Chiral Imidazolidinones

Chiral Imidazolidinones

Imidazolidinone, an organic compound with a molecular formula of C₃H₆N₂O, is a colorless needle crystal, which is generally divided into 2-imidazolidinone and 4-imidazolidinone. As an important member of the imidazole series of compounds, imidazolidinone has attracted more and more attention because of its wide application in the fields of medicine, chemical industry, and biology.

Figure 1. 2-imidazolidinone

Applications

Imidazolidinones can be used in a variety of catalytic reactions, of which the most common is Diels-Alder reactions, such as the asymmetric Diels-Alder reaction of cyclopentadiene with cinnamaldehyde. It can also be used for asymmetric cycloaddition, asymmetric alkylation, and the like.

Production

• Ammonium carbonate method: Some scholars have carefully studied the results of predecessors, and proposed a method for synthesizing imidazolidinone with ethylene carbonate as raw material and ethylene glycol, ethylenediamine and ethylene oxide. It should be noted that in this method, the raw material ammonium carbonate is so unstable that it can be easily decomposed in the air.

  Figure 2. Synthesis of imidazolidinone from ethylene carbonate and ethylenediamine.

• Carbon dioxide method: Some scholars have used carbon dioxide and diamine or amino alcohol compounds to synthesize ring veins. In the absence of a catalyst, the authors reacted with ethylenediamine and carbon dioxide at 7 MPa and 100℃ to obtainimidazolidinone in 97% yield.

  Figure 3. Synthesis of imidazolidinone from dioxide and ethylenediamine.

• Urea method: For the first time in 1949, the use of urea and ethylenediamine as raw materials to synthesize 2-imidazolidinone was reported. The scientists then improved the reaction. In 2004, some scholars used ZnO as a catalyst and DMF as a solvent to react ethylenediamine or ethanolamine with urea to obtain 2-imidazolidinone, which obtained 95% yield. Under the same conditions, the final product of aminoethanol and urea is mainly 2-oxazolidinone, the yield of which is up to 90%, and the yield of 2-imidazolidinone is less than 10%.

  Figure 4. Synthesis imidazolidone under microwave irradiation

• Phosgene method: It is also possible to synthesize imidazolidinone by cyclization condensation reaction with phosgene and ethylenediamine. However, phosgene as a highly toxic and high-risk raw material should be avoided as much as possible under the current requirements of green chemistry.

  Figure 5. Synthesis imidazolidone from phosgene and ethylenediamine

• Solvent-free method: The imidazolidinone is synthesized in one step by ring formation of ethylenediamine and urea at a high temperature in the absence of a solvent.

  Figure 6. Solvent-free synthesis of the imidazolidinone

References

1. Liutang Wang, Bin Zhang, Jianxin J. (2009).“Synthesis and evaluation of structurally constrained imidazolidine derivatives as potent dipeptidyl peptidase IV inhibitors”. Eur. J. Med. Chem. 44:3318-3322
2. Maria das Dores M.C. Ribeiro da Silva. (2008).”Enthalpies of formation of imidazolidine-2-one and N, N-trimethyleneurea.” J. Chem. Thermodyn. 40: 386-393