Byrsonic Acid—the Clue to Floral Mimicry Involving Oil-Producing Flowers and Oil-Collecting Bees

Tetrapedia diversipes and other Apidae (Anthophoridae) may be deceived by floral similarities between Malpighiaceae and Orchidaceae of the Oncidiinae subtribe. The latter do not usually exudate floral oils. Thus, visitors may pollinate the flowers in a deceit/food/pollination syndrome. We studied the chemical compositions of Byrsonima intermedia (Malpighiaceae) floral oil and T. diversipes (Anthophoridae) cell provisions. From B. intermedia floral oil, we isolated a novel fatty acid (3R, 7R)-3,7-diacetoxy-docosanoic acid, here named byrsonic acid, and from T. diversipes cell provisions we isolated two novel fatty acid derivatives 3,7-dihydroxy-eicosanoic acid and 3,7-dihydroxy-docosanoic acid, here named tetrapedic acids A and B, respectively. The three fatty acid derivatives have common features: possess long chains (20 or 22 carbon atoms) with no double bond and either hydroxy or acetoxy groups at carbons 3 and 7. This characteristic was also encountered in the fatty acid moiety of oncidinol (2S, 3′R, 7′R)-1-acetyl-2-[3′, 7′-diacetoxyeicosanyl)-glycerol, a major floral oil constituent of several Oncidiinae species (Orchidaceae). Thus, both tetrapedic A (C20) and B (C22) could be the biotransformation products of oncidinol and byrsonic acid by T. diversipes hydrolases. These are the chemical clues for bee visitation and oil collecting from both plant species. The results indicate that the deceit/pollination syndrome should not be applied to all Oncidiinae flowers.     

Alkane Carbon-Hydrogen Bond Functionalization as a Tool Toward a Steric Parameter for Hydrotris(pyrazolyl)borate (Tpx) Ligands

The effect of a series of hydrotris(pyrazolyl)borate ligands (Tp^x) in the regioselectivity of the catalytic functionalization of the secondary carbon-hydrogen bonds of hexane with ethyl diazoacetate and Tp^xCuL as the catalysts has led to the definition of the relative steric parameter SP_R. The validity of the parameter has been assessed upon its correlation with the regioselectivity observed in several transformations (olefin cyclopropanation, C−H functionalization, C−H amidation), in all cases a good degree of fitting being observed.     

Patent Abstracts on Cellular Plastics

(US5019292): Granular detergent composition comprises: at least 1% detersive surfactant (I): 5–35% detergency builders (II); 1–25% naturally occurring hectorite clay ((Mg_3x Li _x )Si_4-y MeIII _y O₁₀(OH_2-z F _z )) - [(x+y) (x+y) Mn⁺]/n (III); and 1–10% additional fabric softener (IV) of formula (a) R₁R₂R₃N, (b) R₁OR₁NCOR₁₂: where MeIII is Al, Fe, or B, or y = 0; Mn⁺ is mono- or divalent metal; the clay (III) has a layer charge distribution (x+y) such that at least 50% of the layer charge is 0.23–0.31; R₁, = 6–20 C hydrocarbyl; R₂ = 1–20 C hydrocarbyl; R₃ = H or 1–20 C hydrocarbyl; R₁₀, R₁₁ = 1–22 C alk(en)yl, hydroxy alkyl, aryl, alkaryl; R₁₂ = H, 1–22 C alk(en)yl, aryl, alkaryl or OR₁₃; R₁₃ = 1–22 C alk(en)yl, aryl, alkaryl, or (c) a 1-(12–22 C alkyl) amide (1–4 C alkyl)-2-(12–22 C alkyl) imidazoline.     

