Search

Monoterpenoids are a large group of natural, speciality chemicals. Their global demand is surging and the use of engineered microbial hosts such as Escherichia coli is a compelling strategy to sustainably and economically produce these molecules at scale. However, most monoterpenoids are highly volatile, which presents unique challenges for their recovery. The use of biphasic fermentations employing a dodecane overlay for product capture has emerged as a popular solution to this problem. However, since the subsequent separation of the products from dodecane is exceptionally difficult, biphasic fermentations are not practical. To this end, we report the development of an extraction methodology employing a fluidized bed of an aliphatic methacrylate resin for ex situ recovery of carene that is produced by a genetically engineered strain of E. coli. The resin is suspended in water within a 3D‐printed reservoir and volatilized carene is continuously captured by sparging the gaseous outflow from the condenser of the fermenter through the reservoir. We observed that the adsorption of carene onto the resin follows the Freundlich equation and that the extraction efficiency was chiefly influenced by the rate of agitation of the fermentation broth, the volume of resin enclosed within the reservoir, and the airflow rate into the fermenter. We subsequently used a fractional factorial experimental design to identify optimal levels of each parameter and thereafter improved the extraction efficiency six‐fold over that of a dodecane overlay. Our work establishes strong foundations for the use of solid phase‐transfer separations for the continuous recovery of volatile fermentation products. [ABSTRACT FROM AUTHOR]

[Display omitted] Reaction of trans -4-hydroxymethyl-2-carene with thiophene- 2-carbaldehyde under heterogeneous catalysis by K10 clay affordsubstitutedmethanopyrano[4,3- b ]thieno[3,2- g ]- benzofuran, a complex 5-membered chiral cage heterocyclic compound containing two thiophene moieties. Its structure was determined by 1D and 2D NMR experiments (HSQC, HMBC, COSY, NOESY) and HRMS. [ABSTRACT FROM AUTHOR]

Three‐component condensation of aldehydes and dimethyl phosphite with α‐amino oximes derived from (−)‐α‐pinene and (+)‐3‐carene (Kabachnik‐Fields reaction) resulted in amino phosphonates as pairs of diastereomers. Diastereomeric ratio depends on the catalyst used (SnCl2×2H2O, SiO2, Al2O3‐H+) and the heating type (conventional or microwave). The best results were achieved by MW irradiation with simultaneous cooling. Stereochemical assignment of the key derivatives was made by X‐ray diffractometry. According to quantum chemical calculations (DFT PBE0/def2‐TZVPP) and spectroscopic data, the terpenic α‐amino phosphonates should be conformationally inhomogeneous, exhibiting a tendency to form H‐bonded dimers (DFT M06/def2‐SVP, IR). One‐bond spin‐spin coupling 1JP–C was found to be diagnostic for the configuration assignment since the value 1JP–C depends on the dihedral angle between bond C−P and axis of the electron lone pair at the neighboring nitrogen (NMR, DFT PBE0/aug‐cc‐pVTZ−J). [ABSTRACT FROM AUTHOR]

