The synthesis of (-)-Ambrox® starting from labdanolic acid

Iododecarboxylation of labdanolic acid (1), followed by dehydrohalogenation led to alkenes 4 and 12. Both compounds were converted into (1R,2R,4aS,8aS)-1-(2-hydroxyethyl)-2,5,5,8a-tetramethyldecahydro-2-naphthalenol (8), which was transformed via cyclization into (-)-Ambrox((R)) (9). (C) 2001 Elsevier Science Ltd. All rights reserved.