a facile and highly efficient three component synthesis of pyran and chromene derivatives in the presence of nano sno2 as a catalyst

nano tin dioxide was employed as a catalyst for efficient and facile preparation of pyran derivatives via the one-pot three component condensation reaction of various aldehydes with malononitrile and dimedone. chromene derivatives via the one-pot three component condensation reaction of various aldehyde with malononitrile and 4-hydroxycoumarin were also synthesized by this novel catalyst. the described novel synthesis method proposes several advantages of mild condition, safety, high yields, short reaction times compared to the traditional method of synthesis.