisation of Aza-1,3,5- hexatrienes and 1,3,5,7-Octatetraenes to Pyridines

Department of Chemistry, Kakatiya University, Warangal-506 009

Manuscript received 19 December 1983, revised 9 July 1984, accepted 18 January 1985

4-Benzalamino-3-methyl-5-styrylisoxazoles (4) have been thermally cyclised to 3-methyl-5,6-diaryl-4,5-dihydroisoxazolo[4,5-b]ipyridines (6). The vinylogue of 4, viz. 3-methyl-4-cinnamylideneamino-5-styrylisoxazole (7) has also given the pyridine (9) instead of the expected azocine (8). The isoxazole Schiff bases have been obtained from the aminoisoxazole (3) by condensation with aromatic aldehydes. Ir, pmr and mass spectra have been discussed in support of the structures.