Recent Optimization Highlights of the Georgywood Process

Alternative procedures to the industrial process by which Georgywood® is presently prepared on a multiton scale have been investigated. These give the crucial homomyrcene precursor 5a and target compound 1 with greatly improved selectivities. Homomyrcene 5a was prepared with much better yield and selectivity by converting methylgeraniol 4 into an allylic carbonate, followed by a solvent-free palladium-catalyzed 1,4-elimination. In the final 1,5-diene cyclization, excellent selectivities were achieved by replacing Brønsted acid H3PO4 by meAlcl2. This requires preparation, safety measures and an in-situ conversion of stoichiometric amounts of the pyrophoric Lewis acid. Recently, an in situ preparation of MeAICI2 from AIMe3 and its catalytic use became possible.