TY - JOUR
T1 - Asymmetric inter- and intramolecular cyclopropanations of alkenes catalyzed by rhodium D4-porphyrin
T2 - A comparison of rhodium- and ruthenium-centred catalysts
AU - Teng, Pang-Fei
AU - Lai, Tat-Shing
AU - Kwong, Hoi-Lun
AU - Che, Chi-Ming
PY - 2003/4/4
Y1 - 2003/4/4
N2 - Iodo-(5,10,15,20-tetrakis(1,2,3,4,5,6,7,8-octahydro-1,4:5,8- dimethanoanthracen-9-yl)porphyrinatorhodium(III), designated as [Rh(P*)(I)], was prepared and its catalytic activity in the asymmetric cyclopropanation of alkenes with ethyl diazoacetate (EDA) was examined. High catalyst turnovers (TON >103) and moderate enantioselectivities (up to 68% ee) were observed. However, the obtained trans/cis ratios are low. Competition experiments revealed that electron-donating substituents on styrene accelerate the cyclopropanations. The log(kX/kH) versus σ+ plot for substituted styrenes exhibits a good linearity with a small negative ρ+ value (-0.14). [Rh(P*)(I)] is also active in the intramolecular cyclopropanation of allyl diazoacetates. A comparison between rhodium and ruthenium porphyrin complexes was made. © 2003 Elsevier Science Ltd. All rights reserved.
AB - Iodo-(5,10,15,20-tetrakis(1,2,3,4,5,6,7,8-octahydro-1,4:5,8- dimethanoanthracen-9-yl)porphyrinatorhodium(III), designated as [Rh(P*)(I)], was prepared and its catalytic activity in the asymmetric cyclopropanation of alkenes with ethyl diazoacetate (EDA) was examined. High catalyst turnovers (TON >103) and moderate enantioselectivities (up to 68% ee) were observed. However, the obtained trans/cis ratios are low. Competition experiments revealed that electron-donating substituents on styrene accelerate the cyclopropanations. The log(kX/kH) versus σ+ plot for substituted styrenes exhibits a good linearity with a small negative ρ+ value (-0.14). [Rh(P*)(I)] is also active in the intramolecular cyclopropanation of allyl diazoacetates. A comparison between rhodium and ruthenium porphyrin complexes was made. © 2003 Elsevier Science Ltd. All rights reserved.
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U2 - 10.1016/S0957-4166(03)00047-8
DO - 10.1016/S0957-4166(03)00047-8
M3 - RGC 21 - Publication in refereed journal
SN - 0957-4166
VL - 14
SP - 837
EP - 844
JO - Tetrahedron Asymmetry
JF - Tetrahedron Asymmetry
IS - 7
ER -