Cyclopropanation of alkenes with ethyl diazoacetate catalysed by ruthenium porphyrin complexes

Asymmetric heterogeneous carbene transfer catalyzed by optically active ruthenium spirobifluorenylporphyrin polymers

“…Optically active ruthenium porphyrin complexes have been the focus of intense studies by us 19,29,39 and others 26,40-42 as catalysts for asymmetric cyclopropanation. In contrast, immobilizing chiral metalloporphyrins under insoluble materials is still rare.…”

“…To assign the signals to the corresponding cyclopropane, we carried out the previously described homogeneous reaction, 29 allowing us to determine the enantiomeric excess in both trans and cis cyclopropanes, and also the absolute configuration of the products. With these reactive substrates, cyclopropanation yields .…”

Metalloporphyrin Symmetry in Chiral Recognition and Enantioselective Catalysis

“…Recent growth in the area of transition metal porphyrin chemistry has, in part, been driven by the increased interest associated with metal-catalyzed cyclopropanation. Despite the periodic relationship of ruthenium to iron and osmium and the syntheses of different carbene complexes of ruthenium porphyrins, elegantly developed by Collman et al [32], it is only in 1997 that cyclopropanation reactions were observed using ruthenium porphyrins as catalysts (Figure 4) [33].…”

“…The reaction of styrene with ethyl diazoacetate in the presence of the dioxoruthenium(VI) picket-fence complex bearing optically active α-methoxy-α(trifluoromethyl) phenylacetyl residues on both sides of the porphyrin plane (α,β,α,β isomer, D 2 symmetry) gave a mixture (trans/cis: 9/1) of optically active cyclopropane derivatives, i.e., trans-and cis-2-phenylcyclopropanecarboxylic esters with 14% and 34% ee, respectively [33]. Better enantioselectivity was obtained with a chiral ruthenium porphyrin showing higher symmetry.…”

Synthesis and chemical reactivity of new zinc porphyrin diazoacetates catalyzed by ruthenium and iron porphyrins

“…The formation of the trans isomer, which was confirmed by NOESY spectroscopy, is similar to that observed when ethyl diazoacetate is used as reactant. 22 The insertion of electrophilic carbenes in the N-H bonds of protected -amino esters or amides is a powerful method for N-alkylating this class of compounds. 23 Since we 7,8 and others [24][25][26][27] previously reported N-H insertion of diazoesters catalyzed by metalloporphyrins (Fe, Ru), N-H insertion with a diazo porphyrin ester was also investigated (Scheme 2).…”