Efficient One-Pot Multicomponent Approach to 3-Phenylpyrrolo[1,2-a]Pyrazine and Novel 3-Phenylpyrazino[1,2-a]Indole in Aqueous Medium

A facile and atom-efficient route via a new aqueous synthetic protocol for the greener and more efficient preparation of 3-phenylpyrrolo[1,2-a]pyrazine and 3-phenylpyrazino[1,2-a]indole by the one-pot, three-component method under mild reaction conditions is developed with substituted phenacyl bromides, aqueous ammonium hydroxide, and the corresponding 1H-pyrrole-2-carbaldehyde and 1H-indole-2-carbaldehyde. A reaction cascade consisting of N-alkylation, imine formation, and annulation by condensation produces a sequence of three C-N bonds.