1,3-dipolar cycloaddition route to novel isoxazole-type derivatives related to combretastatin A-4

A series of compounds related to combretastatin A-4, containing a five-membered heterocyclic ring interposed between the two phenyl groups have been Prepared. Synthetic approach involves 1,3-dipolar cycloaddition of various 3,4,5-trimethoxyphenyl units with an in situ generated nitrile oxide from a suitable aldoxime using sodium hypochlorite. Depending oil the nature of the dipolarophile, 3,5-diarylisoxazole derivatives obtained along with the 3,4-regioisomeric isomers. (C) 2004 Elsevier Ltd. All rights reserved.