617-92-5Relevant articles and documents
An efficient synthesis of tertiary amines from nitriles in aprotic solvents
Shares, Jonathan,Yehl, Jenna,Kowalsick, Amanda,Byers, Philip,Haaf, Michael P.
scheme or table, p. 4426 - 4428 (2012/09/25)
Tertiary amines are utilized extensively as non-nucleophilic proton scavengers for a number of organic transformations. Herein we report the efficient syntheses of tertiary alkyl amines from their corresponding alkyl nitriles in the presence of a heterogeneous palladium catalyst and a source of dihydrogen in aprotic solvents. The reaction is atom economic, the conditions are mild, and the isolated yields are virtually quantitative. The degree of amine alkylation shows some solvent dependency; in polar protic solvents such as ethanol or methanol, the reaction affords a mixture of products with the secondary alkyl amine as the major product.
Synthesis and structure-activity relationships of aroylpyrrole alkylamide bradykinin (B2) antagonists
Youngman, Mark A.,Carson, John R.,Lee, Jung S.,Dax, Scott L.,Zhang, Sui-Po,Colburn, Ray W.,Stone, Dennis J.,Codd, Ellen E.,Jetter, Michele C.
, p. 1341 - 1344 (2007/10/03)
The synthesis and structure-activity relationships of a novel series of aroylpyrrole alkylamides as potent selective bradykinin B2 receptor antagonists are described. Several members of this series display nanomolar affinity at the B2 receptor and show activity in an animal model of antinociception.
Influence of the reaction temperature on the regioselectivity in the rhodium-catalyzed hydroformylation of vinylpyrroles
Caiazzo, Aldo,Settambolo, Roberta,Uccello-Barretta, Gloria,Lazzaroni, Raffaello
, p. 279 - 284 (2007/10/03)
The influence of the temperature on the regioselectivity in the hydroformylation of the vinylpyrrole isomers and of the corresponding N-tosylated substrates has been investigated in the range 20-100°C, in the presence of Rh4(CO)12. At all the temperatures the branched aldehyde was prevailing with respect to the linear isomer for all the substrates ( α-regioselectivity). With increasing temperature, an increase of the linear aldehyde was observed to a different extent in dependence on the substrate nature. 2H NMR investigation of the crude reaction mixture recovered from deuterioformylation of 3-vinylpyrrole at partial substrate conversion points out that the observed depression of the α-regioselectivity with increasing temperature must be connected to a β-hydride elimination process occurring for the branched alkyl-rhodium intermediates but not for the linear ones.
Selective Alkylation of Pyrrole by Phase Transfer Catalysis in the Absence of Solvent
Diez-Barra, E.,Hoz, A. de la,Loupy, A.,Sanchez-Migallon, A.
, p. 1715 - 1718 (2007/10/02)
Selective N-alkylation of pyrrole is performed, in good yield and by a very simple method, using Phase Transfer Catalysis in the absence of solvent.
Homolysis in the Reaction of Grignard Reagents. II. The Reaction of Pyridazine
Holm, Torkil
, p. 279 - 283 (2007/10/02)
Pyridazine reacts with Grignard reagents by a homolytic mechanism as seen the presence of N-alkylated dimers, dialkyl- and trialkyl-pyrroles as well as other 'radical-type' compounds in the reaction product.The non-alkylated product 1,4-dihydropyridazine was also found.The kinetics of the reaction indicate high reactivity of tertiary and secondary reagents and low reactivity of methylmagnesium bromide as expected for a homolytic reaction.
