Synthesis of some new spirocyclic β-lactam and spirocyclic thiazolidin-4-one derivatives

Abstract

Selective oxidation of 4-amino-2-methyl-5,10-dioxo-1,5,10,10a-tetrahydrobenzo[g]-quinoline-3-carbonitrile (1) with selenium dioxide provided, 4-amino-2-formyl-5,10-dioxo-1,5,10,10a-tetrahydrobenzo[g]quinoline-3-carbonitrile (2). The one-pot reaction of compound 2 with ethyl cyanoacetate and thiourea in ethanol yielded 4-amino-2-(5-cyano-6-oxo-2-thioxo-1,2,3,6-tetrahydropyrimidin-4-yl)-5,10-dioxo-1,5,10,10a-tetrahydrobenzo[g]-quinoline-3-carbonitrile (3). The cycloaddition reaction of chloroacetic acid with compound 3 yielded 7-(4-amino-3-cyano-5,10-dioxo-1,5,10,10a-tetrahydrobenzo-[g]quinolin-2-yl)-3,5-dioxo-3,5-dihydro-2H-thiazolo[3,2-a]pyrimidine-6-carbonitrile (4). Moreover, Ehrlich-Sachs condensation reaction of compound 4 with the aromatic nitroso compounds 5a-c gave the corresponding new Schiff bases 6a-c. Staudinger's ketene-imine cycloaddition reaction of compounds 6a-c with chloroacetyl chloride afforded the corresponding spiro[chloroazetidinethiazolopyrimidine] derivatives, 7a-c. On the otherhand, cycoladdition reaction of thioglycolic acid with Schiff bases 6a-c yielded the corresponding spiro[thiazolidinethiazolopyrimidine] derivatives, 8a-c. Structures of the new compounds were elucidated by compatible analytical and spectroscopic (IR, ¹H NMR and MS) measurements. Moreover, the reaction mechanisms that account for formation of the synthesized compounds have been discussed.