New dihydrofuran and dihydropyran derivatives by iodoenolcyclization of 2-prenyl-1,3-dicarbonyl compounds: Studies on the regiochemistry

Both dihydrofuran and dihydropyran derivatives are obtained performing iodoenolcyclization of 2-alkenyl-1,3-dicarbonyl compounds having a highly substituted double bond. The regiochemistry is greatly dependent on the nature of carbonyl groups.