Open AccessRecent Optimization Highlights of the Georgywood Process
Author(s) -
JeanPierre Barras,
Bernadette Bourdin,
Fridtjof Schröder
Publication year - 2006
Publication title -
chimia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.387
H-Index - 55
eISSN - 2673-2424
pISSN - 0009-4293
DOI - 10.2533/chimia.2006.574
Subject(s) - catalysis , allylic rearrangement , yield (engineering) , lewis acids and bases , selectivity , solvent , chemistry , stoichiometry , palladium , organic chemistry , diene , combinatorial chemistry , materials science , metallurgy , natural rubber
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.