Microwave accelerated synthesis of novel spiro heterocycles

Abstract

Interaction of 3,3-dibromo carbostyril 1 with substituted triazoles 2, amidinothiocarbamides 4, amidinocarbamide 6, guanidines 8 and thiocarbohydrazide 10 furnishes spiro(1'H-2',4'-dioxo-6',8'-disubstituted quinoline)-4H-1,3,4-thiadiazolo[2,3-d]-(3-substituted)-1,2,4-triazole 3, 2-guanidino/substituted guanidino-spiro(1'H-2',4'-dioxo-6',8'-disubstituted quinoline)-1,3-thiazetidin-2-ene 5, 2-guanidino-spiro(1'H-2',4'-dioxo-6',8'-disubstituted quinoline)-1,3-oxazetidin-2-ene 7, 1H-2-amino/N-substituted amino-spiro(1'H-2',4'-dioxo-6',8'-disubstituted quinoline)-1,3-diazetidin-2-ene 9, 8,9-(2',4'-disubstituted)-benzo-1-thia-2-hydrazino-3,4,7-triaza-4,7-dihydro-6,10-dioxo-spiro [4,5] dec-2-ene 11 respectively. The salient features of the microwave approach are rapid reaction rates, cleaner reaction condition and enhancement in chemical yields compared to classical method. The structures of synthesized compounds have been confirmed by IR, ¹H and ¹³C NMR.