Abstract
Effective preparation of cycloheptimidazol-4-ones was developed. The reactions of 2-tosyloxytropone (5) with amidines (6) carried out under simple conditions such as aq. NaOH in toluene at 35 °C afforded the corresponding cycloheptimidazol-4-ones (3) in low yield. However, by adding tetra-n-butylammonium bromide (n-Bu4NBr) to this reaction system, the yield was improved dramatically. The reaction conditions were screened in detail.