Synthesis and Biological Evaluation of CF3Se-Substituted α-Amino Acid Derivatives

Several CF₃Se-substituted α-amino acid derivatives, such as (R)-2-amino-3-((trifluoromethyl)selanyl)propanoates ( 5 a / 6 a ), (S)-2-amino-4-((trifluoromethyl)selanyl)butanoates ( 5 b / 6 b ), (2R,3R)-2-amino-3-((trifluoromethyl)selanyl)butanoates ( 5 c / 6 c ), (R)-2-((S)-2-amino-3-phenylpropanamido)-3-((trifluoromethyl)selanyl)propanoates ( 11 a / 12 a ), and (R)-2-(2-aminoacetamido)-3-((trifluoromethyl)selanyl)propanoates ( 11 b / 12 b ), were readily synthesized from natural amino acids and [Me₄N][SeCF₃]. The primary in vitro cytotoxicity assays revealed that compounds 6 a , 11 a and 12 a were more effective cell growth inhibitors than the other tested CF₃Se-substituted derivatives towards MCF-7, HCT116, and SK-OV-3 cells, with their IC₅₀ values being less than 10 μM for MCF-7 and HCT116 cells. This study indicated the potentials of CF₃Se moiety as a pharmaceutically relevant group in the design and synthesis of novel biologically active molecules.     

Recognition by nonaromatic and stereochemical subunit-containing polyamides of the four Watson-Crick base pairs in the DNA minor groove

In order to develop an optimal subunit as a T‐recognition element in hairpin polyamides, 15 novel chirality‐modified polyamides containing (R)‐α,β‐diaminopropionic acid (^Rβ), (S)‐α,β‐diaminopropionic acid (^Sβ), (1R,3S)‐3‐aminocyclopentanecarboxylic acid (^RSCp), (1S,3R)‐3‐amino‐cyclopentanecarboxylic acid (^RSCp), (1R,3R)‐3‐aminocyclopentanecarboxylic acid (^RRCp) and (1S,3S)‐3‐amino‐cyclopentanecarboxylic acid (^SSCp) residues were synthesized. Their binding characteristics to DNA sequences 5′‐TGC N CAT‐3′/3′‐ACG N′ GTA‐5′ ( N?N′ =A ? T, T ? A, G ? C and C ? G) were systemically studied by surface plasmon resonance (SPR) and molecular simulation (MSim) techniques. SPR showed that polyamide 4 , AcIm‐^Sβ‐ImPy‐γ‐ImPy‐β‐Py‐βDp (β/^Sβ pair), bound to a DNA sequence containing a core binding site of 5′‐TGC A CAT‐3′ with a dissociation equilibrium constant (K_D) of 4.5×10^?8 m. This was a tenfold improvement in specificity over 5′‐TGCTCAT‐3′ (K_D=4.5×10^?7 M ). MSim studies supported the SPR results. More importantly, for the first time, we found that chiral 3‐aminocyclopentanecarboxylic acids in polyamides can be employed as base readers with only a small decrease in binding affinity to DNA. In particular, SPR showed that polyamide 9 (^RRCp/β pair) had a 15‐fold binding preference for 5′‐TGCTCAT‐3′ over 5′‐TGCACAT‐3′. A large difference in standard free energy change for A ? T over T ? A was determined (ΔΔG^o=5.9 kJ mol^?1), as was a twofold decrease in interaction energy by MSim. Moreover, a 1:1 stoichiometry ( 9 to 5′‐TGC T CAT‐3′/3′‐ACG A GTA‐5′) was shown by MSim to be optimal for the chiral five‐membered cycle to fit the minor groove. Collectively, the study suggests that the (S)‐α‐amino‐β‐aminopropionic acid and (1R,3R)‐3‐aminocyclopentanecarboxylic acid can serve as a T‐recognition element, and the stereochemistry and the nature of these subunits significantly influence binding properties in these recognition events. Subunit (1R,3R)‐3‐aminocyclopentanecarboxylic acid broadens our scope to design novel polyamides.     