• First comprehensive study of the catalytic condensation of renewable 3-carene with formaldehyde. • The resulting terpenoid 4-hydroxymethyl-2-carene as a fragrant compound and a chiral platform. • Selectivity to the target product is limited by its further transformations (acetylation and formaldehyde addition). • Phosphoric acid as the most selective catalyst (up to 67%). • The mechanism and pathways were discussed based on experimental work, DFT calculations and kinetics modeling. This work is a first comprehensive study of the catalytic condensation of renewable 3-carene with formaldehyde (FA) for the one-step preparation of terpenoid trans -4-hydroxymethyl-2-carene, a commercially significant fragrance and a chiral platform chemical. Commonly available Brønsted and Lewis acids, as well as aluminosilicates (halloysite nanotubes, K-10 montmorillonite, H-Beta-25 zeolite) are able to catalyze the reaction in acetic acid, however, selectivity to the desired product is limited due to further transformations by (i) acetylation and (ii) addition of a second FA molecule. Compounds of successive condensation with FA are mainly formed in the presence of ZnCl 2 and LiClO 4 , giving up to 50 % yield, while weak to moderate acidic halloysite and K-10 (45–104 µmol/g) result in a low conversion of 3-carene with a prevalence of acetylation products (up to 46 %). The largest selectivity towards trans -4-hydroxymethyl-2-carene at substrate conversion of 50 % was observed with phosphoric acid (50–66 %). The yield of the desired terpenoid increased significantly with an excess of FA or the catalyst loading, because the amount of the active form of formaldehyde is the key factor in the reaction. Presence of water in the system also led to a certain selectivity increase explained by inhibition of the side reaction. Under optimized conditions using H 3 PO 4 -AcOH mixture as a catalyst at 15 °C, selectivity to the target product was ca. 67 %. A detailed mechanism for the 3-carene condensation with FA has been proposed. The DFT calculations show that further transformations of trans -4-hydroxymethyl-2-carene are energetically favorable in agreement with the experimental data The reaction pathways were also confirmed by kinetic modeling. Synthesis of the desired product was performed on a scale up to 25 g and a possibility of 3-carene recycling has been demonstrated. [Display omitted] [ABSTRACT FROM AUTHOR]

Two novel structural types of tyrosyl-DNA phosphodiesterase 1 (TDP1) inhibitors with hexahydroisobenzofuran 11 and 3-oxabicyclo [3.3.1]nonane 12 scaffolds were discovered. These monoterpene-derived compounds were synthesized through preliminary isomerization of (+)-3-carene to (+)-2-carene followed by reaction with heteroaromatic aldehydes. All the compounds inhibit the TDP1 enzyme at micro- and submicromolar levels, with the most potent compound having an IC50 value of 0.65 μM. TDP1 is an important DNA repair enzyme and a promising target for the development of new chemosensitizing agents. A panel of isogenic clones of the HEK293FT cell line knockout for the TDP1 gene was created using the CRISPR-Cas9 system. Cytotoxic effects of topotecan (Tpc) and non-cytotoxic compounds of the new structures were investigated separately and jointly in the TDP1 gene knockout cells. For two TDP1 inhibitors, 11h and 12k, a synergistic effect was observed with Tpc in the HEK293FT cells but was not found in TDP1 −/− cells. Thus, it is likely that the synergistic effect is caused by inhibition of TDP1. Synergy was also found for 11h in other cancer cell lines. Thus, sensitizing cancer cells using a non-cytotoxic drug can enhance the efficacy of currently used pharmaceuticals and, concomitantly, reduce toxic side effects.

New chiral 1,10-phenanthroline-derived ligands containing fragments of (+)-3-carene (L1) and (+)-limonene (L2) natural monoterpenoids and their complexes Zn(L1,2)Cl2·1.5H2O, Cd(L1,2)Cl2·nH2O, Zn(L1)Br2·2H2O, and Cd(L1)Br2·2H2O were synthesized. According to NMR and IR spectroscopy data, a conclusion was made about the polynuclear structure of the compounds obtained. Luminescent properties of the compounds obtained were investigated. Lifetimes of the excited states and luminescence quantum yields (φf) were determined. For free ligands, blue fluorescence was observed. In the case of Zn(II) and Cd(II) complexes, luminescence appeared in the green region of the spectrum. [ABSTRACT FROM AUTHOR]

Highlights • δ-3-Carene; a safety assessment based on RIFM's criteria. • A safety assessment based on 7 human health endpoints plus environmental. • All endpoints were cleared using target data, read-across, and/or TTC. [ABSTRACT FROM AUTHOR]

