Ruthenum (II) porphyrins and dirhodium (II) acetate catalyze cyclization of γ-alkoxy-α-diazo- β-ketoesters to (Z)-4-(alkyloxycarbonylmethylidene)-1, 3-dioxolanes selectively (ca. 68% yield) with no formation of 3 (2H)-furanones. Reacting a diazo ketoester with [RuII (TTP)(CO)][H2TTP= meso-tetrakis (p-tolyl) porphyrin] in toluene afforded a ruthenium carbenoid complex, which has been isolated and spectroscopically characterized. A ...