Decarboxylative, Diastereoselective and exo-Selective 1,3-Dipolar Cycloaddition for Diversity-Oriented Construction of Structural Spiro[Butyrolactone–Pyrrolidine–Chromanone] Hybrids

Inspired by the chemistry and biology of butyrolactones, pyrrolidines and chromanones, herein we successfully developed a simple domino 1,3-dipolar cycloaddition of homoserine lactone-derived azomethine ylides for construction of biologically important spiro-[butyrolactone-pyrrolidine-chromanone] hybrids in the presence of the catalyst Et3N under mild conditions. It is based on the application of carboxylic acid activated chromones as dienophiles followed by a decarboxylation process. This reaction displayed good substrate tolerance and gave the desired products in moderate to good yields with high diastereoselectivities via an exo-transition state (up to 85% yield and >20:1 diastereomeric ratio). In particular, this is the first example of introduction of chromanone moiety into spiro [butyrolactone-pyrrolidine] frameworks, which might be valuable in medicinal chemistry.