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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 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.

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.