Synthese und Reaktionen chiraler,von (R)-(−)-bzw. (S)-(+)-2-Methoxymethylpyrrolidin abgeleiteter Dithiocarbamate

Synthesis and Reactions of Chiral Dithiocarbamates Derived from (R)-(−)- or (S)-(+)-2- The synthesis, diastereoselective alkylation reactions, dithiocarboxylation, and aldol condensation of several substituted methyl (R¹ CH₂) (S)-2-(methoxymethyl)-pyrrolidine-1-dithiocarboxylates (S)- 2 and of the corresponding (R)-derivatives (R)- 2 are described. The new enantiomeric dithiocarbamates (S) -2a – e , and (R) -2a – d are obtained by reaction of (S)-(+)-[(S) -1 ] or (R)-(−)-2-(methoxymethyl)-pyrrolidine [(R) -1 ], respectively, with carbon disulfide in dry methanol/anhydrous sodium acetate and the appropriate alkylating agent. The cyclic ketene dithioacetals (S) -3 and (R) -3 are formed by dithiocarboxylation procedure of (S) -2a and (R) -2a whereas (S) -6 and (R) -6 are obtained by aldol reaction with isobutyraldehyde. (S)- 2c , d and (R) -2c , d react in a diastereoselective manner after deprotonation with n-BuLi or LiTMP/LiBr at −78°C in THF with alkyl halides to the enantiomeric compounds 4a /ent -4a, 4b /ent -4b and 5 /ent -5 , respectively.     

Preparation and application of chiral recognizable thermosensitive polymers and hydrogels consisting of N-methacryloyl-s-phenylalanine methyl ester

Amphiphilic random copolymers, poly(R-HPMA-co-S-PAM) and poly(HPMA-co-S-PAM), were prepared by radical copolymerization of N-methacryloyl-(S)-phenylalanine methyl ester (S-PAM) and N-[(R)-2-hydroxypropyl]methacrylamide (R-HPMA) or N-(2-hydroxypropyl)methacrylamide (HPMA) with various molar ratios of R-HPMA (or HPMA) (m) to S-PAM (n). Either aqueous solution of poly(R-HPMA-co-S-PAM) with the molar ratio of m : n = 0.81 : 0.19 or poly(HPMA-co-S-PAM) with the molar ratio of m : n = 0.79 : 0.21 exhibited the lower critical solution temperature (LCST) at 16°C. The LCST in the presence of (S)-(−)-phenylalanine (S-Phe) shifted from 16 to 20°C and 18°C for poly(R-HPMA-co-S-PAM) and poly(HPMA-co-S-PAM), respectively, whereas the LCST did not shift in the presence of (R)-(+)-phenylalanine (R-Phe). Thermosensitive Gel(R-HPMA-co-S-PAM) and Gel(HPMA-co-S-PAM) were also prepared from radical copolymerization of S-PAM and R-HPMA or HPMA in the presence of N,N′-ethylenebisacrylamide (EBAAm) as a crosslinker. When the gels shrunk at 40°C, the release of dansyl-(R)-phenylalanine (Dans-R-Phe) from the gel in which loaded Dans-R-Phe occurred was more easily done than that of Dans-S-Phe from the gel that loaded Dans-S-Phe. Thus, these thermosensitive copolymers and gels were found to exhibit chiral recognition for phenylalanine derivatives. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 228–236, 2001     

Ligand‐Assisted Palladium(II)/(IV) Oxidation for sp3 C?H Fluorination

The direct functionalization of inert sp³ C H bonds is limited to a few bond types. Although the activation of sp³ C H bonds can be accomplished under mild conditions using palladium catalysts, the subsequent functionalization is not trivial due to the high energy required to convert palladium(II) to palladium(IV). We have systematically studied the palladium oxidation using computation‐guided experiments for reactions involving strong chelation control. We find that a mild external ligand could significantly accelerate the oxidation of palladium(II) to palladium(IV) for strong bidentate directing groups. The acceleration is believed to be a result of ligand stabilization of both the palladium(II) and palladium(IV) intermediates.

