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Synthesis of 1‐(dimethylsulfamoyl)‐2‐ and 5‐imidazolecarboxaldehydes. Rearrangement of 1‐(dimethylsulfamoyl)‐5‐imidazole‐carboxaldehyde to the 4‐carboxaldehyde
Author(s) -
Kim JangWoo,
Abdelaal Salma M.,
Bauer Ludwig,
Heimer Norman E.
Publication year - 1995
Publication title -
journal of heterocyclic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.321
H-Index - 59
eISSN - 1943-5193
pISSN - 0022-152X
DOI - 10.1002/jhet.5570320241
Subject(s) - chemistry , imidazole , isomerization , triethylamine , tetrahydrofuran , acetic acid , yield (engineering) , aldehyde , butyllithium , dimethylformamide , medicinal chemistry , methyl formate , silylation , stereochemistry , organic chemistry , methanol , catalysis , solvent , materials science , metallurgy
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.