Cyclopentadienylidenetriphenylphosphorane (the Ramirez ylide), unexpectedly and contrary to a no. of earlier reports, has been shown to be like pyrrole in undergoing electrophilic substitution on the cyclopentadienide ring at either the 3- or the 2-position, depending on the electrophile.  Formylation under Vilsmeier conditions and addn. of tetracyanoethylene occurs at the 3-position, while activated acetylenes and the nitrosyl electrophile substitute at the 2 position.  The 3-formylated product was reduced to the 3-Me deriv. and it also reacted under Knoevenagel conditions to give a no. of novel condensation products.  The results of single-crystal X-ray crystallog. analyses are given for four of the compds. studied, and a careful 2D NMR anal. of all of the compds. was performed in order to develop a reliable method for the unambiguous assignment of the regiochem. of adduct formation.