Facile Regioselective Synthesis of Pyrrolo-Pyrones: Tandem Reaction of 4- N-(4' -Aryloxy-2' -ynyl), N-Methyl Pyran-2-Ones with 3-Chloroperoxybenzoic Acid (Experimental Section)

A number of 6-methyl-4-N-(4'-aryloxybut-2'-ynyl)-N-methylaminopyran-2-ones (3a-g) on treatment with one equivalent of 3-chloroperoxybenzoic acid at 0-5 C during 25 minutes and then stirring at room temperature for 9 h afforded pyrrolo[3,2-c]pyrone derivatives (4a-g) in (80-85 %) yield. 6-Methyl-4-N-(4'- aryloxybut-2'-ynyl)N-methylaminopyran-2-ones (3a-g) were in turn prepared from 4-tosyloxy-6-methylpyran- 2-ones (1) and N-(4-aryloxybut-2-ynyl)- N-methylamine (2a-g).