Categories: Synthesis of N-Heterocycles >
Synthesis of hydantoins
A simple reaction of α-amino methyl ester hydrochlorides with carbamates provides 3-substituted, 5-substituted, or 3,5-disubstituted hydantoins in good yields via ureido derivatives, which subsequently cyclize under basic conditions. The process avoids conventional multistep protocols and does not use hazardous, irritant, toxic, or moisture-sensitive reagents, such as isocyanates or chloroformates.
D. K. Tanwar, A. Ratan, M. S. Gill, Synlett, 2017, 28, 2285-2290.
The synthesis of highly substituted chiral hydantoins from simple dipeptides proceeded through the dual activation of an amide and a tert-butyloxycarbonyl (Boc) protecting group by Tf2O-pyridine under mild conditions in a single step. This method was successfully applied in the preparation of various biologically active compounds, including drug analogs and natural products.
H. Liu, Z. Yang, Z. Pan, Org. Lett., 2014, 16, 5902-5905.
Reaction of carbodiimides with α-Br(Cl)-aryl acetic acids produces N,N′-substituted 5-arylhydantoins under very mild conditions and high yields. When the carbodiimides are generated in situ by Staudinger reaction, the process becomes a one-pot, three-component sequential synthesis of libraries of differently substituted 5-arylhydantoins.
F. Olimpieri, A. Volonterio, M. Zanda, Synlett, 2008, 3016-3020.
1,5-Disubstituted hydantoins/thiohydantoins have been synthesized in good yield by a microwave-promoted solvent-free condensation of arylglyoxals and phenylurea/thiourea using polyphosphoric ester (PPE) as a reaction mediator. The workup is simple and involves treatment with ice-cold water.
S. Paul, M. Gupta, R. Gupta, A. Loupy, Synthesis, 2002, 75-78.
Enantiomerically pure hydantoins are prepared from optically pure α-amino amides utilizing triphosgene. A mechanism for the racemization observed with 1,1'-carbonyldiimidazole (CDI) for this type of reaction is proposed.
D. Zhang, X. Xing, G. D. Cuny, J. Org. Chem., 2006, 71, 1750-1753.
A novel intermolecular α-amination process of esters using CuCl as catalyst and di-tert-butyldiaziridinone as nitrogen source forms hydantoins effectively under mild reaction conditions.
B. Zhao, H. Du, Y. Shi, J. Am. Chem. Soc., 2008, 130, 7220-7221.
F. Fernández-Nieto, J. M. Roselló, S. Lenoir, S. Hardy, J. Clayden, Org. Lett., 2015, 17, 3838-3841.
Palladium(II) trifluoroacetate catalyzes the C-arylation of N,N-disubstituted hydantoins by aryl iodides in good yield. The reaction is successful with various hydantoins and a range of electron-rich and electron-poor aryl iodides.
Formation of iminophosphoranes in a Staudinger reaction and condensation with carbon disulfide followed by condensation with α-amino esters provides N-3-substituted 2-thiohydantoins.
S. Gosling, C. El Amri, A. Tatibouët, Synthesis, 2014, 46, 1079-1084.