Artemisia-ketone

A mixture of senecioyl chloride (0.1 mol) and A1C13 (0.1 mol) in dichloromethane (50 ml) was added dropwise over 45 min with stirring to a solution of dimethylallyltrimethylsilane (O.llmol) in dichloromethane (KK)ml), previously cooled to — 60 °C. The reaction mixture was maintained at this temperature for 10 min after the final addition, and then poured slowly onto a mixture of crushed ice and ammonium chloride. After washing of the organic layer with brine and drying, artemisia ketone (0.09 mol, 90%). b.p. 87°C/200mmHg, was obtained. 

Aminosilanes, 87-9 Artemisia ketone, 33 Aryl silyl ethers, 41 Arylsilanes, 39-43 Arylsulphonylhydrazones, 12 Aryltrimethylsilanes, 39, 42,43 Azetidin-2-ones, 70 Azetidin-2-one 4-carboxylic acids, 92... 

Monoaddition to esters. The reagent formed from RMgX and LDA (1 1) reacts with esters or amides to give enolates of ketones, which can be trapped by ClSi(CH,)v This technique provides a synthesis of artemisia ketone (1) by an aldol... 

Artemisia ketone (2) Artemisinic alcohol (3) Arteannuin B (4) 1,8-Cineole (5) Camphor (6) Fig. 2. Examples of some secondary metabolites isolated from Artemisia annua. 

The other major group of irregular monoterpenes is formed by non-head-to-tail fusion of isoprene units. Important members include artemisia ketone 64, santolinatriene 65, chrysanthemol 66, yomogi alcohol 67 and lavandulol 68 (Structure 4.15). Lavandulane-type compounds occur in the families Lamiaceae (Labiatae) and Apiaceae (Umbelliferae), while chrysanthemane, artemisane and santolinane types occur in the family Asteraceae (Compositae) [47,48]. 

Roman mugwort Artemisia pontica L. Artemisia ketone (23-46), a-thu-jone (14-30), 1,8-cineole (12-23)... 

How could the same route also lead to the natural products yomogi alcohol and artemisia ketone ... 

The analysis of essential oils which contain monoterpenoids has contributed many papers to the literature this year a disturbing number of analyses are trivial and furnish little that is new. The validity of the natural occurrence of minor components can be questioned in the light of isolation technique linalyl acetate yields eleven monoterpenoids on steam distillation.87 Analyses of interest are the major component (58%) of the steam-volatile leaf oil of Zieria aspalathoides is (—)-car-3-en-2-one 88 (+)-2,6-dimethyloct-7-en-4-one is the major component (97%) in Phebalium glandulosum subsp. glandulosum 89 major components in Achillea millefolium essential oil (isolated by steam distillation ) are sabinene and artemisia ketone,90 which is incorrectly named by the authors as isoartemisia ketone (possibly from... 

Essential oil from A. annua is another active research interest as it could be potentially used in perfume, cosmetics, and aromatherapy. Depending on its geographical origin, the oil yield in A. annua ranges from 0.02% to 0.49% on a fresh weight basis and from 0.04% to 1.9% on a dry weight basis. The major components in the oil were reported to be artemisia ketone (80), isoartemisia ketone (81), 1,8-cineole (82), and camphor (83) (Structure 5-5). GC/MS was employed to analyze the chemical composition in the essential oil more than 70 constituents have been identified. For more detailed information on the oil composition of essential oil from A. annua, the readers are referred to Refs. 65, 66 and 72-81. 

Takemoto, T. Nakajima, T. Study on the essential oil of Artemisia annua L. III. Discussion on the stmcture of artemisia ketone, ibid 1339-1344. 

Karamenderes et al. [67] reported the composition and antimicrobial activity of the essential oils obtained from Achillea millefolium L. subsp. pannonica (Scheele) Hayek, Achillea millefolium subsp. millefolium, Achillea arithmifolia Waldst Kitt and Achillea kotschyi Boiss. subsp. kotschyi, four Achillea species from Turkey. 1,8-cineole, Fig. (2), artemisia alcohol and ascaridole were identified as major components. The essential oils showed antibacterial and antifungal effects even with low concentrations. The essential oil of the flowering tops of another Achillea species, Achillea fragantissimum (Forsk.) Sch. Bip growing in Sinai, was analyzed [68]. Santolina alcohol, a- and P-thujone, Fig. (5) and artemisia ketone account for approximately 80% of the oil. The oil showed marked antimicrobial activities against Escherichia coli. Bacillus subtilis and Staphylococcus aureus. 

The efficient addition of allylic bromides to carbonyl compounds in a heated zinc column has been used to synthesize ( )-artemisia alcohol (81 R = H, X = CH2) in 91% yield.Artemisia ketone was synthesized efficiently from 3-methyl-l-trimethylsilylbut-2-ene and 3-methylbut-2-enoyl chloride in the presence of AlCls. Racemic methyl santolinate (82) was synthesized (along with the C-3 epimer ratio 8 1) via Claisen rearrangement, according to Scheme 2 (cf. Vol. 6, p. 7). ... 

Little is known of the biosynthetic routes to the irregular monoterpenoids. It has been suggested that chrysanthemyl alcohol is a parent of the class that includes artemisia ketone, lavandulol, and santolinatriene, and stereochemical considerations have indicated that the (1/ , 3i )-isomer (16) of this alcohol would be the required precursor. The alcohol (16) occurs in Artemisia ludoviciana, and this is the first identification of the alcohol from a natural source. The santolinyl compound (17) also occurs in Artemisia tridentata and the 5-stereochemistry at C-3 is as expected if (16) (presumably as its pyrophosphate ester) is a precursor. 

New naturally occurring monoterpenes having the artemisia skeleton include artemisia ketone epoxide (208), isolated from Artemisia vulgaris and synthesized from prenyl chloride (15, R = Cl), and senecioic acid (59) chloride under Grignard conditions.( + )-Artemisia alcohol (209) has been isolated from A. herba alba [the usually encountered form is the (- )-(S)-isomer (- )-209]. An incompletely characterized triacetate 210 is also reported from the Brazilian plant Calea oxylepis. ... 

Additions to enones, e.g. 115 generally occur in the Michael sense giving 8,e-unsaturated enones33 such as 116. Acetals 118 can replace aldehydes in additions with allylic transposition34 as in 117 to 119 and acylation occurs with acid chlorides as in the synthesis of the terpene artemisia ketone 122 from two C5 units with at least a passing resemblance to the biosynthesis of this irregular terpene.20,35... 

Essential oil composition studies of interest concern Mentha rotundifolia [—85% piperitenone epoxide (26)], Artemisia afra (cineole, artemisia ketone. 

Further papers on new chemotypes include reports of two chemotypes of Achillea ageratum (one high in artemisia ketone and artemisyl acetate content... 

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