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PubMed1999

Compartive study of volatile components and fatty acids of plants and in vitro cultures of parsley (Petroselinum crispum (Mill) nym ex hill).

Volatile compounds from plants, callus tissue cultures, and cell suspensions of parsley (Petroselinum crispum) were captured during the growth cycle using a dynamic headspace extraction and were identified by gas chromatography-mass spectrometry. Parsley plants were found to produce mainly monoterpenes, and the compound of major abundance was p-1,3,8-menthatriene, followed by beta-phellandrene and apiole. Callus cultures and cell suspensions produced aldehydes (nonanal and decanal) that were also detected in parsley plant. The former also produced limonene, acetophenone, and benzotiazol; these were not observed in the plants. The production of volatiles in plants, callus tissue, and cell suspensions was found to be time-dependent. Free and bound fatty acids were also monitored by an in situ method. Palmitic (C16:0) and stearic (C18:0) acids were the most abundant fatty acids in all materials; however, higher levels were found in plants. On the other hand, the unsaturated C16:1 and C16:3 were not detected in the in vitro cultures.

Aldehydes↗
PubMed1989

2(1H)-quinolinones with cardiac stimulant activity. 2. Synthesis and biological activities of 6-(N-linked, five-membered heteroaryl) derivatives.

A series of 6-(N-linked, five-membered heteroaryl)-2(1H)-quinolinone derivatives was synthesized and evaluated for cardiotonic activity. Most compounds were prepared by sulfuric acid catalyzed cyclization of an N-(4-heteroarylphenyl)-3-ethoxypropenamide or by condensation of a 2-amino-5-heteroarylbenzaldehyde or -acetophenone derivative with the ylide derived from triethyl phosphonoacetate. In anesthetized dogs, 6-imidazol-1-yl-8-methyl-2(1H)-quinolinone (3; 25 micrograms/kg) produced a greater increase in cardiac contractility (percentage increase in dP/dt max) than alternative 6-(five-membered heteroaryl)-substituted analogues (4-8). Introduction of 4-methyl (10) or 2,4-dimethyl (13) substituents into the imidazole ring of 3 produced a marked increase in inotropic activity, and these compounds were some 10 and 5 times more potent than milrinone. Most of these quinolinones also displayed positive inotropic effects (decrease in QA interval) in conscious dogs after oral administration (0.0625-1 mg/kg) and in many cases (3, 5-7, 9, 11, 13, 16) there was little difference in activities at both the 1- and 3-h time points. Compound 13 (62.5, 125, 250 micrograms/kg po) demonstrated dose-related cardiac stimulant activity which, in contrast to milrinone, was maintained over the whole 7-h test period. No changes in heart rate were detected at any dose level and compounds 3, 9, 10, and 13 also displayed high selectivity for the stimulation of cardiac contractile force rather than heart rate in the Starling dog heart-lung preparation. Increases in dP/dt max of approximately 50% were accompanied by heart rate changes of less than 10 beats/minute. Physicochemical measurements gave a log P of 1.64 for 13 with pKa values of 7.13 +/- 0.04 and 11.5 +/- 0.2 for the imidazole and quinolinone moieties, respectively. X-ray structural analysis of 13 showed the imidazole and quinolinone rings at 52 degrees to one another in close agreement with the minimum-energy conformation (30 degrees) suggested by PCILO calculations. 6-(2,4-Dimethylimidazol-1-yl)-8-methyl-2-(1H)-quinolinone (13, UK-61,260) is currently undergoing phase II clinical evaluation in congestive heart failure patients.

Animals↗
PubMed1985

3,4-O-diacetylisoproterenol. Preparation, structure proof, and beta-receptor effect.

Direct acetylation of isoproterenol by selective O-acetylation using CH3COCl/CF3COOH was shown to lead to the formation of 2-(3,4-diacetoxyphenyl)-2-chloro-N-isopropyl-1-ethanamine and not to 3,4-O-diacetylisoproterenol. The latter was prepared by reduction of 3,4-diacetoxy(2-isopropylamino)acetophenone and its structure confirmed by IR, 1H, 13C NMR, mass spectral, and elemental analysis. The two compounds were tested for activity on beta-receptors. Efficacy and affinity on beta 1-receptors were found identical with the effect of isoproterenol. So was efficacy on beta2-receptors, while affinity was lower for the chloro compounds than for isoproterenol and diacetylisoproterenol which exhibited identical affinity.

