Inspired by the chemistry and biology of butyrolactones, pyrrolidines, and chromanones,
we successfully developed a simple domino 1,3-dipolar cycloaddition of homoserine-lactone-derived
azomethine ylides for the construction of biologically important spiro[butyrolactone–pyrrolidine–chromanone]
hybrids in the presence of Et3N as a catalyst under mild conditions. The reaction 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 (up to 85% yield and >20:1
diastereomeric ratio) via an exo-transition state. This is the first example of an introduction of a chromanone moiety
into a spiro[butyrolactone-pyrrolidine] framework, which might be valuable in medicinal
chemistry.
Key words
1,3-dipolar cycloaddition - chromones - spiro compounds - azomethine ylides - pyrrolidines
- lactones