27602-75-1Relevant articles and documents
An Asymmetric SN2 Dynamic Kinetic Resolution
Rezayee, Nomaan M.,Enem?rke, Valdemar J.,Linde, Sif T.,Lamhauge, Johannes N.,Reyes-Rodríguez, Gabriel J.,J?rgensen, Karl Anker,Lu, Chenxi,Houk
supporting information, p. 7509 - 7520 (2021/05/26)
The SN2 reaction exhibits the classic Walden inversion, indicative of the stereospecific backside attack of the nucleophile on the stereogenic center. Observation of the inversion of the stereocenter provides evidence for an SN2-type displacement. However, this maxim is contingent on substitution proceeding on a discrete stereocenter. Here we report an SN2 reaction that leads to enantioenrichment of product despite starting from a racemic mixture of starting material. The enantioconvergent reaction proceeds through a dynamic Walden cycle, involving an equilibrating mixture of enantiomers, initiated by a chiral aminocatalyst and terminated by a stereoselective SN2 reaction at a tertiary carbon to provide a quaternary carbon stereocenter. A combination of computational, kinetic, and empirical studies elucidates the multifaceted role of the chiral organocatalyst to provide a model example of the Curtin-Hammett principle. These examples challenge the notion of enantioenriched products exclusively arising from predefined stereocenters when operating through an SN2 mechanism. Based on these principles, examples are included to highlight the generality of the mechanism. We anticipate the asymmetric SN2 dynamic kinetic resolution to be used for a variety of future reactions.
New process for synthesizing racemic naproxen based on Heck coupling
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, (2021/08/06)
The invention discloses a novel process for synthesizing racemic naproxen based on Heck coupling, which comprises the following steps: (1) carrying out Heck coupling reaction on 2-X substituted-6-methoxynaphthalene and crotonamide in an aprotic organic solvent under the action of a palladium catalyst and alkali to generate 3-(6-methoxynaphthyl-2-)-crotonamide; and (2) carrying out Hofmann degradation reaction on the 3-(6-methoxynaphthyl-2-)-crotonamide in an alkaline solution of hypochlorite to generate 2-(6-methoxynaphthyl-2-)-propionaldehyde, directly adding the 2-(6-methoxynaphthyl-2-)-propionaldehyde into chlorite without separation, and conducting oxidizing at room temperature to obtain racemic naproxen. The process provided by the invention does not need to prepare a highly active Grignard reagent, does not need a harsh anhydrous condition, and is relatively high in conversion rate and easy in product purification.
Copper-catalyzed hydroformylation and hydroxymethylation of styrenes
Franke, Robert,Geng, Hui-Qing,Meyer, Tim,Wu, Xiao-Feng
, p. 14937 - 14943 (2021/12/02)
Hydroformylation catalyzed by transition metals is one of the most important homogeneously catalyzed reactions in industrial organic chemistry. Millions of tons of aldehydes and related chemicals are produced by this transformation annually. However, most of the applied procedures use rhodium catalysts. In the procedure described here, a copper-catalyzed hydroformylation of alkenes has been realized. Remarkably, by using a different copper precursor, the aldehydes obtained can be further hydrogenated to give the corresponding alcohols under the same conditions, formally named as hydroxymethylation of alkenes. Under pressure of syngas, various aldehydes and alcohols can be produced from alkenes with copper as the only catalyst, in excellent regioselectivity. Additionally, an all-carbon quaternary center containing ethers and formates can be synthesized as well with the addition of unactivated alkyl halides. A possible reaction pathway is proposed based on our results. This journal is