Acetylation↗
PubMed1979

Studies on analgesic agents. 1.1a Preparation of 1,2-diphenyl-2-(4-substituted 1-piperazinyl)ethanol derivatives and structure-activity relationships.

The preparation and analgesic activity of a series of the title compounds (8-55 and 57) are described. The intermediates, 2-phenyl-2-(1-piperazinyl)acetophenones 5 and 6, were prepared from benzyl phenyl ketones 3 via their bromides 4. On reduction, compounds 5 afforded the titled compounds 8-12, 16, and 26-48. Compounds 13-15 and 17-25 were obtained by alkylation or benzylation of 1.2-diphenyl-2-(1-piperazinyl)ethanols 7 derived from 6 by reduction. The reduction of 5 and 6 with metal hydrides predominantly gave the erythro isomers. The erythro isomers were remarkably more active than their threo isomers. The more active members in this series of compounds were 16 and derivatives 35 and 37-44 of dl-erythro-1-phenyl-2-(substituted phenyl)-2-[4-(p-methoxybenzyl)-1-piperazinyl]ethanol. Compounds 16, 43, and 44 were the most active with a potency of about two to three times that of codeine. Racemates 16 and 38 were resolved into their optical isomers and it was found that (-)-16 and (+)-38 were more potent than their antipodes. Structure-activity relationship are discussed.

Analgesics↗
PubMed1977

Synthesis and beta-adrenergic blocking activity of a novel class of aromatic oxime ethers.

A new series of beta-adrenergic blocking amines containing an oximino-propanolic chain linked to an aromatic nucleus was synthesized. Most of the derivatives are characterized by beta2-selectivity. The structure-activity relationship are discussed. One of the compounds, selected for further studies, was more active on the trachea than on the atria of guinea pig, 155 times in vitro and 26 times in vivo. In comparison, butoxamine's beta2-selectivity is 13 in vitro and only 2 in vivo. With a series of 30 acetophenone oxime derivatives, no quantitative structure-activity relationships could be detected.

Adrenergic beta-Antagonists↗
PubMed1983

N-(4-substituted-thiazolyl)oxamic acid derivatives, a new series of potent, orally active antiallergy agents.

A series of N-(4-substituted-thiazolyl)oxamic acid derivatives were synthesized and tested for antiallergy activity in the rat PCA model. These compounds were conveniently prepared by treatment of the appropriate acetophenone with thiourea and iodine or by reaction of the chloroacetylbenzene with thiourea to give the corresponding aminothiazoles; subsequent condensation with ethyloxalyl chloride gave the thiazolyloxamates. Many of the analogues showed a 50% inhibition at less than 2 mg/kg po or less than 0.4 mg/kg iv and were significantly more potent than disodium cromoglycate, which in the rat PCA model is orally inactive and gives a 50% inhibition at 1.2 mg/kg iv. Hydrolysis of the oxamates generally resulted in enhanced activities, while substitution of the phenyl ring with a variety of substituents (e.g., 4-F, 4-OEt, and 4-NHCOCH3) did not significantly enhance the activity of the unsubstituted phenyl derivative. One of the ethanolamine salts, N-[4-(1,4-benzodioxan-6-yl)-2-thiazolyl]oxamic acid ethanolamine salt (61, PRH-836-EA), has been selected for further pharmacological evaluation.

Animals↗
PubMed1984

Potential inhibitors of nucleotide biosynthesis. 2. Halomethyl ketone derivatives of pyrimidine nucleosides.

Several halomethyl ketone derivatives of pyrimidine nucleosides have been prepared for evaluation as cytotoxic agents. The first series are 1-(8-halo-2,5,6,8- tetradeoxy -beta-D-erythro-oct-7 - ulofuranosyl )thymines (7-9), whereas the second type are halo derivatives of acetophenone (12-14 and 16). These compounds are cytotoxic, and one (13) showed activity against the P388 leukemia in vivo.

Animals↗
PubMed1998

Synthesis, anticonvulsant activity, and structure-activity relationships of sodium channel blocking 3-aminopyrroles.