[Display omitted] • Commercial montmorillonite K-30 as a catalyst for 3-carene isomerization to 2-carene. • Increase of 2-carene yield with a decrease in the Lewis to Brønsted acid sites ratio. • Commercial K-10 clay as a catalyst of synthesis of chiral isobenzofurans from 2-carene containing reaction mixture. • Increase of the isobenzofurans yield using the 2-carene containing mixture as compared to 2-carene per se. Isomerization of 3-carene to the reaction mixture, containing 2-carene and its further utilization in the synthesis of chiral isobenzofurans, was investigated in the presence of acid-modified clays at 140 °C. The catalysts were characterized by XRF, FTIR with pyridine and nitrogen adsorption. Quantification of the effect of the type and concentration of acid sites in different clays comprising commercial montmorillonite and natural illite on the yield of 2-carene as well as by-products was obtained for the first time. It was established that selectivity to 2-carene decreased with an increase of the Lewis to Brønsted acid sites ratio. The largest amount of 2-carene in the mixture (15.0 wt.%) with the highest ratio of 2-carene to menthadienes (0.63) was observed at 50% 3-carene conversion over a commercial montmorillonite K-30 clay, which has a moderate (100 μmol/g) acidity. It was demonstrated for the first time that the mixture containing 2-carene can be effectively used as a starting material in the reaction with vanillin resulting in chiral isobenzofurans. The products obtained in this reaction exhibit neuroprotective activity in an animal Parkinson's disease model. It was established that isobenzofurans yield decreased with an increase in the Lewis to Brønsted acid sites ratio. The largest yield of these products was obtained in the presence of a commercial K-10 clay (59.8%), which is higher than using 2-carene per se. Catalytic synthesis of isobenzofurans based on a readily available monoterpene 3-carene instead of expensive 2-carene was thus developed. [ABSTRACT FROM AUTHOR]

Abstract This study investigated the reduction of terpene emissions from Oriented Strand Boards (OSB) by pre-treatment of pine wood strands with a mixed culture of Pseudomonas bacteria and the ascomycete Penicillium nigricans. While Pseudomonas alone efficiently degraded α-pinene and β-pinene, the combined action of both microorganisms was required for the simultaneous degradation of all three major terpenes in pine wood including Δ3-carene. Δ3-carene emissions from laboratory OSB were 60% and 35% lower than that of controls after 4 and 2 days of microbial pre-treatment, respectively. At the same time, α-pinene emissions were reduced by 85% and 45%, while β-pinene emissions were completely absent. Δ3-carene degradation was no longer observed at a short-term treatment of only 1 day. However, laccase in the presence of a redox mediator may overcome this limitation by oxidation of Δ3-carene to non-volatile carenones. The results revealed the potential of biotechnology for reducing potentially harmful terpene emissions from wood products. Highlights • Oriented Strand Boards with greatly reduced terpene emission levels were produced. • Combined action of Pseudomonas and Penicillium reduces all terpenes in pine wood. • Laccase-mediator system oxidises volatile Δ3-carene to non-volatile carenones. • Microbial treatment time reduced to 24–48 h meeting industrial requirements. [ABSTRACT FROM AUTHOR]

Complexes [CuL¹Cl2] (I), [CuL²Cl2] · EtOH (II), and Cu2L3Cl4 (III) containing esters of the N-derivatives of optically active amino acids based on (+)-3-carene (L¹, L²) and (–)-α-pinene (L³) are synthesized. The crystal and molecular structures of compounds I and II are determined by X-ray diffraction analyses (CIF files CCDC nos. 1560071 (I), 1560072 (II)). The crystal structure of compound I consists of mononuclear complex molecules. In the structure of compound II, the unit cell contains two crystallographically independent molecules of mononuclear complex [CuL²Cl2] and two EtOH molecules. Ligands L¹ and L² perform the tridentate-chelating function by the N atoms of the NH and NOH groups and by the O atom of the C=O group. In compounds I and II, the coordination polyhedra Cl2N2O of the Cu atoms are trigonal bipyramid. According to the data of IR and electronic spectroscopy, binuclear complex III has similar coordination polyhedra. The experimental values of μeff for compounds I, II, and III at 300 K are 1.93, 1.88, and 2.71 μB. For complex III, the μeff(T) dependence in a range of 2-300 K indicates a weak ferromagnetic exchange interaction. [ABSTRACT FROM AUTHOR]

