Ruthenium(II) porphyrin catalyzed formation of (Z)-4-alkyloxycarbonyl- methylidene-1,3-dioxolanes from gamma-alkoxy-alpha-diazo-beta-ketoesters.
[reaction: see text] Ruthenum(II) porphyrins and dirhodium(II) acetate catalyze cyclization of gamma-alkoxy-alpha-diazo-beta-ketoesters to (Z)-4-(alkyloxycarbonylmethylidene)-1,3-dioxolanes selectively (ca. 68% yield) with no formation of 3(2H)-furanones. Reacting a diazo ketoester with [Ru(II)(TTP)(CO)] [H(2)TTP = meso-tetrakis(p-tolyl) porphyrin] in toluene afforded a ruthenium carbenoid complex, which has been isolated and spectroscopically characterized. A mechanism involving hydrogen atom migration from the C-H bond to the ruthenium carbenoid is proposed.
Zheng
Shi-Long
SL
Department of Chemistry and Open Laboratory of Chemical Biology of the Institute of Molecular Technology for Drug Discovery and Synthesis, The University of Hong Kong, Pokfulam Road, Hong Kong.
Yu
Wing-Yiu
WY
Che
Chi-Ming
CM