Starting from the corresponding acetophenone and glycine derivatives, a series of new 3-aminopyrroles was synthesized in few steps. Using this procedure with hydrazine and hydroxylamine instead of the glycinates provides access to 3-aminopyrazoles and 5-amino 1,2-oxazoles. The various derivatives were tested for anticonvulsant activity in a variety of test models. Several compounds exhibit considerable activity with a remarkable lack of neurotoxicity. 4-(4-Bromophenyl)-3-morpholinopyrrole-2-carboxylic acid methyl ester, 3, proved to be the most active compound. It was protective in the maximal electroshock seizure (MES) test in rats with an oral ED50 of 2.5 mg/kg with no neurotoxicity noted at doses up to 500 mg/kg. Compound 3 blocks sodium channels in a frequency-dependent manner. The essential structural features which could be responsible for an interaction with an active site of the voltage-dependent sodium channel are established within a suggested pharmacophore model.

Animals↗
PubMed2000

How borane reagents based on alpha-pinene control stereoselectivity in the reductions of carbonyl groups with different stereogenic elements. 3. The effect of the relative size and conformation of the carbonyl substituents on the stereoselectivity of the Ipc(2)BCl, Eap(2)BCl, B-t-Bu-IpcBCl, and B-t-Bu-EapBCl reagents. A semiempirical study

The reductions of a more elaborate prostereogenic nonchiral and chiral ketones with the representative borane reagents derived from (+)-alpha-pinene confirm that the overall stereoselectivity, similarly to the previously studied reductions of benzaldehyde and acetophenone, is also controlled, early along the reaction coordinate, by the structure of the borane reagent. The stereoselectivity reflects the energy differences among syn-1, 3-interactions of the smallest of the three boron substituents in the reacting borane conformation with the two carbonyl substituents in the substrate. For the B-alkyl-IpcBCl reagents and the R(S)-CO-R(L) substrates, these are the interactions of the B-Cl with the C-R(S) and C-R(L) bonds. To minimize developing intermolecular syn-1,3-interactions with the reagent's B-Cl bond during the reaction, in the conformationally mobile R(S)-CO-R(L) systems, the R(L) and R(S) groups seek to adopt a more reactive conformation even at the expense of the unfavorable intramolecular interactions.

Journal Article↗
PubMed2000

On the Z-E photoisomerization of chiral 2-pentenoate esters: stationary irradiations, laser-flash photolysis studies, and theoretical calculations.

Chiral pentenoates 1-3 in both Z and E isomeric forms underwent stationary irradiations in several solvents and in the presence of different photosensitizers. The photostationary-state ratio has been determined for each Z/E couple showing a predominance of the thermodynamically more stable isomer for 1 and 3. Moreover, transient species were generated by pulsed laser excitation and detected by their characteristic ultraviolet absorptions, being the first time that enoate-originated triplets are detected. Stern-Volmer quenching studies afforded a quantitative measure for the efficiency of the photosensitization processes induced by benzophenone or acetophenone and allowed the determination of the corresponding quenching rate constants. Density functional calculations permitted the determination of the geometries and the energies of the diastereomeric excited states. Two diastereomeric orthogonal and two diastereomeric planar structures result as a consequence of the presence of a chiral substituent. The orthogonal triplets are the energy minima in all cases, whereas the planar triplets are the transition states linking these orthogonal structures, the corresponding energy barriers being 8-10 kcal mol(-1) for enoates 1-3. The computed S(0) to T(1) excitation energies show a trend which is consistent with the quenching rate constants. On the other hand, the triplet lifetimes determined for 1 and 2 are unusually long (1-20 micros) if compared with the data already described for several enones, in the range of nanoseconds. This fact has been rationalized from calculations of spin-orbit coupling at several points of the T(1) potential energy surface. This coupling is maximum for structures with a torsional angle close to 45 degrees, which are 4-5 kcal mol(-1) above the minima of T(1). Calculations done on the hypothetical aldehyde 4 and methyl vinyl ketone show much lower energy barriers, thus accounting for the shorter lifetimes reported for enone triplets.

Esters↗
PubMed2000

Rational design of highly diastereoselective, organic base-catalyzed, room-temperature Michael addition reactions.

Via the rational design of a single-preferred transition state, stabilized by electron donor-acceptor-type attractive interactions, structural and geometric requirements for the corresponding starting compounds have been determined. The Ni(II) complex of the Schiff base of glycine with o-[N-alpha-picolylamino]acetophenone, as a nucleophilic glycine equivalent, and N-(trans-enoyl)oxazolidin-2-ones, as derivatives of an alpha,beta-unsaturated carboxylic acid, were found to be the substrates of choice featuring geometric/conformational homogeneity and high reactivity. The corresponding Michael addition reactions were found to proceed at room temperature in the presence of catalytic amounts of DBU to afford quantitatively the addition products with virtually complete diastereoselectivity. Acidic decomposition of the products followed by treatment of the reaction mixture with NH4OH gave rise to the diastereomerically pure 3-substituted pyroglutamic acids.

