Isosafrole via Wittig Olefination of Piperonal

[Rhodium]

3,4-(Methylenedioxy)--methylstyrene (Isosafrole)¹

To a well stirred suspension of ethyltriphenylphosphonium bromide (7.5 g, 20.2 mmol) in dry THF (100 mL), a solution of n-butyllithium (12.6 mL of a 1.6 M solution in hexane, 20.2 mmol) was added dropwise over a period of 30 min at 0°C. The mixture was warmed to room temperature and stirred for 60 min. A solution of piperonal (3.0 g, 20.0 mmol) in THF (25 mL) was then slowly added and the resulting mixture left stirring for a further 6 h. Water (100 mL) was added, the organic layer was separated, the aqueous phase extracted twice with diethyl ether and the combined organic phases were finally dried over MgSO₄. After filtration and evaporation of the solvents the residue was eluted from silica gel with CH₂Cl₂ to remove phosphine oxide, and the residue was purified by vacuum distillation to give 3.0 g (18.5 mmol, 92%) of a mixture of cis- and trans-isosafrole (1:10) as a colourless oil, bp 121°C/15 Torr (lit.2 bp 123°C/11.5 Torr), 3.0 g (18.5 mmol, 92%) as a colourless oil, mixture of cis- and trans-isosafrole (1:10).

References:
1: J.Chem.Soc.Perkin Trans.1, 19, 2393-2397 (2001)
2: Chem. Ber. 42, 3008 (1909)

[GC_MS]

And not to mention that it will work for all our other beloved substituted benzaldehydes as well   .
Ave Hive, synthetisandi te salutant!