What's Hot, What's Not: The Trends of the Past 20 Years in the Chemistry of Odorants

Abstract

This review is the sequel to the 2000 report on the recent advances in the chemistry of odorants and it summarizes the developments in fragrance chemistry over the past 20 years. Following the olfactory spectrum set out in that report, trendsetting so‐called captive odorants (patent‐protected ingredients unavailable to the market) are presented according to the main odor families: “fruity”, “marine”, “green”, “floral”, “spicy”, “woody”, “amber”, and “musky”. The design of odorants, their chemical synthesis, and their use in modern perfumery are illustrated with prominent examples. Featured are new fruity odorants that provide signature in the top note, as well as precursor technology. In the green domain, focus is on leafy notes and green pear. New benzodioxepines and benzodioxoles have modernized the marine family and required a revision of the existing olfactophore models. The replacement of Lilial and Lyral kept the industry busy in the floral domain with a plethora of new “muguets”. There was continued activity in the domain of rose odorants, especially in the area of rose ketones. Biotechnology became significant, for example, with Clearwood and Ambrofix, and the principal odorants of vetiver oil in the woody family have been found. Fourth and fifth families of musk odorants were also discovered and populated. Thus, new avenues for further explorations into fragrance chemistry have been opened.

Water co-catalysis in aerobic olefin epoxidation mediated by ruthenium oxo complexes

“…2a) and their corresponding trans-dioxo ruthenium complexes for a systematic study of their catalytic behaviour in olen epoxidation under various conditions. When [(L1)Ru VI (O) 2 ] was tested for the aerobic epoxidation of styrene (1) in CDCl 3 at 30 °C using 8% O 2 in N 2 (40 bar) only ∼30% of styrene oxide (1a) was obtained at 1 mol% catalyst loading (Fig. 2b, entry 1), a result which is consistent with previous reports.…”

Water co-catalysis in aerobic olefin epoxidation mediated by ruthenium oxo complexes

“…2a) and their corresponding trans-dioxo ruthenium complexes for a systematic study of their catalytic behaviour in olen epoxidation under various conditions. When [(L1)Ru VI (O) 2 ] was tested for the aerobic epoxidation of styrene (1) in CDCl 3 at 30 °C using 8% O 2 in N 2 (40 bar) only ∼30% of styrene oxide (1a) was obtained at 1 mol% catalyst loading (Fig. 2b, entry 1), a result which is consistent with previous reports.…”

Antagonistic interactions between odorants alter human odor perception

“…2C). In contrast, Iso E super (tetramethyl acetyloctahydronaphthalen) 31,32 , which is one of the most commonly used ketone fragrances for deodorant, did not show potent antagonistic effects on OR2T11 (Fig. 2B).…”

Synthesis of 1,4‐Cyclohexadiene Carboxylates through a Formal [2+4]‐Cycloaddition of Propiolates under Cobalt Catalysis

“…While 6a, 6h and 6k maintain the saffron-like spicy note of ethyl safranate, the C(5) chain of 6q triggers transitions towards heavier plumy, damascone-like notes. [1] Still, the classical green apple and fruity tonality is present for all the structures assessed ( Figure 2).…”

“…The olfactive assessment of a series of final products 6a , 6b , 6e , 6h , 6k , 6l , 6m and 6q indicate that these unsaturated cyclohexyl esters turn into the expected green fruity, safranate‐like direction. While 6a , 6h and 6k maintain the saffron‐like spicy note of ethyl safranate, the C(5) chain of 6q triggers transitions towards heavier plumy, damascone‐like notes [1] . Still, the classical green apple and fruity tonality is present for all the structures assessed ( Figure 2).…”

Water co-catalysis in aerobic olefin epoxidation mediated by ruthenium oxo complexes

“…2a) and their corresponding trans-dioxo ruthenium complexes for a systematic study of their catalytic behaviour in olen epoxidation under various conditions. When [(L1)Ru VI (O) 2 ] was tested for the aerobic epoxidation of styrene (1) in CDCl 3 at 30 °C using 8% O 2 in N 2 (40 bar) only ∼30% of styrene oxide (1a) was obtained at 1 mol% catalyst loading (Fig. 2b, entry 1), a result which is consistent with previous reports.…”

Antagonistic interactions between odorants alter human odor perception

“…2C). In contrast, Iso E super (tetramethyl acetyloctahydronaphthalen) 31,32 , which is one of the most commonly used ketone fragrances for deodorant, did not show potent antagonistic effects on OR2T11 (Fig. 2B).…”

Synthesis of 1,4‐Cyclohexadiene Carboxylates through a Formal [2+4]‐Cycloaddition of Propiolates under Cobalt Catalysis

“…While 6a, 6h and 6k maintain the saffron-like spicy note of ethyl safranate, the C(5) chain of 6q triggers transitions towards heavier plumy, damascone-like notes. [1] Still, the classical green apple and fruity tonality is present for all the structures assessed ( Figure 2).…”

“…The olfactive assessment of a series of final products 6a , 6b , 6e , 6h , 6k , 6l , 6m and 6q indicate that these unsaturated cyclohexyl esters turn into the expected green fruity, safranate‐like direction. While 6a , 6h and 6k maintain the saffron‐like spicy note of ethyl safranate, the C(5) chain of 6q triggers transitions towards heavier plumy, damascone‐like notes [1] . Still, the classical green apple and fruity tonality is present for all the structures assessed ( Figure 2).…”

Water co-catalysis in aerobic olefin epoxidation mediated by ruthenium oxo complexes

“…2a) and their corresponding trans-dioxo ruthenium complexes for a systematic study of their catalytic behaviour in olen epoxidation under various conditions. When [(L1)Ru VI (O) 2 ] was tested for the aerobic epoxidation of styrene (1) in CDCl 3 at 30 °C using 8% O 2 in N 2 (40 bar) only ∼30% of styrene oxide (1a) was obtained at 1 mol% catalyst loading (Fig. 2b, entry 1), a result which is consistent with previous reports.…”

Antagonistic interactions between odorants alter human odor perception

“…2C). In contrast, Iso E super (tetramethyl acetyloctahydronaphthalen) 31,32 , which is one of the most commonly used ketone fragrances for deodorant, did not show potent antagonistic effects on OR2T11 (Fig. 2B).…”

Synthesis of 1,4‐Cyclohexadiene Carboxylates through a Formal [2+4]‐Cycloaddition of Propiolates under Cobalt Catalysis

“…While 6a, 6h and 6k maintain the saffron-like spicy note of ethyl safranate, the C(5) chain of 6q triggers transitions towards heavier plumy, damascone-like notes. [1] Still, the classical green apple and fruity tonality is present for all the structures assessed ( Figure 2).…”

“…The olfactive assessment of a series of final products 6a , 6b , 6e , 6h , 6k , 6l , 6m and 6q indicate that these unsaturated cyclohexyl esters turn into the expected green fruity, safranate‐like direction. While 6a , 6h and 6k maintain the saffron‐like spicy note of ethyl safranate, the C(5) chain of 6q triggers transitions towards heavier plumy, damascone‐like notes [1] . Still, the classical green apple and fruity tonality is present for all the structures assessed ( Figure 2).…”