Y-Damascone

Amrollah-Madjdabadi and Stella used a similar approach for the rapid and concise synthesis of y-damascone (30) in three steps starting from allyl bromide (28) and dimethylaminoacetonitrile (29).21 These investi-... 

Snowden has used the terminus fragmentation in his earlier papers for the -cleavage of homoallylic alkoxides (Scheme 72). Such a reaction sequence (Scheme 73) has been used in particular for the synthesis of damascenes e.g. y-damascone 203) and related compounds. ... 

N-Methylaniline in dry benzene added at 0° to ethylmagnesium bromide prepared from Mg and ethyl bromide in abs. ether, the resulting bromomagnesium N-methylanilide ice-cooled and treated with a soln. of the startg. methyl ketone in benzene, stirred 0.5 hr. at room temp., again ice-cooled, treated during 20 min. with acetaldehyde in benzene, and stirred 0.5 hr. y-damascone. Y 87%. F. Naf and R. Decorzant, Helv. 57, 1317 (1974). 

Fehr C (2006) Synthetic applications of enantioselective protonation and case study for (S)-a-damascone. In 45th Tutzing Symposiom Organocatalysis, Tutzing, Germany, 8-11 October 2006 Fujita K, Taguchi Y, Oishi A (2003) JP 3459986... 

Heating of this in the presence of base, to prevent elimination of the alcohol, gives the ketone via an ene reaction. The prefixes a-, (3- and y- have the same meaning in the damascone series as in the ionones. 

C13H20O, Mr 192.30, isomers of ionone which differ only in the position of the ring double bond (a-, /3-, Y-, S-, and c-damascone). The name damascones or rose ketones is derived from their occurrence in the essential oil of damask rose (Rosa damascena). a-D. bp. 77-80°C (0.13 Pa), [alg +487° (CHCI3) /5-D. bp. 52 °C (0.13 Pa). D. possess the common olfactory feature of a narcotic-herby odor of exotic flowers with an undertone resembling black currents. Although a- and /3-D. in rose oil have a combined content of merely ca. 0.15%, they determine the basic odor of the oil (olfactory threshold 0.009 ppb). D. occur in other flower oils as well as in tea, certain tobacco, and fruit aromas, e.g., apples and raspberries, a- and /3-D. are in-... 

Noma, Y, T. Etashimoto, and Y. Asakawa, 2001a. Microbiological transformation of damascone. Proc. 45th TEAC 93-95. 

Asakawa Y, Noma Y (2010) Biotransformation of sesquiterpenoids, ionones, damascones, adamantanes, and aromatic compounds by green algae, fungi, and mammals. In Baser KHC, Buchbauer G (eds) Handbook of essential oils. Science, technology, and applications. CRC Press, Boca Raton... 

An aq. soln. of NaHCOg added to a stirred soln. of / -ionone oxime (prepared from / -ionone, hydroxylamine hydrodiloride, and K-carbonate in water-ethanol) in tetrahydrofuran, protected from light, KI and iodine in water added, and refluxed 4 hrs. -> isoxazole deriv. (Y 91%) mixed with liq. NHg, tetrahydrofuran, and rerf-butanol, treated with Na until the soln. remains dark blue, stirred 15 min., and the crude / -aminoketone refluxed 24 hrs. with a trace of p-toluene-sulfonic acid in toluene / -damascone (Y 84%). F. e. s. G. Budii and J. C. Vederas, Am. Soc. 94, 9128 (1972) s. a. K. H. Sdiulte-Elte, B. L. Muller, and G. Ohloff, Helv. 56, 310 (1973). 

Scheme 1-7. Deracemization of methyl a-cyclogeranate (11) and a-damascone (12) by enolate protonation with (+)- and (-)-Y-isopropylephedrine.

Fehr C, Galindo J. Syntheses of the enantiomers of y-cyclo-geranic acid, -Y-cyclocitral, and a-damascone enantioselective protonation of enolates. Helv. Chim. Acta 1995 78 539-552. 

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