Stereoselective synthesis of monoterpene-based 1,2,4- and 1,3,4-oxadiazole derivatives was accomplished starting from α,β-unsaturated carboxylic acids, obtained by the oxidation of (--)-2-carene-3-aldehyde and commercially available (--)-myrtenal. 1,2,4-Oxadiazoles were prepared in two steps via the corresponding O-acylamidoxime intermediates, which then underwent cyclisation induced by tetrabutylammonium fluoride (TBAF) under mild reaction conditions. Stereoselective dihydroxylation in highly stereospecific reactions with the OsO4/NMO (N-methylmorpholine N-oxide) system produced α,β-dihydroxy 1,2,4-oxadiazoles. Pinane-based 1,3,4-oxadiazoles were obtained similarly from acids by coupling with acyl hydrazines followed by POCl3-mediated dehydrative ring closure. In the case of the arane counterpart, the rearrangement of the constrained carane system occurred with the loss of chirality under the same conditions. Stereoselective dihydroxylation with OsO4/NMO produced α,β-dihydroxy 1,3,4-oxadiazoles. The prepared diols were applied as chiral catalysts in the enantioselective addition of diethylzinc to aldehydes. All compounds were screened in vitro for their antiproliferative effects against four malignant human adherent cell lines by means of the MTT assay with the O-acylated amidoxime intermediates exerting remarkable antiproliferative action. [ABSTRACT FROM AUTHOR]

Dastarcus helophoroides Fairmaire (Coleoptera: Bothrideridae) is an effective predatory beetle of larvae and pupae of several cerambycid beetles including Monochamus alternatus and Anoplophora glabripennis. Electroantennography (EAG) and a dynamic two-choice olfactometer were respectively used to measure the antennal and behavioral responses of both sexes to selected volatile compounds. Female and male D. helophoroides exhibited similar EAG and behavioral responses. Significant dose-dependent EAG responses in both sexes were elicited by nonanal, octanal, cis-3-hexenol, 3-carene, (R)-(+)-α-pinene, (S)-(-)-α-pinene, (R)-(+)-limonene and (S)-(-)-limonene. Female and male beetles were repelled at high concentration by cis-3-hexenol and (S)-(-)-limonene, respectively. Both sexes of D. helophoroides were significantly attracted to nonanal, cis-3-hexenol, 3-carene and (R)-(+)-limonene even at low concentrations. These compounds might be used either individually or in mixtures for developing biological control methods to attract this predatory beetle into forest stands threatened by cerambycid beetles. [ABSTRACT FROM AUTHOR]

[Display omitted] • Modified clays as effective catalysts for isomerization of α-pinene to camphene. • Increase of selectivity to camphene with a decrease of catalyst acidity. • Higher selectivity to mentadienes on clays compared to other catalysts. • Formation of extremely valuable 2-carene from 3-carene in presence of acid aluminosilicates. • Kinetic modelling of 3-carene transformation. The catalytic properties of acid-modified montmorillonite, kaolinite (Mongolia) and illite (Belarus) clays, as well as a commercial aluminosilicate catalyst AS-36 were studied in the liquid-phase isomerization of α-pinene and 3-carene. The largest conversion of α-pinene (100% after 6 h) was observed in the presence of illite clay treated with 10% HCl at 90 °C. The presence of only weak and medium acidic sites in the clays resulted in the formation of camphene (50.1–54.3%) as the main reaction product. Conversion of 3-carene increases with an increase of the total catalyst acidity. The reaction products were 2-carene (11.9–15.0%), mentadienes (35.5–48.5%), menthenes (7.9–17.1%) and cymenes (10,1–20.4%). The amount of mentadienes in the reaction mixture decreased while the opposite was observed for menthenes and cymenes with increase of concentration and strength of the acid sites. The kinetic model for 3-carene transformations was developed. [ABSTRACT FROM AUTHOR]

A simple five-step process for the conversion of technical grade (+)-3-carene into 6,6-dimethylbicyclo[3.1.0]hexan-3-one was developed. A robust process was required that delivered the 6,6-dimethylbicyclo[3.1.0]hexan-3-one, minimized chromatography, reduced the excess of silver salts, and avoided toxic chromium oxidants. A simple and scalable process that relies on crystallization and distillation was developed and demonstrated to produce hundreds of grams of 6,6-dimethylbicyclo[3.1.0]hexan-3-one. [ABSTRACT FROM AUTHOR]

