54973-16-9

Upstream product

• 5989-27-5 D-limonene 
• 203719-53-3 (-)-limonene oxide 
• 5989-54-8 (-)-(S)-limonene 
• 78-94-4 methyl vinyl ketone 
• 78-79-5 isoprene 
• 637033-15-9 (1S)-1-(2-hydroxy-2-methylpropanoyl)-4-methylcyclohex-3-ene 
• 185197-80-2 (4R)-4-acetyl-1,2-epoxy-1-methylcyclohexane 
• 917-54-4 methyllithium 
• 465500-08-7 (1R)-2-endo-[(1R)-4-methylcyclohex-3-en-1-ylcarbonyl]-1,7,7-trimethylbicyclo[2.2.1]heptan-2-ol 
• 4680-24-4 cis-(R)-limonene oxide 
• 174757-62-1 1-((1R,3S,4S)-4-Hydroxy-4-methyl-3-phenylselanyl-cyclohexyl)-ethanone 
• 1195-92-2 (4R)-limonene 1,2-epoxide 

Downstream Products

• 515-69-5 (+)-(1'R,6S)-α-Bisabolol 
• 70286-22-5 (R,Z)-methyl 3-(4-methyl-3-cyclohexenyl)-2-butenoate 
• 38142-44-8 (R,E)-methyl 3-(4-methyl-3-cyclohexenyl)-2-butenoate 
• 779358-25-7 Trifluoro-methanesulfonic acid 1-((R)-4-methyl-cyclohex-3-enyl)-vinyl ester 
• 515-69-5 α-bisabolol 
• 70286-23-6 (S,Z)-methyl 3-(4-methyl-3-cyclohexenyl)-2-butenoate 
• 70286-21-4 (S,E)-methyl 3-(4-methyl-3-cyclohexenyl)-2-butenoate 
• 70286-26-9 (S,Z)-3-(4-methyl-3-cyclohexnyl)-2-buten-1-ol 
• 70286-24-7 (S,E)-3-(4-methyl-3-cyclohexnyl)-2-buten-1-ol 

Relevant academic research and scientific papers

Viable route and DFT study for the synthesis of optically active limonaketone: A barely available natural feedstock in Cedrus atlantica

Herein, we report a novel, easy and efficient synthesis pathway of optically active limonaketone, a high added value monoterpene, starting from limonene, natural and low-cost feedstock. The strategy was developed in an excellent three-step total synthesis of limonaketone, potentially important intermediate in limonene ozonolysis and barely available in Cedrus atlantica essential oil (0.1% yield). The first step was the epoxidation of limonene which proceed in 91% yield. The ozonolysis of the prepared limonene oxide leads to the formation of the characteristic ketone function of limonaketone in 92% yield. The last step was performed by a deoxygenation in the presence of Zn and gave limonaketone in quantitative yield. The optically pure limonaketone has been efficiently synthesized from limonene and the overall yield was 84%. A molecular electron density theory (MEDT) analysis was carried out by using density functional theory (DFT) calculations at the M06–2X/6–311G(d,p) (LANL2DZ for Zn) level to understand the observed chemoselectivity in the Zn-deoxygenation reaction as well as its corresponding mechanistic pathway.

Flow Chemistry-Enabled Divergent and Enantioselective Total Syntheses of Massarinolin A, Purpurolides B, D, E, 2,3-Deoxypurpurolide C, and Structural Revision of Massarinolin A

Massarinolin A and purpurolides are bioactive bergamotane sesquiterpenes condensed with a variety of synthetically challenging ring systems: a bicyclo[3.1.1]heptane, an oxaspiro[3.4]octane, and a dioxaspiro[4.4]nonane (oxaspirolactone). Herein, we report the first enantioselective total syntheses of massarinolin A, purpurolides B, D, E, and 2,3-deoxypurpurolide C. Our synthesis and computational analysis also led to a structural revision of massarinolin A. The divergent approach features an enantioselective organocatalyzed Diels–Alder reaction to install the first stereogenic center in high ee, a scalable flow photochemical Wolff rearrangement to build the key bicyclo[3.1.1]heptane, a furan oxidative cyclization to form the oxaspirolactone, a late-stage allylic C?H oxidation, and a Myers’ NBSH-promoted sigmatropic elimination to install the exo methylene group of massarinolin A.