     

Synthesis of [60]Fullerene‐Fused Tetralones via Palladium‐ Catalyzed Ketone‐Directed sp2 C?H Activation and sp3 C?H Functionalization

The palladium‐catalyzed ketone‐directed dual sp² C H activation and sp³ C H functionalization has been applied for fullerene functionalization for the first time. The sec‐alkyl aryl ketones have been exploited to react with [60]fullerene (C₆₀) to provide the novel and scarce C₆₀‐fused tetralones. The combined use of a highly active cationic palladium(II) catalyst and trifluoromethanesulfonic acid is crucial for the improvement of the reaction yield. A plausible reaction mechanism leading to the observed products has been proposed, and the electrochemistry of the fullerene products has also been investigated.

     

Novel imine from Hemsleya macrocarpa var. clavata

The new substance hemsleyin imine A (1) was isolated along with (2S,3S,4R,2′R)-2-(2′-hydroxytetracosanoylamino)-octadecan-1,3,4-triol (2), (2S,3R,4E,8E)-1-O-β-d-glucopyranosyl-3-hydroxy-2-(2′R-hydroxypalmitoylamino)-4,8-octadecadiene (3) from the rhizomes of Hemsleya macrocarpa var. clavata. Their chemical structures were established mainly by spectral analysis and chemical evidence. Compound 1 possesses the skeleton of an imine moiety, which is novel in natural products.     

Synthesis of dimer and oligomers from (R)-methyl hydnocarpate

We report synthesis and characterization of dimer and oligomer acids from chaulmoogra oil. (R)-Methyl hydnocarpate (methyl ester of the major fatty acid component of chaulmoogra oil) was brominated to give threo-2,3-dibromocyclopentane-1-methyl undecanoate. Formation of two diastereoisomers, viz., threo-2(R),3(R)-dibromocyclopentane-1(R)-methyl undecanoate and threo-2(S),3(S)-dibromocyclopentane-(R)-1-methyl undecanoate, was observed. Dehydrobromination of bromo derivatives using alcoholic KOH gave a cyclopentadiene derivative as intermediate, which underwent Diels-Alder reaction to give dimer and oligomer fatty acids. The products were characterized by ultraviolet, direct exposure probe-mass spectroscopy, ¹H nuclear magnetic resonance (NMR), and ¹³C NMR spectroscopic techniques.     

Fabrication and Performance of Solid Oxide Fuel Cells with La0.2Sr0.7TiO3–δ as Anode Support and La2NiO4+δ as Cathode

A novel fabrication process for solid oxide fuel cells (SOFCs) with La_0.2Sr_0.7TiO_3–δ (LST_A–) as anode support and La₂NiO_4+δ (LNO) as cathode material, which avoids complicated impregnation process, is designed and investigated. The LST_A– anode‐supported half cells are reduced at 1,200 °C in hydrogen atmosphere. Subsequently, the LNO cathode is sintered on the YSZ electrolyte at 1,200 °C in nitrogen atmosphere and then annealed in situ at 850 °C in air. The results of XRD analysis and electrical conductivity measurement indicate that the structure and electrochemical characteristics of LNO appear similar before and after the sintering processes of the cathode. By using La_0.6Sr_0.4CoO_3–δ (LSC) as current collector, the cell with LNO cathode sintered in nitrogen atmosphere exhibits the power density at 0.7 V of 235 mW cm⁻² at 800 °C. The ohmic resistance (R_S) and polarization resistance (R_P) are 0.373 and 0.452 Ω cm², respectively. Compared to that of the cell with the LNO cathode sintered in air, the sintering processes of the cell with the LNO cathode sintered in nitrogen atmosphere can result in better electrochemical performance of the cell mainly due to the decrease in R_S. The microstructures of the cells reveal a good adhesion between each layer.     