Tosylhydrazide was shown to be an effective reductant in protic solvents for the peroxide ozonolysis products of ∆-carene, (-)- α-pinene, and ( S)-limonene. Either α, ω-ditosylhydrazones or α, ω-ketotosylhydrazonoacids were formed depending on the nature of the trisubstituted cycloalkene. [ABSTRACT FROM AUTHOR]

Leptoglossus occidentalis causes significant damage in conifer seed orchards. Host selection by L. occidentalis is not completely understood. Earlier research has demonstrated a preference for certain clones of Pinus contorta, indicating that L. occidentalis responds to chemical or physical cues., The present study aimed to test whether L. occidentalis shows clonal preference across years, and to examine whether the host cues responsible for this could be identified., Surveys were conducted in a lodgepole pine seed orchard in British Columbia in 2008 and 2009. Clones were ranked based on the proportion of their ramets on which L. occidentalis was observed. Ramets were divided into three classes: (i) preferred clones with seed bugs; (ii) preferred clones without seed bugs; and (iii) nonpreferred clones with zero or very low numbers of seed bugs. From each clone, we measured infrared radiation emitted from cones, cone monoterpenes, cone size and numbers of cones per tree., Clone preference was consistent between 2008 and 2009. Clone preference classes differed significantly in α-pinene and δ-3 carene and limonene., Leptoglossus occidentalis was found more frequently on clones with cones of greater diameter and weight., Infrared radiation did not differ between clone preference classes, indicating that it is not used in host acceptance. [ABSTRACT FROM AUTHOR]

Five monoterpenoids were isolated from the endophytic fungusPericoniasp. F-31, including three new carene-type monoterpenoids, 2-carene-5,8-diol (1), 2-carene-8,10-diol (2), 2-carene-8-acetamide (3), one new menthene-type monoterpenoid 8-hydroxy-1,7-expoxy-2-menthene (4), and one known monoterpenoid anethofuran (5). The structures of all compounds were elucidated based on a comprehensive spectroscopic data analysis, electronic circular dichroism (ECD), and calculated ECD. [ABSTRACT FROM PUBLISHER]

Biotransformation of (1S)-2-carene and (1S)-3-carene by Picea abies suspension culture led to the formation of oxygenated products. (1S)-2-Carene was transformed slowly and the final product was identified as (1S)-2-caren-4-one. On the other hand, the transformation of (1S)-3-carene was rapid and finally led to the formation of (1S)-3-caren-5-one and (1S)-2-caren-4-one as equally abundant major products. The time-course of the reaction indicates that some products abundant at the beginning of the reaction (e.g. (1S,3S,4R)-3,4-epoxycarane and (1R)-p-mentha-1(7),2-dien-8-ol) were consumed by a subsequent transformations. Thus, a precise selection of the biotransformation time may be used for a production of specific compounds.

The qualitative and quantitative compositions of isomerization products of 3-carene over acid-treated glauconite were established using NMR and GC methods. Chemical shifts of H and C nuclei of identified compounds were assigned. A possible mechanism of the isomerization transformations was proposed. [ABSTRACT FROM AUTHOR]

The addition of perfluoroalkanoic acids to 3-carene involves opening of the cyclopropane ring at the peripheral bonds with formation of a mixture of isomeric p-menth-1-en-8-yl and m-menth-1-en-8-yl perfluoroalkanoates. The reaction rate decreases as the length of the perfluoroalkyl radical of the acid increases. Trichloroacetic acid reacted with 3-carene at a lower rate than does trifluoroacetic acid, but the products are analogous p-menth-1-en-8-yl and m-menth-1-en-8-yl trichloroacetates. [ABSTRACT FROM AUTHOR]