Enantioselective catalytic diels-alder reactions with enones as dienophiles

The aqua complexes (SM,RC)-[(η5-C 5Me5)M(PROPHOS)(H2O)][SbF6] 2 [PROPHOS = (R)-propane-1,2-diylbis(diphenylphosphane); M = Rh (1), Ir (2)] are active catalysts for the asymmetric Diels-Alder reaction between ketones and dienes. At low temperatures, enantioselectivities of up to 89% ee are achieved. The intermediate Lewis acid-dienophile complexes (S M,RC)-[(η5-C5Me 5)M(PROPHOS)(MVK)][SbF6]2 (MVK = methyl vinyl ketone; M = Rh (3), Ir (4)) and (SIr,RC)- [(η5-C5Me5)Ir(PROPHOS)(EVK)][SbF 6]2 (EVK = ethyl vinyl ketone (5)) have been isolated and characterized by analytical and spectroscopic means, including the determination of the crystal structure of the iridium complexes 4 and 5 by X-ray diffractometric methods. Structural parameters indicate that the dispositions of the coordinated dienophiles are controlled by the CH/π attractive interactions established between a phenyl group of the PROPHOS ligand and the α-vinyl proton of the ketones. Proton NMR parameters indicate that these interactions are maintained in solution. From these data, the stereoselectivity of the catalytic reaction is discussed.

(1R)-(+)-camphor and acetone derived α′-hydroxy enones in asymmetric diels-alder reaction: Catalytic activation by Lewis and bronsted acids, substrate scope, applications in syntheses, and mechanistic studies

Chemical Equation Presented The Diels-Alder reaction constitutes one of the most powerful and convergent C-C bond-forming transformations and continues to be the privileged route to access cyclohexene substructures, which are widespread within natural products and bioactive constituents. Over the recent years, asymmetric catalytic Diels-Alder methodologies have experienced a tremendous advance, but still inherently difficult diene-dienophile combinations prevail, such as those involving dienes less reactive than cyclopentadiene or dienophiles like β-substituted acrylates and equivalents. Here the main features of a'-hydroxy enones as reaction partners of the Diels-Alder reaction are shown, with especial focus on their potentials and limitations in solving the above difficult cases. α'-Hydroxy enones are able to bind reversibly to both Lewis acids and Bronsted acids, forming 1,4-coordinated species that are shown to efficiently engage in these inherently difficult Diels-Alder reactions. On these bases, a convenient control of the reaction stereocontrol can be achieved using a camphor-derived chiral α'-hydroxy enone model (substrate-controlled asymmetric induction) and either Lewis acid or Bronsted acid catalysis. Complementing this approach, highly enantio- and diastereoselective Diels-Alder reactions can also be carried out by using simple achiral α'-hydroxy enones in combination with Evans' chiral Cu(II)BOX complexes (catalyst-controlled asymmetric induction). Of importance, α'-hydroxy enones showed improved reactivity profiles and levels of stereoselectivity (endo/exo and facial selectivity) as compared with other prototypical dienophiles in the reactions involving dienes less reactive than cyclopentadiene. A rationale of some of these results is provided based on both kinetic experiments and quantum calculations. Thus, kinetic measurements of Bronsted acid promoted Diels-Alder reactions of α'-hydroxy enones show a first-order rate with respect to both enone and Bronsted acid promoter. Quantum calculations also support this trend and provide a rational explanation of the observed stereochemical outcome of the reactions. Finally, these fundamental studies are complemented with applications in natural products synthesis. More specifically, a nonracemic synthesis of (-)-nicolaioidesin C is described wherein a Brαnsted acid catalyzed Diels-Alder reaction involving a α'-hydroxy enone substrate is the key step toward the hitherto challenging tri substituted cyclohexene subunit.

