Efficient synthesis of some novel spiro heterocycles containing thiazole, oxazole, thiadiazole and triazolo-thiadiazole moiety under microwave irradiation

摘要

5,5-Dimethyl cyclohexane-1,3-dione 1 was treated with twice the molar quantity of bromine in glacial acetic acid to yield 2,2-dibromo-5,5-dimethyl cyclohexane-1,3-dione 2. The dibromo compound 2 was subjected to reaction with substituted 2-aminothiophenols, 2-aminophenol, thiocarbohydrazones, thiosemicarbazones and triazoles to furnish spiro-(2',6'-dioxo-4',4'-dimethyl cyclohexane)-6-substituted-1,3-benzothiazole 3, spiro-(2',6'-dioxo-4',4'-dimethyl cyclohexane)-6-substituted-1,3-benzoxazole 4, Schiff base of 1-thia-2-hydrazino-3,4-diaza-4H-6,10-dioxo-7,9-dihydro-8,8-dimethyl-spiro[4 5]dec-2-ene 5, Schiff base of 1-thia-2-amino-3,4-diaza-4H-6,10-dioxo-7,9-dihydro-8,8-dimethyl-spiro[4,5]dec-2-ene 6 and spiro-(2',6'-dioxo-4',4'-dimethyl cyclohexane)-1,3,4-thiadiazolo[2,3-d]-4-substituted-1,2,4-triazoles 7 respectively. All the final desired compounds have been synthesized by ensuing the microwave irradiation technique as well as classical thermal method. The structures of the newly synthesized compounds have been established by analytical and spectral methods.