Isolation and structure of glucosylceramides from the starfish Cosmasterias lurida

From the water-insoluble lipid fraction of the methylene chloride/methanol extract of the starfish Cosmasterias lurida, two new glucosylceramides together with a known glucosylceramide, ophidiacerebroside E, were isolated by chromatographic procedures and characterized by spectroscopic (¹H and ¹³C nuclear magnetic resonance, mass spectrometry) methods. The new compounds were identified as (2S, 3R, 4E, 8E, 10E)-1-(β-d-glucopyranosyloxy)-3-hydroxy-2-[(R)-2-hydroxyheptadecanoyl)amino]-9-methyl-4,8,10-octadecatriene (3) and (2S,3R,4E,8E,10E)-1-(β-d-glucopyranosyloxy)-3-hydroxy-2-[(R)-2-hydroxyoctadecanoyl)amino]-9-methyl-4,8,10-octadecatriene (4).     

Multiple Oxidative Dehydrogenative Functionalization of Arylacetaldehydes Using Molecular Oxygen as Oxidant Leading to 2‐Oxo‐acetamidines

A novel copper‐catalyzed, multiple oxidative dehydrogenative functionalization of arylacetaldehydes leading to 2‐oxo‐acetamidine compounds has been developed. This transformation is highly efficient with dissociation of six hydrogens including two sp³ C H and one sp² C H bond activations. This method not only provides an efficient approach to 2‐oxo‐acetamidine compounds, but also offers a valuable mechanistic insight into this novel copper catalysis.     

Living functionalization of polymethacrylates by group transfer polymerization (GTP) using low ceiling temperature monomers

A living functionalization method for group transfer polymerization (GTP) has been developed for poly(alkyl methacrylates) using the sterically hindered monomer, methyl-2-phenylpropenoate (MPHA). The end-capping reactions of MPHA with living trimethylsilyl ketene acetal-ended poly(methyl methacrylate) (PMMA) chain ends have been systematically studied and characterized by size exclusion chromatography, vapor pressure osmometry, ultraviolet-visible, ¹H and ¹³C nuclear magnetic resonance spectroscopy. Although oligomerization of MPHA is observed at - 78° C, this is reversible and only monoaddition is observed at room temperature. In principle, various functional groups can be introduced into poly(alkyl methacrylates) via substituents on the aromatic ring of MPHA and related monomers. Amino-functionalized PMMA was prepared by end-capping reactions of living trimethylsilyl ketene acetal-ended PMMA with methyl E-3-(2-dimethylaminophenyl)-2-phenylacrylate.     

Chirality of macrolide pheromones of grain beetles in the generaOryzaephilusandCryptolestes and its implications for species specificity

The chiralities of macrolide lactone aggregation pheromones of five species of economically important grain beetles have been determined by capillary gas chromatographic separation of the diastereomeric (S)-O-acetyllactate derivatives of the hydroxy methyl esters derived from boron trifluoride-catalyzed cleavage of the macrolides in methanol. Chirally pure (Z)-3-dodecen-11-olide (I) is produced in theS configuration byCryptolestes ferrugineus (Stephens) and in theR configuration byOryzaephilus mercator (Fauvel). (Z,Z)-3,6-Dodecadien-11-olide (II) is produced in theR configuration by bothO. mercator andO. surinamensis (L.). (Z,Z)-5,8-Tetradecadien-13-olide (IV) is produced in theR configuration byO. surinamensis and as a 8515 mixture ofR andS isomers byC. turcicus. (Z)-5-Tetradecen-13-olide (V) is produced in the S configuration byC. pusillus (Schönherr) and as a 3367 mixture of theR andS isomers byC. turcicus (Grouvelle). The results indicate that in these cucujids, species specificity in pheromone response is maintained at least in part by pheromone chirality.Research supported by the Natural Sciences and Engineering Reseach Council of Canada, Operating Grants A3881, A0851 and A3785, and Strategic Grant G0958.     

