Refernces
10.1039/c39810000482
The research investigates the oxidation capabilities of the mono-oxygenase system from Methylococcus capsulatus on various substrates including cyclopropane, methylcyclopropane, and certain aromatic compounds. The study found that cyclopropane is oxidized to cyclopropanol, while methylcyclopropane yields cyclopropylmethanol. For aromatic substrates, the enzyme shows regioselectivity, oxidizing monosubstituted benzenes to para-substituted phenols and exhibiting an NIH shift in the oxidation of ethylbenzene. The oxidation products were identified using techniques such as gas-liquid chromatography (g.l.c.), thin-layer chromatography (t.l.c.), and nuclear magnetic resonance (n.m.r.) spectroscopy. The results suggest that the enzyme's mechanism involves the conversion of dioxygen into a metal-bound oxygen species capable of inserting into C-H bonds and adding to C=C bonds. The study also noted spatial restrictions at the enzyme's active site, as larger substituents like t-butyl and 1-methylcyclopropyl-benzene were not oxidized.
10.1002/anie.201908994
The research focuses on the synthesis of doubly activated cyclopropanes through a metal-free process using blue LED irradiation of iodonium ylides with alkenes. The experiments involve mixing alkenes with β-dicarbonyl-derived iodonium ylides and exposing them to blue LED light, resulting in cyclopropanes with yields up to 96%. The study includes both cyclic and acyclic ylides, as well as a variety of electronically diverse alkenes. Computational analysis was employed to explain the high selectivity of the process, suggesting that it proceeds through exclusive HOMO to LUMO excitation, rather than free carbene generation. The procedure is operationally simple, does not require a photocatalyst, and provides access to important building blocks for complex molecule synthesis in a single step. The analyses used in the study include UV/Vis spectroscopy, time-dependent (TD) DFT calculations, and natural population analysis to predict and confirm the electronic excitation and reaction mechanisms.
10.1016/S0957-4166(00)00327-X
The study focuses on the stereocontrolled cyclopropanation of enones derived from (S)-Garner’s aldehyde, aiming to synthesize 1,2,3-trisubstituted cyclopropanes with potential biological activities. The researchers utilized sulfonium ylides, specifically ethyl (dimethylsulfuranylidene)acetate (EDSA), generated in situ from ethyl dimethylsulfonium acetate bromide and DBU (1,8-diazabicyclo[5.4.0]undec-7-ene), to react with enones 5 derived from (S)-Garner’s aldehyde in toluene. The major isomer produced from this reaction was found to have the configuration 2R,1’S,2’S,3’S. The study also explored the synthesis of a 3-benzyl analogue of the CCG family compounds, which are known for their biological significance. Various enones, sulfonium ylides, and reaction conditions were investigated to assess the scope and diversity of the reaction, ultimately concluding that the reaction allows for the assembly of 1,2,3-trisubstituted cyclopropanes with great diversity, potentially leading to the synthesis of biologically important compounds such as CCG analogues.
10.1055/s-2004-835663
The study presents a novel methodology for synthesizing N-diphenylmethylene-2-vinyl-substituted cyclopropylamines, which are significant in pharmaceuticals and natural products due to their biological activity. The synthesis begins with allylsulfones, specifically compound 11, which can be obtained in both enantiomeric forms. The researchers utilized various chemicals, including base treatments for allylsulfones to form trans:cis cyclopropanols, and molecular modeling to study the stereoselectivity of cyclopropane formation. The study also involved the use of Garner’s aldehyde, a key intermediate in synthesizing biologically active compounds, and the transformation of amino alcohols into cyclopropylamines with the help of protecting groups like Tosyl, Boc, Moc, and benzyl. The purpose of these chemicals was to achieve high diastereoselectivity in the synthesis of chiral amino-cyclopropanes, which are valuable as building blocks for the synthesis of conformationally restricted amino acids. The study's innovative approach and findings contribute to the field of asymmetric synthesis, particularly for cyclopropylamines.
F+