Catalysis↗
PubMed2000

Acyclic stereoselection in the reaction of nucleophilic reagents with chiral N-acyliminium ions generated from N-

Optically active N-[1-(phenylsulfonyl)alkyl]imidazolidin-2-ones react at low temperature in the presence of tin tetrachloride to give acyclic N-acyliminium ions. These electrophilic substrates give addition products upon reaction with pi-nucleophiles. Allyltrimethylsilane affords the corresponding allylated products in good yields and high diastereoselectivity. The stereochemical outcome of this process can be rationalized by taking into account the preference of the intermediate N-acyliminium ion for an E configuration that favors the attack of the nucleophile from the si-si face. Disappointing results are obtained using silyl ketene acetals; conversely trimethylsilyl enol ether of acetophenone gives the corresponding adducts in high diastereoselectivity. The utilization of trimethylsilyl enol ether of 2-acetylfuran is particularly interesting since the corresponding adducts are obtained with good diastereoselectivity and the furan ring could be amenable of further synthetic transformations.

Journal Article↗
PubMed2000

Quantum yields of the initiation step and chain propagation turnovers in S(RN)1 reactions: photostimulated reaction of 1-iodo-2-methyl-2-phenyl propane with carbanions in DMSO

Neophyl radicals were generated by photoinduced electron transfer (PET) from a suitable donor to the neophyl iodide (1, 1-iodo-2-methyl-2-phenylpropane). The PET reaction of 1 with the enolate anion of cyclohexenone (2) afforded mainly the reduction products tert-butylbenzene (5) and the rearranged isobutylbenzene (6), arising from hydrogen abstraction of the neophyl radical (15) and the rearranged radical 16 intermediates, respectively. The photostimulated reaction of 1 with 2 in the presence of di-tert-butylnitroxide, as a radical trap, afforded adduct 10 in 57% yield. The photoinduced reaction of the enolate anion of acetophenone (3) with 1 gave the substitution products 11 (50%) and 12 (16%), which arise from the coupling of 3 with radicals 15 and 16, respectively. The rate constant obtained for the addition of anion 3 to radical 15 was 1.2 x 10(5) M(-)(1) s(-)(1), by the use of the rearrangement of this radical as a clock reaction. The anion of nitromethane (4) was almost unreactive at the initiation step, but in the presence of 2 under irradiation, it gave high yields (67%) of the substitution product 13 and only 2% of the rearranged product 14. When the ratio of 4 to 1 was diminished, it was possible to observe both substitution products 13 and 14 in 16% and 6.4% yields, respectively. These last results allowed us to estimate the coupling rate constant of neophyl radicals 15 with anion 4 to be at least of the order of 10(6) M(-)(1) s(-)(1). Although the overall quantum yield determined (lambda = 350 nm) for the studied reactions is below 1, the chain lengths (Phi(propagation)) for the reaction of 1 with anions 3 and 4 are 127 and 2, respectively.

Journal Article↗
PubMed2001

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 MnL(2) 3a or VClL(2) 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 beta-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.

Journal Article↗
PubMed2001

Photoreaction of 2-halo-N-pyridinylbenzamide: intramolecular cyclization mechanism of phenyl radical assisted with n-complexation of chlorine radical.

The photochemical behavior of 2-halo-N-pyridinylbenzamide (1-4 in Chart 1) was studied. The photoreaction of 2-chloro-N-pyridinylbenzamides 1a, 2a, 3a, and 4 afforded photocyclized products, benzo[c]naphthyridinones (6-9 and 16), in high yield, whereas the bromo analogues 1b, 2b, and 3b produced extensively photoreduced products, N-pyridinylbenzamides (1c, 10, and 11), with minor photocyclized product. Since the photocyclization reaction of 2-chloro-N-pyridinylbenzamide is retarded by the presence of oxygen and sensitized by the presence of a triplet sensitizer, acetone or acetophenone, a triplet state of the chloro analogue is involved in the reaction. Since several radical intermediates, particularly n-complexes of chlorine radical, are identified in the laser flash photolysis of 2-chloro-N-pyridinylbenzamide, an intramolecular cyclization mechanism of phenyl radical assisted with n-complexation of chlorine radical for the cyclization reaction is proposed: the triplet state (78 kcal/mol) of the chloro analogue (1a), which is populated by the excitation of 1a undergoes a homolytic cleavage of the C-Cl bond to give phenyl and chlorine radicals; while chlorine radical holds the neighbor pyridinyl ring with its n-complexation, the intramolecular arylation of the phenyl radical with the pyridinyl ring proceeds to produce a conjugated 2,3-dihydropyridinyl radical and then the conjugated radical aromatizes to afford a cyclized product, benzo[c]naphthyridinone by ejecting a hydrogen. The photoreduction product can be formed by hydrogen atom abstraction of the phenyl sigma radical from the environment.

