Amine Substitution Research Articles

Intramolecular photoaddition reactions of (aminoalkyl)styrylamides

The photochemical reactions of a family of styrene—spacer—amine molecules in which the spacer consists of a rigid amide group in the middle of a flexible alkane chain have been investigated. Our study of the photophysics of these molecules has shown that the amide linker can facilitate intramolecular styrene—amine exciplex formation (J. Phys. Chem., in press). We report here the photochemical behavior of these amide-linked (aminoalkyl) styrylamides. Several tertiary amines are found to undergo regioselective α-C-H addition to the styrene double bond resulting in the formation of medium-ring lactams. A secondary amine undergoes N-H addition yielding an azalactam. The dependence of these reactions upon spacer structure, amine and amide substitution, and solvent polarity is discussed.

Density Functional Theory/GIAO Studies of the 13C, 15N, and 1H NMR Chemical Shifts in Aminopyrimidines and Aminobenzenes: Relationships to Electron Densities and Amine Group Orientations

The dependence of the 13C, 15N, and 1H isotropic NMR chemical shifts on amine substitution of aromatic ring systems are examined both experimentally and by DFT/GIAO (density functional theory/gauge including atomic orbitals) methods. There are large, monotonic decreases in the chemical shifts at odd-numbered (ortho and para) pyrimidine ring positions which do not occur at the even-numbered (ipso and meta) atoms as amine groups progressively replace hydrogens at the latter positions. This behavior parallels the computed 2pz electron densities which for the pyrimidine series increase monotonically at N1, N3, and C5 but exhibit small changes at the C2, C4, and C6 positions. Identical trends are noted for the aminobenzenes. The ring atom chemical shifts and 2pz electron densities at ortho and para (but not meta) positions are quite sensitive to the orientations of the amine groups which are pyramidalized as the result of balance between delocalization with the ring and the use of strongly directed sp3 orbital...

N, N-dimesylimides and N, N-dinosylimides as new leaving groups for the stereoselective nucleophilic substitution of amines

The enantiospecific transformation of the optically active amines 1 and 2 via the nucleophilic substitution of the N, N-dimesylimides ( 1Ms, 2Ms) and the N, N-dinosylimides ( 1Ns, 2Ns) to the corresponding alcohols 3 and 4 is reported. Different oxygen nucleophiles were used and the alcohol products were enriched with 74–95% of the enantiomer formed by inversion of configuration.

Porphyrins covalently bound to polystyrene II. an efficient model of monooxygenase reactivity

A simple and efficient method for the preparation of metalloporphyrin catalyst bound to benzhydryl amine substituted polystyrene via amide bond was elaborated. Catalytic efficiency of the Fe 3+ or Mn 3+ metallocomplexes of these porphyrin-benzhydryl amido-polystyrene catalysts was studied at the epoxidation reactions in the systems syrene/iodosobenzene or t-butyl hydroperoxide/pyridine or imidazole (axial ligands). The rate of substrate conversion (turnover of the catalytic centre) as a function of the density of saturation of the benzhydryl amine substitution of the resin is discussed.

Degradation of alkanolamine blends by carbon dioxide

AbstractAqueous solutions of MDEA, MDEA + DEA and MDEA + MEA containing 4.2 kmol/m3 total amine, were contacted with CO2 at a partial pressure of 2.58 MPa and temperatures ranging from 120 to 180°C, in a stainless steel batch reactor. The reaction products include the known degradation compounds of the amines as well as products formed from secondary interactions in the amine blends. The rate of degradation was first order in the amines and, in magnitude, followed the sequence MDEA < MEA < DEA. Furthermore, the rate constant for MDEA was independent of amine substitution level and blend constituents. From a practical standpoint, MDEA + DEA blends would require frequent DEA make‐up to maintain treating efficiency.

Synthesis and characterization of tritium‐labeled RU486

Abstract[3H]RU38486 (RU486) was synthesized from its penultimate precursor, desmethyl RU486, by substitution of the secondary amine with tritiated methyl iodide; specific activity 85 Ci/mmol. Ligand binding studies confirm that RU486 binds with high affinity to human progesterone receptor type A (PR‐A) and progesterone receptor type B (PR‐B).

