α-Diazoacetates as Carbene Precursors: Metallosalen-Catalyzed Asymmetric Cyclopropanation
作者:Tsutomu Katsuki、Tatsuya Uchida
DOI:10.1055/s-2006-926448
日期:2006.5
Readily available α-diazo compounds have been shown to be efficient carbene precursors for asymmetric cyclopropanation using ruthenium(NO)-salen and cobalt-salen complexes, as catalysts. The stereoselectivity of the cyclopropanation depends on the metal ion, its valency, the structural and electronic nature of the salen ligand, and the apical ligand of the salen complex used. Both trans- and cis-selective asymmetric intermolecular cyclopropanation can be realized under mild conditions by using a suitable metallosalen complex. Furthermore, a wide range of alkenyl α-diazoacetates and the related alkenyl diazomethyl ketones undergo intramolecular cyclopropanation in a highly enantioselective manner by using various metallosalen complexes, easily prepared in a modular fashion, as catalyst.
Stereodivergent Intramolecular Cyclopropanation Enabled by Engineered Carbene Transferases
作者:Ajay L. Chandgude、Xinkun Ren、Rudi Fasan
DOI:10.1021/jacs.9b02700
日期:2019.6.12
myoglobin biocatalysts for executing asymmetric intramolecular cyclopropanations resulting in cyclopropane-fused γ-lactones, which are key motifs found in many bioactive molecules. Using this strategy, a broad range of allyl diazoacetate substrates were efficiently cyclized in high yields with up to 99% enantiomeric excess. Upon remodeling of the active site via protein engineering, myoglobin variants
Optically active Co(II)–salencomplexes (5 and 7) were found to catalyze highlyenantioselective intramolecular cyclopropanation of 2-alkenyl α-diazoacetates in the presence of N-methylimidazole under high substrate concentration.
Intramolecular Asymmetric Cyclopropanation with (Nitroso)(salen)ruthenium(II) Complexes as Catalysts
作者:Biswajit Saha、Tatsuya Uchida、Tsutomu Katsuki
DOI:10.1055/s-2001-9733
日期:——
Intramolecular cyclopropanation of (E)-2-alkenyl-α-diazoacetates was carried out with good to high enantioselectivity by using (nitroso)(salen)ruthenium(II) complexes as catalysts under photo-irradiation.