Synthesis of 1‐(dimethylsulfamoyl)‐2‐ and 5‐imidazolecarboxaldehydes. Rearrangement of 1‐(dimethylsulfamoyl)‐5‐imidazole‐carboxaldehyde to the 4‐carboxaldehyde
- 1 March 1995
- journal article
- research article
- Published by Wiley in Journal of Heterocyclic Chemistry
- Vol. 32 (2) , 611-620
- https://doi.org/10.1002/jhet.5570320241
Abstract
Lithiation of 1‐(dimethylsulfamoyl)imidazole by n‐butyllithium, followed by substitution with dimethylformamide provided 1‐(dimethylsulfamoyl)‐2‐imidazolecarboxaldehyde in 19% yield. When 1‐(dimethylsulfamoyl)‐2‐(tert‐butyldimethylsilyl)imidazole was lithiated by sec‐butyllithium, followed by methyl formate, there was obtained 1‐(dimethylsulfamoyl)‐2‐(tert‐butyldimethylsilyl)‐5‐imidazolecarbox‐aldehyde (57%). Removal of the silyl group by acetic acid yielded 1‐(dimethylsulfamoyl)‐5‐imidazolecarbxaldehyde (11, 96%) as a gum. Isomerization of 11 took place slowly at room temperature (10 days), or faster in tetrahydrofuran solution containing triethylamine (2 hours) to form crystalline 1‐(dimethylsul‐famoyl)‐4‐imidazolecarboxaldehyde (12) in 68% yield. Proton and carbon‐13 nmr spectra were analyzed to determine the structure of the isomers. However, only X‐ray crystallography established the structure of 1‐(dimethylsulfamoyl)‐4‐imidazolecarboxaldehyde, unequivocally. A mechanism for the isomerization of 11 to 12 is proposed.Keywords
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