Liquid-phase noncatalytic oxidation of monoterpenoids with nitrous oxide

A series of monoterpenoids differing in the number of double bonds and the pattern of their substitution were tested in the liquid-phase noncatalytic oxidation with nitrous oxide (N2O). The structure of olefins has a significant effect on the oxidation route. In the case of terpenoids containing 1,1-disubstituted double bond, nor-carbonyl compounds are formed with high selectivity.

Design and synthesis of endoperoxide antimalarial prodrug models

A masked combination chemotherapy which relies on the embedding of a number of active components, in a latent form, within a single endoperoxidic chemical entity is the aim of the research presented. The approach is illustrated by means of purposely designed bicyclic endoperoxide prodrug prototypes 1 and subsequently validated through the study of model compounds 2 (Ar= Ph, p-FC 6H4, p-ClC6H4.

α′-hydroxy Enones as Achiral Templates for Lewis Acid-Catalyzed Enantioselective Diels - Alder Reactions

α′-Hydroxy enones react with dienes in the presence of (S,S)-[Cu(tBu-box)](OTf)2 or (S,S)-[Cu(tBu-box)](SbF6)2 (2 to 10 mol %) to afford the corresponding Diels?Alder adducts in high yield and selectivity. Isomeric ratios (regioselectivity, endo/exo or cis/trans) of up to >99:1 and ee values of up to >99% are obtained. Significantly, difficult dienes such as isoprene, 2,3-dimethyl butadiene and piperylene behave satisfactorily. Subsequent oxidative cleavage of the ketol in the resulting cycloadducts by treatment with cerium ammonium nitrate (CAN) yields the corresponding enantiopure carboxylic acids. Alternatively, carbonyl addition and subsequent diol cleavage with CAN produces the corresponding ketone adducts. Copyright

A chiral acrylate equivalent for metal-free Diels-Alder reactions: endo-2-acryloylisoborneol

The principle of metal-free activation of enones toward the Diels-Alder reaction with dienes is demonstrated by exploiting the capability of Bronsted acids to activate α′-hydroxyenones through hydrogen bonding. The diastereoselective application of such a principle is nicely realized by using a newly designed family of camphor-based chiral enones, which upon catalytic action of either trifluoroacetic or triflic acid lead to the corresponding cycloadducts with high chemical and stereochemical efficiency. Copyright

Unexpected catalyzed C=C bond cleavage by molecular oxygen promoted by a thiyl radical

Olefin oxidation with molecular oxygen, promoted by a transition metal catalyst and a thiophenol, involved C=C bond cleavage into the corresponding carbonyl derivatives. This new reaction proceeds under one atmosphere of oxygen, at room temperature, in the presence of an excess of thiophenol and a catalyst such as MnL2 3a or VC1L2 3c. It was applied to aromatic and aliphatic olefins, as well as to functionalized or unfunctionalized acyclic compounds, providing the corresponding ketones and aldehydes in up to 98% yield. The synthetic interest of this catalytic oxidation was illustrated by a one-step preparation of the fragrance (-)-4-acetyl-1-methylcyclohexene 7e in 73% isolated yield. The C=C bond cleavage probably results from a catalyzed decomposition of the β-hydroperoxysulfide intermediate 12 that is formed by the radical addition of thiophenol to the olefin in the presence of oxygen. Although an excess of the thiophenol was used, it was transformed into the disulfide which could then be reduced without purification in 83% overall yield, thereby allowing for recycling. In addition, the C=C bond cleavage under oxygen could be promoted by catalytic quantities of the thiyl radical, generated by photolysis of the disulfide; thus, in the presence of 0.1 equiv of bis(4-chlorophenyl) disulfide 4b and 5% of the manganese complex 3a, trans-methylstilbene 1b gave, under radiation, benzaldehyde 6a and acetophenone 7a in up to 95% yield. This new reaction offers an alternative to the classical C=C bond cleavage procedures, and further developments in the fields of bioinorganic and environmental chemistry are likely.

