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Communication | Regular issue | Vol 12, No. 6, 1979, pp.757-760
Published online, 1st January, 1970
DOI: 10.3987/R-1979-06-0757
The Use of Quinizarin Diboroacetate as a Dipolarophile in the Synthesis of Fused Tertacyclic Isoxazoles and Pyrazoles

Alan M. Birch, Anthony J. H. Mercer,* and Colin W. Greenhalgh

*School of Analytical and Biological Chemistry, Kingston Polytechnic, Kingston-on-Thames, KT1 2EE, U.K.


Quinizarin diboroacetate undergoes [3 + 2] cycloaddition reactions with benzonitrile oxide to give an anthra[2,3-d]isoxazole (2) and with diphenyldiazomethane to form an anthra[2,3-c]pyrazole (4) which decomposes at 250° to a 13H-indenoanthracene (8); the diphenyldiazomethane dihydroadduct (9; R=B(OAc)2) undergoes thermal decomposition at room temperature to give 2-(diphenylmethyl)quinizarin (11).