Synthesis of Isochromans From Anacardic Acids Obtained From Cashew Nutshell Liquid (CNSL) and Their Antimicrobial Activity.

The synthesis of racemic isochromans from cashew nut shell liquid (CNSL) derived anacardic acids is described. Two key steps for the synthesis of the isochromans were utilized. (i) The benzylic bromination of methyl 2-methoxy-6-pentadecylbenzoate was accomplished with N-bromosuccinimide in the green solvent tert-butyl acetate to afford methyl 2-methoxy-6-(pentadec-1-en-1-yl)benzoate. (ii) Exposure of the secondary alcohol 1-(2-methoxy-6-(pentadec-1-en-1-yl)phenyl)ethanol to potassium tert-butoxide resulted in the formation of the isochroman, trans-8-methoxy-1-methyl-2-tridecylisochroman. In a similar manner, the related isochroman, trans-8-methoxy-1,3-dimethylisochroman, could be synthesized. Selected antifungal and antibacterial testing showed moderate activities.