The title compound, C25H25F3N2OS2, is one of two isomeric 1:1 cycloadducts of a thermally generated isopropoxy-substituted nitrile ylide and 2-phenyl-3-thia-1-azaspiro[4.4]non-1-ene-4-thione. The structure shows the regiochemistry of the formation of the major isomer. The cyclopentane ring is disordered and shows both a half-chair and an envelope conformation. The heterocyclic rings have envelope conformations. The C-C bonds involving the heterocyclic spiro C atom are elongated due to electronic effects from the neighbouring S atoms. Delocalization effects result in asymmetric S-C bond lengths.