Phosphine-Mediated [3+2] Cycloaddition Reactions of Ethyl 5,5-Diarylpenta-2,3,4-trienoates with Arylmethylidenemalononitriles and <i>N</i>-Tosylimines

Ethyl 5,5-diarylpenta-2,3,4-trienoates were synthesized and utilized in the phosphine-mediated [3+2] cycloaddition reactions with arylmethylidenemalononitriles and N-tosylimines in the presence of tributylphosphine. These reactions provide an easy access to a variety of novel polysubstituted cyclopentenes or pyrrolidines in good to excellent yields under mild conditions.