Abstract
Ambergris, an excretion product of sperm whales, has been a valued agent in the formulation of perfumes. The composition of ambergris consists of two major components: 40–46% cholestanol type steroids and approximately 25–45% of a triterpenoid known as ambrein. Ambergris undergoes oxidative decomposition in the environment to result in odorous compounds, such as ambraoxide, methylambraoxide, and ambracetal. Its oxidized form, ambrafuran (IUPAC name: 3a,6,6,9a-tetramethyl-2,4,5,5a,7,8,9,9b-octahydro-1H-benzo[e][1]benzofuran), is a terpene furan with a pleasant odor and unique olfactive and fixative properties. The current state of the fragrance industry uses ambrafuran materials entirely from synthetic or semisynthetic sources. However, natural compounds with the potential to be converted to ambergris-like odorants have been extracted from several different types of plants. Here we review plant terpenoids suitable as starting materials for the semisyntheses of ambrafuran or intermediates, such as ambradiol, that can be used in biocatalytic transformations to yield ambrafuran.
Highlights
Ambergris, an excretion product of sperm whales, has been a valued agent in the formulation of perfumes
In the case of the labdanes, only a limited number are obtainable in large amounts from plantis a rich source of labdanes, important secondary metabolites are synthesized by diterpene products, limiting their use as starting materials
Labdanolic acid has the potential to serve as an inexpensive starting material for the synthesis of ambrafuran, since, after oxidative degradation of the C-9 side chain, suitable synthons for (−)-ambrafuran synthesis are generated [16]. (−)-Ambrafuran can be obtained from labdanolic acid (38) in seven steps, as indicated in Figure 12 below
Summary
2.1. (+)-Carvone (+)-Carvone is a monocyclic terpene and dominant constituent of seed oils of caraway (Carum is a monocyclic dominant constituent seed oils of caraway (Carum carvi) (+)-Carvone and dill (Anethum graveolens),terpene as well and as leaves of members of theofLamiaceae family. Carvone is carvi) and dill (Anethum graveolens), as well as pure leaves of members. Fromfor monocyclic (S)-(+)-carvone (3), bicyclic intermediates (4) were synthesized. From monocyclic (3), bicyclic such as decalone (4) were from carvone using two annulation methodologies, i.e.,intermediates the Diels–Alder reaction and the Robinson synthesized from carvone using two annulation methodologies, i.e., the. The conversion of the decalone derivative to a hydroxy ketone (5) involved the conversion of the allyl moiety into a hydroxy ethylene moiety and the conversion of the Molecules. A methyl group and double conversion of the allyl moiety into a hydroxy ethylene moiety and the conversion of the isopropenyl bond was introduced to result in the unsaturated alcohol (6) (Figure 2) that was cyclized using isopropenyl group into carbonyl functionality. Verstegen-Haaksma et al [17]
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