The exacting technology of piezoelectric aroma sensor has engendered a great hope for determining the ripening aroma of mango ( Mangifera indica L.). 3-Carene is one of the most important ripeness indicating aromas of mango. Detection of 3-Carene content in mango is very important because fruit aroma and flavor characteristics are of key importance in determining consumer acceptance in commercial fruit markets. quartz crystal microbalance (QCM) transduces changes in mass on the crystal surface into measurable shifts in resonant frequency due to its sensitive solution-surface interface measurement capability. In this exploration, poly-dimethylsiloxane (PDMS) coated QCM sensor has been developed to sense the aroma of 3-Carene volatile in Indian mango varieties namely Langda and Chausa cultivars of mango. Empirically the performance of the sensor has been validated by characterizing the sensor through different studies viz. sensitivity, selectivity, repeatability, reproducibility, period of reusability, etc. The sensor was found to be selective to 3-Carene mostly, unlike other dominant aromas present in mango. Validation of the proposed sensor with real mangoes are carried out by correlating the frequency deviation of the sensor with the estimations of 3-Carene obtained from gas chromatography mass spectrometry (GC–MS). [ABSTRACT FROM AUTHOR]

Thermal decomposition studies of 3-carene, a bio-fuel, have been carried out behind the reflected shock wave in a single pulse shock tube for temperature ranging from 920 K to 1220 K. The observed products in thermal decomposition of 3-carene are acetylene, allene, butadiene, isoprene, cyclopentadiene, hexatriene, benzene, toluene and p-xylene. The overall rate constant for 3-carene decomposition was found to be Ab-initio theoretical calculations were carried out to find the minimum energy pathway that could explain the formation of the observed products in the thermal decomposition experiments. These calculations were carried out at B3LYP/6-311 + G(d,p) and G3 level of theories. A kinetic mechanism explaining the observed products in the thermal decomposition experiments has been derived. It is concluded that the linear hydrocarbons are the primary products in the pyrolysis of 3-carene. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

The preparation of some chiral cyclic synthetic intermediates from car-3-ene, linalool, limonene, α-pinene and camphor, is reviewed. Some applications of these intermediates are described. [ABSTRACT FROM AUTHOR]

The effect of NO2 on secondary organic aerosol (SOA) formation from ozonolysis of α-pinene, β-pinene, Δ3carene, and limonene was investigated using a dark flowthrough reaction chamber. SOA mass yields were calculated for each monoterpene from ozonolysis with varying NO2 concentrations. Kinetics modeling of the first-generation gasphase chemistry suggests that differences in observed aerosol yields for different NO2 concentrations are consistent with NO3 formation and subsequent competition between O3 and NO3 to oxidize each monoterpene. α-Pinene was the only monoterpene studied that showed a systematic decrease in both aerosol number concentration and mass concentration with increasing [NO2]. β-Pinene and Δ3carene produced fewer particles at higher [NO2], but both retained moderate mass yields. Limonene exhibited both higher number concentrations and greater mass concentrations at higher [NO2]. SOA from each experiment was collected and analyzed by HPLC-ESI-MS, enabling comparisons between product distributions for each system. In general, the systems influenced by NO3 oxidation contained more high molecular weight products (MW>400 amu), suggesting the importance of oligomerization mechanisms in NO3-initiated SOA formation. α-Pinene, which showed anomalously low aerosol mass yields in the presence of NO2, showed no increase in these oligomer peaks, suggesting that lack of oligomer formation is a likely cause of α-pinene's near 0 % yields with NO3. Through direct comparisons of mixed-oxidant systems, this work suggests that NO3 is likely to dominate nighttime oxidation pathways in most regions with both biogenic and anthropogenic influences. Therefore, accurately constraining SOA yields from NO3 oxidation, which vary substantially with the volatile organic compound precursor, is essential in predicting nighttime aerosol production. [ABSTRACT FROM AUTHOR]

Ignition delay experiments of 3-carene, a biofuel, have been carried out in a single-pulse shock tube for three equivalence ratios, 0.5, 1 and 2. The temperature was varied from 1140 to 1606 K. In the above-mentioned conditions, ignition delay was found to vary from 1.180 ms to 144 μs. The ignition delay values of 3-carene were found to be lower than those of JP-10, a kerosene-based fuel being considered for hypersonic applications. [ABSTRACT FROM AUTHOR]

The article presents theoretical calculations about the reaction of (+)-2-carene with ozone. Topics discussed include quantum chemical calculations using density functional theory, the mechanism of ozonolysis of sesquiterpenes and terpenes, and the formation of carboxylic acids and ester compounds during the oxidation of 2-carene by ozone.