Site-Directed Mutation in Conserved Anionic Regions of Guinea Pig Liver Transglutaminase

Transglutaminases (EC 2.3.2.13) catalyze the formation of ϵ-(γ-glutamyl) lysine cross-links and the substitution of primary amines for the γ-carboxamide groups of protein-bound glutamine residues. There are conserved anionic regions in transglutaminases, some of which are thought to be possible calcium-binding sites. By site-directed mutagenesis, three mutant forms of recombinant guinea-pig liver transglutaminase, in which some acidic amino acid residues in two conserved regions became nonionic, were expressed in Escherichia coli: TGM1, with Asp-231 and -232 changed to Asn; TGMS, with Glu-445, -448, -449, -450, and -452 changed to Gin; and TGM3, with the mutations of both TGM1 and TGM2. The size and level of synthesis of the mutant proteins were unchanged when monitored by immunoblotting. All mutants retained enzyme activity, and their apparent K m values for substrates during histamine incorporation into acetyl α s1-casein were similar to those of the wild-type enzyme, but their V max values were smaller. The deamidation rate of glutamine residues in the acetyl α s1-casein was unaffected, but the rate of protein cross-linking catalyzed by these mutants was very low. All mutations caused with the enzyme a decrease in the sensitivity to activation by calcium and an increase in the sensitivity to inhibition by GTP. These results indicated that the negative charges of some acidic amino acid residues in the two conserved anionic regions of transglutaminase are not essential for its activity but the loss of their negative charges affects some catalytic properties.

Influence of amine substituents on 5-HT2A versus 5-HT2C binding of phenylalkyl- and indolylalkylamines.

The effect of 15 different amine substituents on 5-HT2A and 5-HT2C serotonin receptor binding was investigated for two series of compounds (i.e., phenylalkylamine and indolylalkylamine derivatives). In general, amine substitution decreases receptor affinity; however, N-(4-bromobenzyl) substitution results in compounds that bind at 5-HT2A receptors with high affinity (Ki < 1 nM) and with > 100-fold selectivity. Although parallel structural modification in the two series result in parallel shifts in 5-HT2C binding, these same modifications alter 5-HT2A binding in a less consistent manner.

Nucleophilic substitution of chiral amine N, N-ditosylderivatives

The chiral transformation of the optically active amine 10 to the corresponding alcohol 2 with opposite configuration is reported. The transformation is carried out via an S N2 type reaction of the N, N-ditosylimide, -NTs 2, by nucleophilic attack of the hydroxide, acetate or benzoate ion to give an inversion degree of 85–100%. 0–34% stereoselectivity was obtained in the corresponding chloride nucleophilic substitutions. Separation parameters for the chromatographic enantioseparations of the amines 10–12, the chlorides 4,7,9 and the alcohol 2 using a chemically bonded cyclodextrin GLC column are discussed.

Synthesis and pharmacological evaluation of hexahydrofluorenamines as noncompetitive antagonists at the N-methyl-D-aspartate receptor.

The noncompetitive (PCP) site of the N-methyl-D-aspartate (NMDA) receptor complex has been implicated in a number of pathologies, including the etiology of ischemic stroke. Recent testing has shown that cis-1,2,3,4,9,9a-hexahydro-N-methyl-4aH-fluoren-4a-amine (1), a rigid analog of PCP, is a potent antagonist at this site (IC50 = 30 nM for displacement of [3H]TCP). On the basis of this finding, a number of derivatives encompassing variations in stereochemistry, amine substitution and position, aromatic and aliphatic ring substitution, and heteroatom ring substitution have been prepared to explore the structure-activity relationships around this ring system. All compounds were evaluated for their PCP receptor affinity; potent compounds were also tested in vitro (cultured neurons) and in vivo (prevention of NMDA-induced lethality in mice). The present hexahydrofluorenamines demonstrated a wide range of potencies, with optimal affinity concentrated in analogs containing a heteroatom (sulfur) in the B ring (IC50 of 11 nM versus [3H]TCP for 16b), methyl substitution on the amine, and R stereochemistry at the 4a position. No significant improvement in affinity was seen with aromatic ring substitution. Aliphatic ring substitution, large amine substituents, and alterations in the position of amine substitution on the ring system resulted in a loss of potency. To explore the effect of simultaneous hydrogen bonding with a putative receptor atom from two directions, the 2-hydroxymethyl derivatives were prepared. This substitution resulted in a loss in receptor binding affinity. Molecular modeling, X-ray, and NMR studies have been used to determine an optimal conformation of the hexahydrofluoreneamines at the receptor site.

