DEVELOPMENT OF HIGHLY CHEMOSELECTIVE DEPROTONATION USING ZINCATES

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As a new chemoselective deprotonative agent, TMP-zincate was designed. The agent was found to be easily prepared using LTMP and di-tert-butylzinc. The agent is stable ate complex and can be used for the selective metalation of functionalized aromatic compounds with electrophilic groups. Various electrophiles were reacted with the arylzincates prepared by this deprotonation, and the scope and limitation of the methodology was disclosed. The reaction was successfully applied for the deprotonation of heteroaromatic compounds such as pyridines, isoquinolines, quinolines, and other nitrogen heteroaromatics. On the metalation of substituted pyridines, unique regioselectivity was observed and a-metalation predominates when 2-halopyridines were employed for substrates. Further investigations on the origin of this regioselectivity are underway. Application of the deprotonation for solid phase synthesis was also investigated, and the possibility was examined although further optimization of reaction conditions are necessary. Relating the deprotonation, mesityllithium was found to be an another option for selective deprotonation on polymer support, and the investigation for the scope and limitation are underway.