Refernces
10.1002/cjoc.201800088
The research aims to develop a highly efficient and stereoselective method for constructing chiral four-membered ring compounds, specifically β-lactams and cyclobutanones, which are important in pharmaceuticals and natural products. The study employs an iridium (Ir) catalyst complexed with an axially-unfixed biphenyl phosphine-oxazoline ligand (BiphPHOX) to achieve asymmetric hydrogenation under mild conditions (1.0 - 2.5 bar H? for 1.0 - 10 hours). The reaction conditions were optimized to achieve excellent yields (up to 99%) and enantioselectivities (up to 98%). The study concludes that this method is highly efficient, with a wide substrate scope and potential for further transformations, making it a valuable protocol for the synthesis of chiral four-membered ring compounds.
10.1002/cjoc.201090292
The study investigates the charge-transfer effect on chiral phosphoric acid-catalyzed asymmetric Baeyer-Villiger oxidation of 3-substituted cyclobutanones using 30% aqueous H2O2 as the oxidant. The primary chemicals used include BINOL-derived chiral phosphoric acids as catalysts, 3-aryl cyclobutanones as substrates, and various electron acceptor additives (A1-A7) to modulate enantioselectivity. The purpose of these chemicals is to explore how the intermolecular charge-transfer interaction between the catalyst and electron-deficient additives can fine-tune the enantioselectivity of the asymmetric catalysis, leading to an enhancement of the enantiomeric excess (ee) values in the reaction products.
10.1016/S0040-4039(00)96628-0
The research focuses on the synthesis of 1-methoxy-1-(phenylthio)cyclopropanes from olefins via the Pummerer rearrangement. The purpose of this study was to develop a versatile and mild method for the preparation of cyclobutanones, which are valuable precursors in the synthesis of higher ring systems, acyclic fragments, and natural products. The researchers successfully modified the Pummerer reaction to achieve high yields of the title compounds through a series of steps involving carbene addition, oxidation, and methylation. Key chemicals used in the process include olefins, phenylthiocarbene, m-chloroperbenzoic acid, trimethyloxonium fluoroborate, and sodium methoxide in methanol. The study concluded that the Pummerer rearrangement of methoxysulfonium salts involving cyclopropanes is a highly stereoselective method for preparing fused bicyclic cyclopropanes, which are useful precursors of fused cyclobutanones.
10.1021/acs.orglett.0c00963
This research presents a novel directing-group-based strategy that enables the intermolecular Heck-type reaction of cycloketone oxime esters with unactivated alkenes, marking the first achievement in coupling nonstabilized alkyl radicals with unactivated olefins. The study's purpose was to develop a method for constructing Csp2?Csp3 bonds, which are significant in organic synthesis. Key chemicals used in the process include copper salts as catalysts, DMSO as an initial solvent, and 2-butanol, which was found to be the most effective solvent for controlling both regio- and diastereoselectivities. The reaction's compatibility with various unactivated alkenes and oxime esters derived from cyclobutanone, cyclopentanone, and cyclohexanone was demonstrated, showcasing the potential application of this methodology in organic synthesis.
F+