Identification and Synthesis of the Sex Pheromone of the Madeira Mealybug, <Emphasis Type="Italic">Phenacoccus Madeirensis</Emphasis> Green

Two components were identified from aeration extracts of the virgin female Madeira mealybug, Phenacoccus madeirensis as trans-(1R,3R)-chrysanthemyl (R)-2-methylbutanoate and (R)-lavandulyl (R)-2-methylbutanoate (with a ratio of 3:1) by a combination of gas chromatography retention time matches, mass spectrometry, and microchemical tests. The structures and chirality of the compounds were confirmed by comparing with synthetic compounds. The synthetic trans-(1R,3R)-chrysanthemyl (R)-2-methylbutanoate was highly attractive to males in laboratory bioassays; the synthetic (R)-lavandulyl (R)-2-methylbutanoate was weakly attractive. No synergistic effect was observed when the mixture of the two compounds was tested.     

Effect of addition of organoaluminum and organoboron compounds in the stereospecific polymerization of acrylonitrile using dialkylmagnesium as catalyst

An attempt was made to clarify the effect of addition of organoaluminum and organoboron compounds in the stereospecific polymerization of acrylonitrile (AN) initiated by dialkylmagnesium (R₂Mg) above 100°C. The triad isotacticity (i.e. the content of mm (m: meso)) as well as the viscosity-average molecular weight (M?_v) of polyacrylonitrile (PAN) increased when trialkylaluminum (R₃Al) and trialkylboron (R₃B) were used as additives. Diisobutylaluminum hydride [(i-C₄H₉)₂AlH] was found to be the best additive. in the stereospecific polymerization of AN, giving PAN with higher (mm) content (0.63), higher M?_v value (5.2 × 10⁴), and a yield approximately double that obtained using (n-C₆H₁₃)₂Mg alone. When the (n-C₆H₁₃)₂Mg/(i-C₄H₉)₂AlH system was used, the yield, (mm), and M?_v of PAN increased with polymerization temperature (T_p); maximum values of yield, (mm), and M?_v were obtained at c. 130°C. The optimum amount of additives was approximately equimolar to R₂Mg as initiator. The ¹³C chemical shift of α-carbon in R₂Mg at 90°C shifted by mixing with R₃Al and R₃B, respectively, indicating the existence of interaction between R₂Mg and the additives. The main role of the additives is considered to be suppression of the self-association of R₂Mg by strong interaction with R₂Mg.     

Chiral Synthesis via Organoboranes 23. Enantioselective Ring Opening of meso-Epoxides with B-Halodiisopinocampheylboranes. The First General Synthesis of Optically Active 1,2-Halohydrins

B-Halodiisopinocampheylboranes, Ipc₂BX, where X is Cl, Br, or I, cleave cyclohexene oxide at low temperatures to give the 1,2-halohydrins, in 22, 84, and 91% enantiomeric excess (ee), respectively. 1,2-Epoxycyclohex-4-ene is converted to the bromohydrin and iodohydrin in 84 and 91% ee. cis-2,3-Epoxybutane, cis-3,4-epoxyhexane, and cyclopentene oxide were also studied with all three halides. In general, optical induction increases in the order I > Br > Cl for any given epoxide. Thus cis-2,3-epoxybutane furnishes the corresponding chlorohydrin in 35% ee, the bromohydrin in 69% ee, and the iodohydrin in 78% ee. In certain cases recrystallization provides essentially optically pure material, e.g., (1R, 2R)-2-bromocyclohexanol, (1R, 2R)-2-iodocyclohexanol and (1R, 2R)-2-iodocyclohex-4-en-1-ol. In all cases examined ^dIpc₂BX (derived from (+)-α-pinene) provide (1R, 2R) halohydrins, in which the enantiotopic S C—O bond is cleaved. Ring cleavage occurs in an anti-periplanar manner, consistent with an S_N2 type reaction pathway. Modified B-chloromonoisopinocampheylboranes, IpcBCl(OR), cleave cyclohexene oxide at a slower rate but furnish the chlorohydrin in up to 35% ee (R = Bnz). This study is not only a novel application of chiral haloboranes, but constitutes the first general synthesis of symmetrical optically active 1,2-halohydrins.