Carboxylic acids in secondary aerosols from oxidation of cyclic monoterpenes by ozone

A series of smog chamber experiments have been conducted in which five cyclic monoterpenes were oxidized by ozone. The evolved secondary aerosol was analyzed by GC-MS and HPLC-MS for nonvolatile polar oxidation products with emphasis on the identification of carboxylic acids. Three classes of compounds were determined at concentration levels corresponding to low percentage molar yields: i.e. dicarboxylic acids, oxocarboxylic acids, and hydroxyketocarboxylic acids. Carboxylic acids are highly polar and have lower vapor pressures than their corresponding aldehydes and may thus play an important role in secondary organic aerosol formation processes. The most abundant carboxylic acids were the following: cis-pinic acid AB1 (cis-3- carboxy-2,2-dimethylcyclobutylethanoic acid) from α-and β-pinene; cis- pinonic acid A3 (cis-3-acetyl-2,2-dimethylcyclobutylethanoic acid) and cis- 10-hydroxypinonic acid AB6 (cis-2,2-dimethyl-3- hydroxyacetylcyclobutylethanoic acid) from α-pinene and β-pinene; cis-3- caric acid C1 (cis-2,2-dimethyl-1,3-cyclopropyldiethanoic acid), cis-3- caronic acid C3 (2,2-dimethyl-3-(2-oxopropyl)cyclopropanylethanoic acid), and cis-10-hydroxy-3-caronic acid C6 (cis-2,2-dimethyl-3-(hydroxy-2- oxopropyl)cyclopropanylethanoic acid) from 3-carene; cis-sabinic acid S1 (cis-2-carboxy-1-isopropylcyclopropylethanoic acid) from sabinene; limonic acid L1 (3-isopropenylhexanedioic acid), limononic acid L3 (3-isopropenyl-6- oxo-heptanoic acid), 7-hydroxylimononic acid L6 (3-isopropenyl-7-hydroxy-6- oxoheptanoic acid), and 7-hydroxylimononic acid L6' (7-hydroxy-3-isopropenyl- 6-oxoheptanoic acid) from limonene. A series of smog chamber experiments have been conducted in which five cyclic monoterpenes were oxidized by ozone. The evolved secondary aerosol was analyzed by GC-MS and HPLC-MS for nonvolatile polar oxidation products with emphasis on the identification of carboxylic acids. Three classes of compounds were determined at concentration levels corresponding to low percentage molar yields: i.e. dicarboxylic acids, oxocarboxylic acids, and hydroxyketocarboxylic acids. Carboxylic acids are highly polar and have lower vapor pressures than their corresponding aldehydes and may thus play an important role in secondary organic aerosol formation processes. The most abundant carboxylic acids were the following: cis-pinic acid AB1 (cis-3-carboxy-2,2-dimethylcyclobutylethanoic acid) from α- and β-pinene; cis-pinonic acid A3 (cis-3-acetyl-2,2-dimethylcyclobutylethanoic acid) and cis-10-hydroxypinonic acid AB6 (cis-2,2-dimethyl-3-hydroxyacetylcyclobutyl-ethanoic acid) from α-pinene and β-pinene; cis-3-caric acid C1 (cis-2,2-dimethyl-1,3-cyclopropyldiethanoic acid), cis-3-caronic acid C3 (2,2-dimethyl-3-(2-oxopropyl)cyclopropanylethanoic acid), and cis-10-hydroxy-3-caronic acid C6 (cis-2,2-dimethyl-3-(hydroxy-2-oxopropyl)cyclopropanyl-ethanoic acid) from 3-carene; cis-sabinic acid S1 (cis-2-carboxy-1-isopropylcyclopropylethanoic acid) from sabinene; limonic acid L1 (3-isopropenylhexanedioic acid), limononic acid L3 (3-isopropenyl-6-oxo-heptanoic acid), 7-hydroxy-limononic acid L6 (3-isopropenyl-7-hydroxy-6-oxoheptanoic acid), and 7-hydroxylimononic acid L6′ (7-hydroxy-3-isopropenyl-6-oxoheptanoic acid) from limonene.