One-Pot Tandem 1,3-Dipolar Cycloaddition of Azinium Ylides Using Water as Solvent

Following an important principle of Green Chemistry, namely the use of a benign solvent, the reaction of azines, namely pyridine, isoquinoline and phenanthridine with phenacyl bromides or with t-butyl bromoacetate has been accomplished in water to generate an aqueous solution of the (substituted methyl)azinium bromides, which on further reacting with dimethyl acetylenedicarboxylate (DMAD) and potassium carbonate furnish annelated pyrroles through tandem formation of the azinium methylides followed by 1,3-dipolar cycloaddition. In one case, maleic anhydride could also be used as 1,3-dipolarophile. The products are obtained in good yields and have been well characterized.