Categories: Synthesis of N-Heterocycles >
Synthesis of 2-imidazolines
Recent Literature
An efficient preparation of 2-imidazolines was achieved from aldehydes and
ethylenediamines in the presence of tert-butyl hypochlorite. By this
method, 1,3-bis(imidazolin-2-yl)benzene and 2,6-bis(imidazolin-2-yl)pyridine,
which act as chiral ligands, could be prepared directly from the corresponding
dialdehydes in high yields.
M. Ishihara, H. Togo, Synthesis, 2007,
1939-1942.
A mild, environmentally friendly, and efficient process enables the synthesis of
2-imidazolines in high yield by reaction of aldehydes with ethylenediamine using
hydrogen peroxide as an oxidant in the presence of sodium iodide and anhydrous
magnesium sulfate.
G.-y. Bai, K. Xu, G.-f. Chen, Y.-h. Yang, T.-y. Li, Synthesis, 2011,
1599-1603.
2-Imidazolines were easily prepared in good yields from the reaction of
aldehydes and ethylenediamine with iodine in the presence of potassium carbonate.
The 2-imidazolines were smoothly oxidized to the corresponding imidazoles in
good yields using (diacetoxyiodo)benzene at room temperature.
M. Ishihara, H. Togo, Synlett,
2006, 227-230.
Various 2-oxazolines were prepared from aromatic aldehydes and 2-aminoethanol
with pyridinium hydrobromide perbromide in water at room temperature. The
reaction of aromatic aldehydes with ethylenediamine gave 2-imidazolines in good
yields under the same reaction conditions.
S. Sayama, Synlett,
2006, 1479-1484.
A one-pot, three-component cascade reaction combining photoredox catalyzed
radical addition and formal [3 + 2] annulation provides imidazoline and
oxazolidine derivatives in very good yields. The advantages of this
transformation are mild reaction conditions, operational simplicity, and easy
accessibility of raw materials.
J.-Q. Chen, W.-L. Yu, Y.-L. Wei, T.-H. Li, P.-F. Xu, J. Org. Chem.,
2017, 82, 243-249.
The use of Cu(OAc)2 as the catalyst in the presence of PhI(OAc)2
and K3PO4 enables an amination of aliphatic C-H bonds of
N-alkylamidines to yield dihydroimidazoles and tetrahydropyrimidines. A
subsequent hydride reduction gives the
corresponding diamines.
H. Chen, S. Synjaya, Y.-F. Wang, S. Chiba, Org. Lett., 2013,
15, 212-215.
A novel cationic Br initiated one-pot synthesis using olefin, nitrile, amine,
and N-bromosuccinimide gives imidazolines in good yields. The olefinic
substrates and the nitrile partners can be flexibly varied to achieve a range of
imidazoline derivatives.
L. Zhou, J. Zhou, C. K. Tan, J. Chen, Y.-Y. Yeung, Org. Lett., 2011,
13, 2448-2451.
A mild reaction of α,α-difluoroalkyl amines with β-amino alcohols, β-amino thiols, and β-diamines
affords the
corresponding oxazoline, thiazoline, and imidazoline derivatives, respectively. The
conditions are
applicable for the synthesis of optically active heterocyclic compounds.
T. Fukuhara, C. Hasegawa, S. Hara, Synthesis, 2007,
1528-1534.
A palladium-catalyzed cyclization of 2,3-allenyl amines with aryl iodides
provides polysubstituted 2-imidazoline derivatives in good yields via formation
of new carbon-carbon and carbon-nitrogen bonds in a single synthetic operation.
Y. Liu, C. Zhang, X. Liang, X. Zeng, R. Lu, Z. Fang, S. Wang, Y. Liu, J. Hu, Synthesis, 2020, 52,
901-908.
A novel electrophilic one-pot reaction of an olefin, a cyanimide, an
amine, and N-bromosuccinimide enables the synthesis of a number of
guanidine derivatives with very good yields - including an rTRTVI precursor.
L. Zhou, J. Chen, J. Zhou, Y.-Y. Yeung, Org. Lett., 2011,
13, 5804-5807.
The key step in a new route for the construction of 2-aminoimidazolidines is an
intramolecular microwave-assisted Staudinger/aza-Wittig cyclization of an in
situ generated urea intermediate upon treatment with Bu3P or
polymer-supported phosphine reagent. Furthermore, a useful one-pot Staudinger/aza-Wittig/Buchwald-Hartwig
protocol leading to bicyclic guanidines has been elaborated.
R. Kumar, D. S. Ermolat'ev, E. V. Van der Eycken, J. Org. Chem., 2013,
78, 5737-5743.
Reaction of iodoethanol with aniline provides N-(2-iodoethyl)arylamine
salts that are then converted to the corresponding iodide. A subsequent reaction
with aliphatic or aromatic amines followed by triethyl orthoformate gave 26
different NHC ligands.
B. A. B. Prasad, S. R. Gilbertson, Org. Lett., 2009,
11, 3710-3713.
The reaction of formamidines and (2-bromoethyl)diphenylsulfonium triflate
enables the synthesis of various symmetrical and unsymmetrical imidazolinium
triflate salts in high yield in short reaction times under mild conditions.
Aromatic and aliphatic N-substituents work well. The reaction is proposed to
proceed via generation of a vinyl sulfonium salt intermediate from the
bromoethylsulfonium triflate.
E. M. McGarrigle, S. P. Fritz, L. Favereau, M. Yar, V. K. Aggarwal, Org. Lett., 2011,
13, 3060-3063.
A very simple and efficient, microwave-assisted procedure is reported for the
synthesis of 1,3-diarylimidazolinium chlorides by cyclization of N,N′-diarylethylenediamines
dihydrochlorides with triethyl orthoformate.
A. Aidouni, A. Demonceau, L. Delaude, Synlett,
2006, 493-495.