The chemistry of thujone. XVI. Versatile and efficient routes to safronitrile, β-cyclogeranonitrile, β-cyclocitral, damascones, and their analogues

Thujone, a waste by-product of the Canadian forest industry, has been utilized as a starting material to develop a versatile synthetic route to the damascones (rose oil ketones) and related analogues. The synthetic sequence provides a route to β-cyclocitral ( 45 ), the latter having been previously converted to β-damascone ( 2 ). In addition, thujone-derived intermediates are converted to β-damascenone ( 48 ) and to intermediates that can be utilized for the preparation of damascone analogues. In conjunction with the above, an efficient route to safronitrile ( 42 ), β-cyclogeranonitrile ( 43 ), and β-cyclocitral ( 45 ) from 2,6-dimethylcyclohexanone has been developed. In summary, these studies afford an attractive versatile route to these important perfumery materials.