The shown animation (made in Flash 4) illustrates one method of synthesis of methyl 2,4-dihydroxy-3,6-dimethylbenzoate, the most important odour component in Oakmoss, Evernia prunastri (Usneaceae).

It has a very powerful odour - earthy, woody, phenolic - characteristic of some lichenes, and is much used in perfumery, in low concentration.

1) Sonn A, Berichte 1929;62B:3012
2) Eur.Pat. 133,960 (Chem.Abstr 1986;105:226057x)
3) Bauer K, Garbe D, Surburg H (1990) Common fragrance and flavor materials. Preparation, properties and uses. 2'nd rev. ed. VCH Germany.

This method is suitable for small scale laboratory synthesis. The industrial method involves a Friedel-Crafts condensation of propionyl chloride with propene, followed by a Michael-like condensation with dimethyl malonate. The aromatization is achieved with sulphuric acid.
(Daniel Joulain, Robertet S.A. - personal communication)

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