Psychoactive Plant Database - Neuroactive Phytochemical Collection

1. Org Biomol Chem. 2016 Jan 28;14(4):1421-7. doi: 10.1039/c5ob02128f. Epub 2015 
Dec 16.

Reaction mechanisms in ionic liquids: the kinetics and mechanism of the reaction 
of O,O-diethyl (2,4-dinitrophenyl) phosphate triester with secondary alicyclic 
amines.

Pavez P(1), Millán D, Morales J, Rojas M, Céspedes D, Santos JG.

Author information:
(1)Facultad de Química. Pontificia Universidad Católica de Chile, Casilla 306, 
Santiago 6094411, Chile. ppavezg@uc.cl.

Erratum in
    Org Biomol Chem. 2016 Jan 28;14(4):1502. doi: 10.1039/c5ob90208h.

The reactions of O,O-diethyl 2,4-dinitrophenyl phosphate triester (1) with 
secondary alicyclic (SA) amines in the ionic liquids [Bmim]BF4 and [Bmim]DCA 
were subjected to a kinetic study. Eyring plots were obtained for the title 
reactions in the above ionic liquids (ILs) and also in aqueous ethanol (44 wt% 
ethanol). Two different reaction pathways were observed in [Bmim]BF4: 
nucleophilic attack at the phosphoryl center, SN2(P), and at the C-1 aromatic 
carbon, SN(Ar), where the product distribution remained constant and independent 
of the amine nature. In contrast, in [Bmim]DCA only the SN2(P) pathway was 
found. From the kinetic analysis of the SN2(P) pathway in both ILs, curved 
upwards plots of kobsdvs. 1-formylpiperazine concentration were obtained. Based 
on the kinetic behavior, a change in the mechanism of the SN2(P) pathway is 
proposed for the aminolysis of 1, from a concerted process in aqueous ethanol to 
a stepwise mechanism, through a zwitterionic pentacoordinate intermediate, when 
[Bmim]BF4 and [Bmim]DCA are used as the solvents of the reaction.

DOI: 10.1039/c5ob02128f
PMID: 26676671


2. Spectrochim Acta A Mol Biomol Spectrosc. 2014 Jan 24;118:1113-20. doi: 
10.1016/j.saa.2013.09.095. Epub 2013 Oct 8.

Infrared and Raman spectra, conformational stability and vibrational assignment 
of 1-formylpiperazine.

Keşan G(1), Parlak C.

Author information:
(1)Institute of Physics and Biophysics, Faculty of Science, University of South 
Bohemia, Branišovská 31, České Budějovice 370 05, Czech Republic.

Infrared and Raman spectra of 1-formylpiperazine (1-fp) have been recorded in 
the region of 4000-50 cm(-1). The conformational analysis, optimized geometric 
parameters, normal mode frequencies and corresponding vibrational assignments of 
1-fp (C5H10N2O) have been examined by means of Becke-3-Lee-Yang-Parr (B3LYP) 
density functional theory (DFT) method together with 6-31++G(d,p) basis set. 
Furthermore, reliable conformational investigation and vibrational assignments 
have been made by the potential energy surface (PES) and potential energy 
distribution (PED) analyses, respectively. Calculations are carried out with the 
possible six conformational isomers of 1-fp, both in gas phase and in solution 
using benzene and methanol. The experimental and theoretical results indicate 
that B3LYP method provides satisfactory evidence for the prediction vibrational 
wavenumbers, and the normal chair conformation with equatorial substituents is 
not preferred due to the steric interaction.

Copyright © 2013 Elsevier B.V. All rights reserved.

DOI: 10.1016/j.saa.2013.09.095
PMID: 24161874 [Indexed for MEDLINE]


3. Org Biomol Chem. 2006 Aug 21;4(16):3155-65. doi: 10.1039/b605458g. Epub 2006
Jul  18.

Intramolecular 1,3-dipolar cycloadditions of dihydroimidazolium ylides: 
synthesis of pyrrolo[1,2,3-de]quinoxalines and imidazo[1,2-a]indoles.

Lory PM(1), Jones RC, Iley JN, Coles SJ, Hursthouse MB.

Author information:
(1)Chemistry Department, The Open University, Walton Hall, Milton Keynes, UK.

N-Alkylation of 4,5-dihydroimidazoles with alkene-containing bromomethyl ketones 
and treatment of the so-formed 4,5-dihydroimidazolium ions with DBU gives rise 
to an intramolecular 1,3-dipolar cycloaddition reaction that affords (via a 
reaction cascade involving eliminative ring-opening, recyclisation and 
prototropic tautomerism) unexpected hexahydropyrrolo[1,2,3-de]quinoxaline 
products. Steric bulk in both the dihydroimidazole and the dipolarophile allows 
isolation of an imidazo[1,2-a]indole, the initial product of cycloaddition. When 
the bromomethyl ketone contains no other functionality, or when cycloaddition is 
inhibited due to steric constraints, the dihydroimidazolium ion undergoes 
ring-opening hydrolysis followed by recyclization of the exposed amino ketone to 
afford either 3-alkyl-1-formylpiperazine-2-ones or 
3-aryl-1-formyl-1,4,5,6-tetrahydropyrazines.