Journal Article↗
PubMed2002

Practical synthesis of optically active amino alcohols via asymmetric transfer hydrogenation of functionalized aromatic ketones.

2-Substituted acetophenones such as 2-cyano-, 2-azido-, or 2-nitroacetophenones were effectively reduced with a mixture of HCOOH/N(C(2)H(5))(3) containing a chiral Ru(II) catalyst, RuCl[(S,S)-N-(p-toluenesulfonyl)-1,2-diphenylethylenediamine](p-cymene), giving the corresponding optically active alcohols, which can be converted to optically active amino alcohols with excellent ee's. Similarly, the reaction of 2-benzoylacetophenone with the same Ru catalyst gave a quantitative yield of the corresponding optically active 1,3-diol with 99% ee.

Journal Article↗
PubMed2002

Asymmetric synthesis of anti- and syn-beta-amino alcohols by reductive cross-coupling of transition metal-coordinated planar chiral arylaldehydes with aldimines.

Samarium iodide-mediated cross-coupling of N-tosyl ferrocenylideneamine with planar chiral ferrocenecarboxaldehydes or benzaldehyde chromium complexes gave diastereoselectively the corresponding anti-beta-amino alcohol derivatives in good yields, while N-tosyl benzylideneamine produced syn-beta-amino alcohols by coupling with planar chiral arylaldehydes. Dynamic kinetic resolution of a configurationally equilibrated reactive species generated from achiral N-tosyl ferrocenilideneamine and benzylideneamine by reduction with samarium iodide was observed in the cross-coupling with planar chiral arylaldehydes giving both antipodes of beta-amino alcohols depending on the planar chirality. The obtained anti-beta-amino alcohol with the ferrocene ring was utilized as a chiral ligand for catalytic asymmetric reduction of acetophenone.

Journal Article↗
PubMed2002

Model compound studies of the beta-O-4 linkage in lignin: absolute rate expressions for beta-scission of phenoxyl radical from 1-phenyl-2-phenoxyethanol-1-yl radical.

Arrhenius rate expressions were determined for beta-scission of phenoxyl radical from 1-phenyl-2-phenoxyethanol-1-yl, PhC*(OH)CH2OPh (V). Ketyl radical V was competitively trapped by thiophenol to yield PhCH(OH)CH2OPh in competition with beta-scission to yield phenoxyl radical and acetophenone. A basis rate expression for hydrogen atom abstraction by sec-phenethyl alcohol, PhC*(OH)CH3, from thiophenol, log(k(abs)/M(-1) s(-1)) = (8.88 +/- 0.24) - (6.07 +/- 0.34)/theta, theta = 2.303RT, was determined by competing hydrogen atom abstraction with radical self-termination. Self-termination rates for PhC*(OH)CH3 were calculated using the Smoluchowski equation employing experimental diffusion coefficients of the parent alcohol, PhCH(OH)CH3, as a model for the radical. The hydrogen abstraction basis reaction was employed to determine the activation barrier for the beta-scission of phenoxyl from 1-phenyl-2-phenoxyethanol-1-yl (V): log(k beta)/s(-1)) = (12.85 +/- 0.22) - (15.06 +/- 0.38)/theta, k beta (298 K) ca. (64.0 s(-1) in benzene), and log(k beta /s(-1)) = (12.50 +/- 0.18) - (14.46 +/- 0.30)/theta, k beta (298 K) = 78.7 s(-1) in benzene containing 0.8 M 2-propanol. B3LYP/cc-PVTZ electronic structure calculations predict that intramolecular hydrogen bonding between the alpha-OH and the -OPh leaving group of ketyl radical (V) stabilizes both ground- and transition-state structures. The computed activation barrier, 14.9 kcal/mol, is in good agreement with the experimental activation barrier.

Carbohydrate Conformation↗