Abstract Vanillin (1) and piperonal (3) reacted with ylidenetriphenylphosphoranes 4a-f in boiling toluene following the Wittig mechanism to give the ethylenes 5a-f and 7a-f. Similarly, ethylenes 8c-f were produced when orrho-vanillin (2) was allowed to react with 4c-f. The reaction of aldehyde (2) with the P-ylides 4a, b yielded the Wittig products 8a, b and 8- methoxycoumarin (10). Triphenylphosphine oxide (TPPO, 6) was isolated and identified in ...