A simple and efficient method for synthesizing chiral heterocyclic compounds with the hexahydrofluoreno[9,1- bc ]furan framework via interaction between trans -4-hydroxymethyl-2-carene and aromatic aldehydes containing methoxy and hydroxyl moieties in the presence of montmorillonite clay was found. One of the synthesized compounds exhibited a high cytotoxic activity against lymphoblastoid cell line MT-4 (CTD 50 0.9 μM), which was higher than that of the comparative drug Doxorubicin. Death of cancer cells in this case substantially occurs via induction of apoptosis. [ABSTRACT FROM AUTHOR]

Optically active isoniazid derivatives containing a cyclopropane or cyclobutane fragment have been synthesized by ozonolysis of (+)-Δ³-carene and (-)-α-pinene, followed by treatment of the ozonolysis products with isonicotinic acid hydrazide. [ABSTRACT FROM AUTHOR]

A simple synthetic procedure for the preparation of mono-N-tosylated-1,2-diamines derived from (+)-3-carene is described. (+)-3-Carene is transformed into the corresponding N-tosylaziridine derivative using chloramine-T trihydrate. Subsequent ring opening with sodium azide followed by reduction of the azide function gives the optically pure mono-N-tosylated-1,2-diamine. This ligand is effective in asymmetric transfer hydrogenations of aromatic ketones. It can also be transformed into other chiral ligands by alkylation of the amino group for application in the addition of diethylzinc to benzaldehydes [ABSTRACT FROM AUTHOR]

The rate coefficients for the reactions of ozone with 2-carene and 3-carene have been measured at 760 Torr of air and 299 ± 6 K using both absolute and relative methods. The data obtained are (in units of ×10 −17 cm 3 molecule −1 s −1 ): k (2-carene) = 23.8 ± 1.0, k (3-carene) = 3.7 ± 0.2. The present work supplements the kinetic database of 2-carene and 3-carene using varied conventional experimental methods. The results are compared with the literature data and discussed with respect to atmospheric chemistry. [ABSTRACT FROM AUTHOR]

ABSTRACT This work presents odour characteristics of a newly synthesized family of seven terpenoid alcohols with citrusy grapefruit odours. The alcohols were prepared from citronellal that was subjected to a two- or three-step reaction sequence to deliver secondary or tertiary alcohols. Two other compounds with an acetal structure (containing 18 and 19 carbon atoms) with the same odour type and very high tenacity were synthesized from (+)-3-carene. The most olfactorily potent compounds were 5,9-dimethyldec-8-en-2-ol 10 and 2-carene derivative acetal 25. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The mechanisms for the photochemical isomerization reactions are investigated theoretically using a model system of (+)-2-carene-4α-methanol (2-carene) 1, using the CASSCF (eight-electron/six-orbital active space) and MP2-CAS methods and the 6-311( d) and 6-311++G(3 df, 3 pd) basis sets, respectively. The structures of the intersystem crossings, which play a crucial role in these photo-isomerization reactions, are identified. The intermediates and transition structures of the ground state are also calculated to provide a qualitative explanation of the reaction pathways. The model investigations suggest that the preferred reaction route for 1 is as follows: singlet reactant → Franck-Condon region → triplet reactant → triplet transition state → intersystem crossing → intermediate → singlet transition state → photoproduct. In particular, the intersystem-crossing mechanism in this work gives a better explanation and supports the available experimental observations. Two types of reaction pathways that lead to final photoproducts are identified: (path I) ring expansion to form a cycloheptene ring and (path II) ring closure to form a methylcyclohexene structure. Both exhibit a biradical character. These theoretical results agree well with the available experimental observations. [ABSTRACT FROM AUTHOR]