[reaction: see text] The ruthenium porphyrin-catalyzed reactions of diazo ketones with pi-unsaturated compounds via carbonyl ylide formation/cycloaddition cascade exhibit product yields and selectivities comparable to the analogous reactions with dirhodium carboxylates as catalysts. By grafting a ruthenium porphyrin on poly(ethylene glycol) (Zhang, J.-L.; Che, C.-M. Org. Lett. 2002, 4, 1911), a recyclable catalytic system is developed with over 5700 product turnovers attained for the reaction of 1-diazo-2,5-hexanedione with dimethyl acetylenedicarboxylate.