Stimulation of Microsomal Superoxide ProductionIn Vitroby Selected Munition Compounds

Stimulation of microsomal superoxide production invitro was measured for various nitroaromatic substrates including methyl viologen, selected key munitions pollutants, and amines that can be formed from the munitions in the environment. Superoxide production mediated by microsomes from hepatic extracts required the addition of a redox active substrate and the cofactor NADPH. In the system, production of superoxide radical was stimulated by four of the five environmental munitions pollutants tested in the order: 1,3,5-trinitrobenzene > 2,4,6-trinitrotoluene > 1,3-dinitrobenzene >2,4-dinitrotoluene. For all the parent munition compounds stimulating superoxide production, substitution of analogous amines as substrates resulted in significantly reduced production rates. In general, rates of superoxide production stimulated by the munitions compounds correlated well with their capacity to be reduced biologically.

Role of the B-ring substituent in the fluorescence of colchicinoid-tubulin and allocolchicinoid-tubulin complexes.

Fluorescence spectra of several B-ring derivatives of allocolchicine in a variety of solvents have been obtained. The quantum yields of the allocolchicine derivatives decreased with amine substitution at the C-7 position [R = H greater than NH2 much greater than NHCH3 greater than N(CH3)2]. The relative fluorescent intensities of the aminoallocolchicinoids [R = NH2, NHCH3, N(CH3)2] bound to tubulin were significantly less than the fluorescent intensities of tubulin-bound allocolchicine (R = NHCOCH3) and deacetamidoallocolchicine (R = H). The low fluorescent intensities of the aminoallocolchicinoids in solvents and bound to tubulin could be explained by exciplex formation between the lone pair of electrons on the nitrogen and the allocolchicinoid pi-system, which leads to quenching of the allocolchicinoid fluorescence. Direct evidence for exciplex formation between the C-7 amine nitrogen and the allocolchicinoid pi-system was found in the emission spectrum of N-methyldemeallocolchicine [R = N(CH3)2] in dioxane. The quantum yields of the aminoallocolchicinoids in glycerol were higher than would be predicted on the basis of solvent dielectric effects. Glycerol appears to increase the quantum yields of the aminoallocolchicinoids through both viscosity and hydrogen-bonding effects. The latter effect serves to sequester the lone pair of electrons on the nitrogen, decreasing its ability to interact with the pi-system of the allocolchicinoid. It is concluded that the fluorescent properties of colchicinoids and allocolchicinoids in glycerol are not reliable indicators of the fluorescent properties of the molecules bound to tubulin.(ABSTRACT TRUNCATED AT 250 WORDS)

Mechanisms and stereochemistry of amine substitution reactions at the carbon-nitrogen double bond

The reaction of (Z)-O-methyl-nitrobenzohydroximoyl chloride [4-NO 2 C 6 H 4 C(CI)=NOCH 3 ] with morpholine, piperidine, pyrrolidine, and azetidine gives the corresponding (Z)-amidoximes (4-NO 2 C 6 H 4 C(NR 1 R 2 )=NOCH 3 ]. The rate equations for these reactions in benzene solution contain both first-order and second-order terms in amine

Functionalized congener approach to muscarinic antagonists: analogues of pirenzepine.

The M1-selective muscarinic receptor antagonist pirenzepine 6H-pyrido[2,3-b][1,4]benzodiazepin-6-one) was derivatized to explore points of attachment of functionalized side chains for the synthesis of receptor probes and ligands for affinity chromatography. The analogues prepared were evaluated in competitive binding assays versus [3H]-N-methylscopolamine at four muscarinic receptor subtypes (m1AChR-m4AChR) in membranes from rat heart tissue and transfected A9L cells. 9-(Hydroxymethyl)pirenzepine, 8-(methylthio)pirenzepine, and a series of 8-aminosulfonyl derivatives were synthesized. Several 5-substituted analogues of pirenzepine also were prepared. An alternate series of analogues substituted on the 4-position of the piperazine ring was prepared by reaction of 4-desmethylpirenzepine with various electrophiles. An N-chloroethyl analogue of pirenzepine was shown to form a reactive aziridine species in aqueous buffer yet failed to affinity label muscarinic receptors. Within a series of aminoalkyl analogues, the affinity increased as the length of the alkyl chain increased. Shorter chain analogues were generally much less potent than pirenzepine, and longer analogues (7-10 carbons) were roughly as potent as pirenzepine at m1 receptors, but were nonselective. Depending on the methylene chain length, acylation or alkyl substitution of the terminal amine also influenced the affinity at muscarinic receptors.

