Solvent dependent photobehaviour of some 2-aryl-2-bromo-1H-indene- 1,3(2H)-diones

Satbir Mor and Som Nath Dhawan

Abstract

Photoirradiation of deoxygenated solutions of some 2-aryl-2-bromo-1H-indene-1,3(2H)-diones (2) under N2 atmosphere in anhydrous alcohol and acetone has been studied. The photoreaction is envisaged to occur through β- cleavage in which homolytic cleavage of C2–Br bond occurs preferentially to furnish the corresponding resonance stabilized 2-aryl-1H-indene-1,3(2H)-dione free radicals (3) which lead to the formation of a mixture of photoproducts depending upon the solvent employed, i.e. 2-aryl-2-ethoxy-1H-indene-1,3(2H)-diones (4), 2,2'-diaryl- 1H,1'H-2,2'-biindene-1,1',3,3'(2H,2'H)-tetrones (5) and (Z)-2-(aryl)-2-((aryl)(3-oxoisobenzofuran-1(3H)- ylidene)methyl)-1H-indene-1,3(2H)-diones (6) in anhydrous alcohol and 2-aryl-1H-indene-1,3(2H)-diones (1) and bromoacetone (8) in dry acetone. The structural confirmation of the synthesized products was carried out on the basis of spectral (ir, 1H NMR and mass) as well as elemental analysis results.

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