Gas-phase heteroaromatic substitution. 8. Electrophilic attack of ethyl cation on pyrrole, N-methylpyrrole, furan, and thiophene
Laguzzi,Bucci,Grandinetti,Speranza
, p. 3064 - 3068 (2007/10/02)
Ethyl cation, obtained in the dilute gas state, together with CH5+, from the γ-radiolysis of methane, has been allowed to react with pyrrole, N-methylpyrrole, furan, and thiophene, in the pressure range 50-760 Torr and in the presence of variable concentrations of a gaseous base (NMe3). The mechanism of the substitution and of the subsequent isomerization of the relevant ionic intermediates is discussed, and the intrinsic positional selectivity of the C2H5+ ions is evaluated. Gas-phase C2H5+ ion attack on pyrroles is characterized by a significant positional selectivity toward those substrate positions with the highest net negative charge (N:α:β = 13%:10%:77% for pyrrole; α:β = 19%:81% for N-methylpyrrole). Interaction of C2H5+ with the furan center having the maximum value of the negative charge, i.e. the O atom, favors occurrence of α-substitution (α:β = 57%:43%). Thiophene displays no significant positional discrimination (α:β = 54%:46%). Gas-phase attack of C2H5+ on simple five-membered heteroaromatics is mainly governed by electrostatic interactions established within the encounter pair. This characterizes gaseous C2H5+ as a very ''hard'' electrophile, rather than a borderline acid, as expected on the grounds of the alkyl cation ''hardness'' scale. This deviation is explained in terms of the bridged geometry for C2H5+ and its effect on the LUMO energy level of the ion.
- and pyrroles as Thromboxane Synthetase Inhibitors
Martinez, Gregory R.,Walker, Keith A. M.,Hirschfeld, Donald R.,Maloney, Patrick J.,Yang, Diana S.,Rosenkranz, Roberto P.
, p. 890 - 897 (2007/10/02)
Several and pyrroles were prepared and evaluated in vitro as thromboxane synthetase inhibitors in human platelet aggregation studies.A number of structures, e.g. 10b,f,g,i (respective IC50 values: 1 μM, 50 nM, 42 nM, 44 nM) showed superior in vitro inhibition of TXA2 synthetase when compared to the standard dazoxiben (1).However, it was found that in vitro potency did not translate into nor correlate with in vivo activity when these compounds were evaluated in mice in a collagen-epinephrine-induced pulmonary thromboembolism model. (E)-1-Methyl-2--5-(2-carboxyprop-1-enyl)pyrrole (10b) was found to offer protection against collagen-epinephrine-induced mortality in mice, thereby demonstrating that oral administration is an effective route for absorption of this drug.Additional evidence for the oral effectiveness of 10b in lowering serum TXB2 levels was obtained by performing ex vivo radioimmunoassay experiments with rats.A 13-week study of 10b in rats with reduced renal mass was conducted in order to evaluate the role of TXA2 production in hypertension and renal dysfunction.Although serum and urinary TXB2 levels in rats were found to be lowered during this study by 10b, the levels of urinary protein excretion remained comparable to that of the control group.
PHASE TRANSFER CATALYSIS WITHOUT SOLVENT. USE OF ALKYL IODIDES.
Diez-Barra, E.,Hoz, A. de la,Sanchez-Migallon, A.,Sanchez-Verdu, P.,Bram, G.,et al.
, p. 293 - 296 (2007/10/02)
The Phase Transfer Catalysis (PTS) without solvent method allows the use of quaternary ammonium salts (QAS) when alkyl iodides are used.
Thermolysis of Polyazapentadienes. Part 8. The formation of Pyrroles from 1,1-Dialkyl-5-aryl-1,5-diazapentadienes
McNab, Hamish,Murray, M. Elizabeth-Ann
, p. 333 - 338 (2007/10/02)
Flash vacuum pyrolysis of the 1,5-diazapentadienes (4)-(10) gave moderate yields of pyrroles together with quinolines, formed by electrocyclic ring closure with elimination.The pyrroles were formed by hydrogen transfer from an N-alkyl group, followed by cyclisation and final aromatisation of the resulting dihydropyrrole intermediate by free-radical cleavage.The mechanism of the hydrogen transfer and cyclisation is not known with certainty, but may involve diradicals or 1,5-dipolar intermediates.
Thermolysis of Polyazapentadienes. Part 9. Gas Phase Thermolysis of Some Dienamines, Enaminones, and Enaminothiones
Hickson, Clare L.,McNab, Hamish
, p. 339 - 342 (2007/10/02)
Thermolysis of the title compounds gives low yields of pyrroles by hydrogen-transfer-cyclisation-aromatisation sequence.The results are best explained by a dipolar mechanism for the hydrogen-transfer step: competitive aromatisation routes account for the range of substituted pyrroles which were obtained.
