Abstract A four-step synthesis of methyl 6-formyl-2-hydroxy-4-methoxy-3-(3-methylbut-2-en-1-yl)benzoate (11) that can be used as building block for a facilesynthesis of cajaninstilbene acid and its derivatives is reported. The synthesis of cajaninstilbene acid was accomplished in six steps with an overall yield of 20% starting from commercial materials by a synthesis whose key steps are TiCl4-mediated