Electrophilic Substitution and Nucleophilic Addition of 3,4-Dihydro-5(1H)-pyrromethenones

Article abstract of DOI:10.1007/BF00809213

3,4-Dihydro-5(1H)-pyrromethenones are easier attacked at the meso-position by electrophiles than 5(1H)-pyrromethenones.This is demonstrated both by a Mannich-type-substitution or deuterium-exchange-experiments and by the addition of O-, S-, and N-Nucleophiles to the exocyclic double bond of the model-dihydropyrromethenone (Z)-1 under very mild reaction conditions.Applying these results to the chemistry of 2,3-dihydro-bilatrienes-abc, their chemical characteristics - especially their tautomeric behaviour and their dominant C-5-selectivity towards electrophiles - become better understandable. - Keywords: 3,4-Dihydro-5(1H)-pyrromethenones; 5(1H)-Pyrromethenones; 2,3-Dihydro-bilatrienes-abc; Electrophilic substitution; Nucleophilic addition