An expedient synthesis of racemic combretastatin and isocombretastatin

The stilbenoid constituents of Combretum caffrum possess pronounced antineo plastic and antimitotic activities. The most potent agents are R (-) combre tastatin 1, and combretastatins A-1 to A-4. A novel and simple method for t he synthesis of +/- 1 and isocombretastatin 5 in which an appropriately sub stituted 1, 3-diarylpropanoid is transformed into a stilbenoid is described . The key step involves the alkali induced rearrangement of chalcone epoxid e 9 to alpha -hydroxy acid 10 and that is followed by oxidative decarboxyla tion and reduction.