New methods for improving the dyeability of cellulose fibres with reactive dyes*

Cellulose fibres may be dyed with reactive dyes in the absence of added electrolyte under neutral to slightly acidic conditions provided the fibre is modified to include cationic sites. The effect of amine substitution has been examined in detail using the activated substrate prepared by the reaction of cotton with N‐methylolacrylamide. Dyes containing pendant aliphatic amino groups were also prepared and their reactivity towards the pre‐activated cotton substrate assessed.

Relaxations in thermosets: 5. Dielectric studies of the effects of substitution of amines on curing kinetics and ageing of an epoxide thermoset

The dielectric permittivity and loss of thermosets of diglycidyl ether of bisphenol A isothermally cured with pure and mixtures of diaminodiphenylmethane (DDM) and diaminodiphenylsulphone (DDS) have been measured as a function of time during their crosslinking process, after their ageing at 298 K for up to 182 days, and after thermal cycling to 453 K for 8 h. During crosslinking, the dielectric properties of thermosets are determined by two effects, namely: (i) a large decrease in the d.c. conduction at the beginning of the cure, and (ii) the dipolar relaxation process later in the cure. As the curing approaches completion, the time dependence of the complex permittivity follows the formalism ø(t)= exp[−( t τ cure ) γ] with γ<0.4. Both the strength of the dipolar relaxation and the value of the curing parameter γ increase with an increase in the amount of DDS in the curing amine. The change in the observed dielectric feature as the molar ratio of DDS in the curing amine mixture is increased are explained semi-quantitatively on the basis of changing kinetics of the crosslinking reactions. Ageing and thermal cycling of cured thermosets cause the strength of both of its sub- T g relaxations to decrease further, as is generally observed for thermoplastics.

The N‐Substitution of Aliphatic Primary Amines via 1‐[(Alkylamino)methyl]benzotriazoles: Preparation of Secondary Amines

AbstractA new method has been developed for the selective conversion of primary aliphatic amines into unsymmetrical secondary amines by Grignard reaction of 1‐[(alkylamino)methyl]‐benzotriazoles 1. This method employs simple procedure and mild conditions, and is specific in that only monoalkylation of the primary amines results.

Base and conformational specificity of an amine modification of DNA.

We have investigated the site and conformational preference of the reaction of a formaldehyde/amine reagent with DNA. Previous investigations of this laboratory have established that this reagent will react with native DNA, placing a positively charged amine moiety on the duplex that will survive exhaustive dialysis. The resulting adduct is duplex and base stacked in character, possessing B backbone geometry with a higher average winding angle and exhibiting remarkable stability with respect to the A-form, Z-form, or the single-strand denaturated species. In this current investigation, we have found that the stability of the adduct is dramatically reduced if the DNA is converted to mononucleotides, thus obviating the usual approach of nuclease digestion and chromatography for the identification of the modified nucleotides. Using indirect approaches, we have established that the reactive site that survives removal of the equilibrium concentrations of CH2O and amine is the exocyclic amino group of the guanine bases. This conclusion is based on (1) the positive correlation between GC content and the extent of adduct formation under standard reaction conditions (27 degrees C, 0.63M CH2O, 0.007M n-butylamine, pH 7); (2) decreases in the level of substitution of amine in DNA, which has this site blocked by trinitrobenzene modification; and (3) failure of poly(dI-dC) to retain amine upon dialysis. Raman spectra of the derivatized poly(dG-dC) show enhanced 2'-endo B character, with no marked shifts in the position of any of the lines, indicating the absence of any ring structures involving the N7 and the 06 of G. In standard reaction mixtures, other sites may react but this phenomenon appears to be minimal under conditions that do not favor fluctuational opening of base pairs. In the latter case, excess loading of amine on high GC content polymers produces a CD spectrum that is similar to one produced by poly(dA-dT) in the "X"-form [M. Vorlickova, E. Minyat, and J. Kypr (1984) Biopolymers 23, 1-4]. This conformation is lost, however, upon removal of excess reagents by dialysis and cannot be reestablished, in the absence of unbound amine and formaldehyde. The reaction is specific for the B-form of polynucleotides as demonstrated by the failure of poly(dG-m5dC) in the stable Z-form to exhibit substantial reaction. The B-form of this polymer will react readily with the retention of 0.23 moles amine/mole nucleotide under our standard reaction conditions.(ABSTRACT TRUNCATED AT 400 WORDS)

