SYNTHESIS OF 1-(DIMETHYLSULFAMOYL)-2-5-IMIDAZOLECARBOXALDEHYDE AND 1-(DIMETHYLSULFAMOYL)-2-LECARBOXALDEHYDES - REARRANGEMENT OF 1-(DIMETHYLSULFAMOYL)-5-IMIDAZOLE-CARBOXALDEHYDE TO THE 4-CARBOXALDEHYDE

Lithiation of 1-(dimethylsulfamoyl)imidazole by n-butyllithium, follow ed by substitution with dimethylformamide provided 1-(dimethylsulfamoy l)-2-imidazolecarboxaldehyde in 19% yield. When hylsulfamoyl)-2-(tert- butyldimethylsilyl)imidazole was lithiated by sec-hutyllithium, follow ed by methyl formate, there was obtained tert-butyldimethylsilyl)-5-im idazolecarboxaldehyde (57%). Removal of the silyl group by acetic acid yielded 1-(dimethylsulfamoyl)-5-imidazolecarboxaldehyde (11, 96%) as a gum. Isomerization of 11 took place slowly at room temperature (10 d ays), or faster in tetrahydrofuran solution containing triethylamine ( 2 hours) to form crystalline 1-(dimethylsulfamoyl)-4-imidazolecarboxal dehyde (12) in 68% yield. Proton and carbon-13 nmr spectra were analyz ed to determine the structure of the isomers. However, only X-ray,crys tallography established the structure of 1-(dimethylsulfamoyl)-4-imida zolecarboxaldehyde unequivocally. A mechanism for the isomerization of 11 to 12 is proposed.