Diazines 13: Metalation without Ortho-Directing Group - Functionalization of Diazines via Direct Metalation
摘要:
The successful metalation of diazines without an ortho-directing group is described. In some cases, dimers were obtained. The metalation was optimal with LTMP if a 4-fold excess of metalating agent was used, with a very short metalation reaction time at -75 degrees C. This procedure was applied to pyrimidine, 2-substituted pyrimidines, pyridazine, and pyrazine, allowing for the synthesis of various monosubstituted diazines.
We report herein the ‘metal-halogen exchange’ reaction in the diazine series with lithium tri-n-tributylmagnesate. The reaction was performed with 2-iodopyrazine, 2-methylsulfanyl-4-iodopyrimidine and 3-iodo-6-phenylpyridazine. Benzophenone, aldehydes and diphenylsulfur were used as electrophiles affording alcohols and phenylsulfanyl derivatives with satisfactory to good yields.