Substrate specificity of bleomycin hydrolase

Bleomycin (BLM) hydrolase is believed to protect both malignant and normal tissue from the toxicity of the antitumor drug BLM. Little is known about the substrate specificity of BLM hydrolase. Thus, we developed ion-paired reverse phase high speed liquid chromatography systems to assay for the metabolism of several BLM analogs. We found that BLM A 2, BLM B 2, tallysomycin S 10b (TLM S 10b) peplomycin (PEP), butylamino-3-propylamino-3-propylamine bleomycin (BAPP), deglyco bleomycin A 2 (dgBLM A 2) and bleomycinic acid were each metabolized by rabbit lung BLM hydrolase to a single metabolite. When compared to their corresponding parent compounds, these metabolites were 6- to 35-fold less potent in their ability to inhibit the proliferation of A-253 human head and neck squamous carcinoma cells in culture. Furthermore, we found that substitutions in various regions of the BLM molecule greatly affected the kinetic parameters of BLM hydrolase. For example, the K m with BLM B 2 (0.056 ± 0.005 mM) was 15-fold lower than that seen with BLM A 2 (0.83 ± 0.11 mM). In contrast, the V max was not affected markedly by these terminal amine substitutions but was influenced greatly by deletion of the carbohydrate groups of BLM. For example, a 4-fold higher V max was observed with dgBLM A 2 compared to BLM A 2. Thus, these results demonstrate that BLM hydrolase can recognize and metabolize a broad spectrum of BLM analogs regardless of their structural features. This enzymatic conversion resulted in the inactivation of the BLMs as demonstrated by a substantial decrease in their cytotoxidty. Furthermore, the terminal amine and carbohydrate regions, respectively, dictate the apparent affinity and the rate of metabolism of BLM hydrolase substrates.

Benzothiopyranoindazoles, a new class of chromophore modified anthracenedione anticancer agents. Synthesis and activity against murine leukemias.

The synthesis of the benzothiopyranoindazoles, a new class of chromophore modified anthracenediones related to mitoxantrone, is described. In this structural class the quinone moiety, which is believed to be responsible for the cardiotoxicity of the anthracyclines, has been designed out. The synthesis of the benzothiopyranoindazoles was carried out by a multistep sequence from requisite 1-chloro-4-nitro-9H-thioxanthen-9-one precursors. Reaction with a monoalkylhydrazine gave a 5-nitrobenzothiopyranoindazole adduct, which was catalytically reduced to a corresponding C-5 anilino intermediate. Alkylation of 7 with a requisite X(CH2)nNR1R2 (X = Cl, Br; R1, R2 = H, alkyl, acyl; n = 2,3) provided target "two-armed" benzothiopyranoindazoles or A-ring methoxy and/or side chain acyl intermediates, which could be converted to 3 by appropriate deprotection methodologies. Alternatively, certain target compounds 3 were synthesized by reaction of 7 with appropriately functionalized glycine precursors under Schotten-Bauman or BOP chloride condensation conditions to provide C-5 acylamino intermediates, followed by Red-Al reduction and deprotection steps. Described also is the synthesis of selected benzothiopyranoindazole congeners with proximal acylamino side chains at C-5 and B-ring sulfone functionality at S-6. Potent activity was demonstrated against murine L1210 leukemia in vitro (IC50 = 10(-7)-10(-9) M) as well as against P388 leukemia in vivo over a wide range of structural variants. In general, activity against the P388 line was maximized by (a) a basic side chain at N-2 and a dibasic side chain at C-5 with primary or secondary distal amine substitution, (b) certain patterns of A-ring hydroxylation with 8-OH and 9-OH most favorable, and (c) sulfide oxidation state at S-6. Besides having curative activity against the P388 line, the more active compounds were curative against murine B-16 melanoma in vivo. On the basis of their exceptional broad-spectrum in vivo anticancer activity, selected compounds in this series have been chosen for development toward clinical trials.