Unexpected regiospecific Michael addition product: synthesis of 5,6-dihydrobenzo[1,7]phenanthrolines

Abstract

The unexpected formation of 5,6-dihydrobenzo[1,7]phenanthroline instead of 5,6-dihydrobenzo[1,7]phenanthroline-3-carbonitrile in acridine molecules using Michael addition has been observed for the first time. Moreover, we have identified Montmorillonite KSF clay as a catalyst to obtain regiospecific expected dihydrobenzo[1,7]phenanthroline-3-carbonitrile product and NaH for the regiospecific formation of unexpected Michael addition 5,6-dihydrobenzo[1,7]phenanthroline products. On the basis of a systematic study, the novel regiospecificity could be assigned by the utilization of a suitable catalyst.