Construction of aryliridium-salen complexes: enantio- and cis-selective cyclopropanation of conjugated and nonconjugated olefins.
Two stable and optically active iridium-salen complexes were synthesized by introducing a tolyl or phenyl ligand at the apical position, respectively, via the S(E)Ar mechanism, and they were found to be efficient catalysts for cis-selective asymmetric cyclopropanation. The scope of the cyclopropanation was wide, and the reactions of not only conjugated mono-, di-, and trisubstituted olefins but also nonconjugated terminal olefins proceeded with high enantio- and cis-selectivity, even in the presence of a functional group such as an ether or ester. The utility of this cyclopropanation was demonstrated by a short step synthesis of 8-[(1R,2S)-2-hexylcyclopropyl]octanoate, isolated from Escherichia coli B-ATCC 11303, using the reaction as the key step.
Suematsu
Hidehiro
H
Department of Chemistry, Faculty of Science, Graduate School, Kyushu University, Hakozaki, Higashi-ku, Fukuoka 812-8581, Japan.
Kanchiku
Shigefumi
S
Uchida
Tatsuya
T
Katsuki
Tsutomu
T