With the aid of a class of newly discovered Trost-type bisphosphine ligands bearing a chiral cycloalkane framework, the Pd-catalyzed decarboxylative dearomative asymmetric allylic alkylation (AAA) of benzofurans was achieved with high efficiency [0.2-1.0 mol% Pd2(dba)3/L], good generality and high enantioselectivity (> 30 examples, 82-99% yield and 90-96% ee). Moreover, a diversity-oriented synthesis
Cyclometalated Chiral-at-Ruthenium Catalyst for Enantioselective Ring-Closing C(sp<sup>3</sup>)–H Carbene Insertion to Access Chiral Flavanones
作者:Feng Han、Peter H. Choi、Chen-Xi Ye、Yvonne Grell、Xiulan Xie、Sergei I. Ivlev、Shuming Chen、Eric Meggers
DOI:10.1021/acscatal.2c02423
日期:2022.8.19
A competing oxygen attack pathway involving the formation and [1,2]-shift (Stevensrearrangement) of an oxonium ylide intermediate was successfully suppressed in favor of a catalytic enantioselective ring-closing C(sp3)–H carbene insertion. Density functional theory calculations provide a rationale for the observed C–H insertion over the undesirable C–O formation pathway. The method provides access
A Strategic Synthesis of Fluoroethers via Ring-Opening Fluorinative Beckmann Fragmentation
作者:Chae Yeon Lee、Su Eun Lee、Hee Nam Lim
DOI:10.1021/acs.orglett.3c02343
日期:2023.9.8
An SN1-type fluorination method for monofluoroethers is developed. The key to this reaction is fluorinative C–C bond cleavage that is driven by oxygen-assisted Beckmann fragmentation. To enable this transformation, cyclic α-aryloxyoximes derived from 3-coumaranone and 1-indanones were investigated as substrates, using N,N-diethylaminosulfur trifluoride (DAST) as a dual-role reagent of an oxime activator
Synthesis of β-Keto-phosphotriesters Using Functionalized Diazoketones
作者:T. Gefflaut、Jacques Périé
DOI:10.1080/00397919408012621
日期:1994.1
Convenient substitution (Ac) on the heteroatom in diazo ketones as in compounds 6, 8 or 10, prevents the classical cyclisation reaction and allows intermolecular addition; the reaction is applied to phosphorylation (reaction 1).
Ruthenium-Catalyzed Synthesis of <i>cis</i>-2,3-Dihydrobenzofuran-3-ols by Aqueous Transfer Hydrogenation via Dynamic Kinetic Resolution
The preparation of cis-2,3-dihydrobenzofuranols with two stereocenters through aqueous asymmetric transfer hydrogenation (ATH) of benzofuranones with the metal catalyst Ru(II) via dynamic kinetic resolution (DKR) has been developed. A variety of alpha-alkyl benzofuranones were transformed to obtain optically pure 2,3-dihydrobenzofuran-3-ols with excellent enantioselectivities and acceptable yields under mild conditions.