DOI: 10.1039/b605458g
PMID: 16886085


4. J Org Chem. 2002 Jun 14;67(12):4309-15. doi: 10.1021/jo025562a.

Kinetic and mechanistic investigation of the aminolysis of 3-methoxyphenyl 
3-nitrophenyl thionocarbonate, 3-chlorophenyl 3-nitrophenyl thionocarbonate, and 
bis(3-nitrophenyl) thionocarbonate.

Castro EA(1), Galvez A, Leandro L, Santos JG.

Author information:
(1)Facultad de Química, Pontificia Universidad Católica de Chile, Casilla 306, 
Santiago 22, Chile. ecastro@puc.cl

The reactions of the title thionocarbonates (6, 7, and 8, respectively) with a 
series of secondary alicyclic amines are subjected to a kinetic investigation in 
44 wt % ethanol-water, 25.0 degrees C, ionic strength 0.2 M (KCl). Under excess 
amine, pseudo-first-order rate coefficients (k(obsd)) are obtained for all 
reactions. Reactions of substrates 6 and 7 with piperidine and of 
thionocarbonate 8 with the same amine and piperazine, 
1-(2-hydroxyethyl)piperazine, and morpholine show linear k(obsd) vs [amine] 
plots, with slopes (k(1)) independent of pH. On the other hand, these plots are 
nonlinear upward for the reactions of substrates 6 and 7 with all the amines, 
except piperidine, and also for the reactions of compound 8 with 
1-formylpiperazine and piperazinium ion. For all these reactions a mechanistic 
scheme is proposed with the formation of a zwitterionic tetrahedral intermediate 
(T(+/-)), which can transfer a proton to an amine to give an anionic 
intermediate (T(-)). Rate and equilibrium microcoefficients of this scheme, 
k(1), k(-)(1), K(1) (= k(1)/k(-)(1)), and k(2), are obtained by fitting the 
nonlinear plots through an equation derived from the scheme. The Brönsted-type 
plots for k(1) are linear with slopes beta(1) = 0.19, 0.21, and 0.26 for the 
aminolysis of 6, 7, and 8, respectively. This is consistent with the hypothesis 
that the formation of T(+/-) (k(1) step) is the rate-determining step. The k(1) 
values for these reactions follow the sequence 8 > 7 > 6, consistent with the 
sequence of the electron-withdrawing effects from the substituents on the 
"nonleaving" group of the substrates. The k(1) values for the aminolysis of 6, 
7, and 8 are smaller than those for the same aminolysis of 3-methoxyphenyl, 
3-chlorophenyl, and 4-cyanophenyl 4-nitrophenyl thionocarbonates (2, 3, and 4, 
respectively). The k(2) values (expulsion of the nucleofuge from T(+/-)) 
increase as the electron withdrawal from the nonleaving group increases. These 
values are smaller for the aminolysis of 6, 7, and 8 compared to those for the 
same aminolysis of 2, 3, and 4, respectively.

DOI: 10.1021/jo025562a
PMID: 12054968


5. J Org Chem. 2001 Sep 7;66(18):6130-5. doi: 10.1021/jo0157371.

Kinetics and mechanisms of the reactions of 3-methoxyphenyl, 3-chlorophenyl, and 
4-cyanophenyl 4-nitrophenyl thionocarbonates with alicyclic amines.

Castro EA(1), Leandro L, Quesieh N, Santos JG.

Author information:
(1)Facultad de Química, Pontificia Universidad Católica de Chile, Casilla 306, 
Santiago 22, Chile. ecastro@puc.cl

The reactions of 3-methoxyphenyl, 3-chlorophenyl, and 4-cyanophenyl 
4-nitrophenyl thionocarbonates (1, 2, and 3, respectively) with a series of 
secondary alicyclic amines are studied kinetically in 44 wt % ethanol-water at 
25.0 degrees C and an ionic strength of 0.2 M (KCl). Pseudo-first-order rate 
coefficients (k(obsd)) are obtained for all reactions (amine excess was used). 
The reactions of compound 1 with piperidine, piperazine, and 
1-(2-hydroxyethyl)piperazine and of compounds 2 and 3 with these amines and 
morpholine exhibit linear k(obsd) versus amine concentration plots with slopes 
(k1) independent of pH. In contrast, the plots are nonlinear upward for the 
reactions of substrate 1 with morpholine, 1-formylpiperazine, and piperazinium 
ion and of substrates 2 and 3 with the two latter amines. For all these 
reactions, a reaction scheme is proposed with a zwitterionic tetrahedral 
intermediate (T+/-), which can be deprotonated by an amine to yield an anionic 
intermediate (T-). When the nonlinear plots are fit through an equation derived 
from the scheme, rate and equilibrium microcoefficients are obtained. The 
Brönsted-type plots for k1 are linear with slopes of beta1 = 0.22, 0.20, and 
0.24 for the aminolysis of 1, 2, and 3, respectively, indicating that the 
formation of T+/- (k1 step) is rate-determining. The k1 values for these 
reactions follow the sequence 3 > 2 > 1, which can be explained by the sequence 
of the electron-withdrawing effects from the substituents on the nonleaving 
group of the substrates.

DOI: 10.1021/jo0157371
PMID: 11529741