3587-66-4Relevant academic research and scientific papers
Tandem Acid/Pd-Catalyzed Reductive Rearrangement of Glycol Derivatives
Ciszek, Benjamin,Fleischer, Ivana,Kathe, Prasad,Schmidt, Tanno A.
supporting information, p. 3641 - 3646 (2020/03/25)
Herein, we describe the acid/Pd-tandem-catalyzed transformation of glycol derivatives into terminal formic esters. Mechanistic investigations show that the substrate undergoes rearrangement to an aldehyde under [1,2] hydrogen migration and cleavage of an oxygen-based leaving group. The leaving group is trapped as its formic ester, and the aldehyde is reduced and subsequently esterified to a formate. Whereas the rearrangement to the aldehyde is catalyzed by sulfonic acids, the reduction step requires a unique catalyst system comprising a PdII or Pd0 precursor in loadings as low as 0.75 mol % and α,α′-bis(di-tert-butylphosphino)-o-xylene as ligand. The reduction step makes use of formic acid as an easy-to-handle transfer reductant. The substrate scope of the transformation encompasses both aromatic and aliphatic substrates and a variety of leaving groups.
Alkoxyl Radicals Generated under Photoredox Catalysis: A Strategy for anti-Markovnikov Alkoxylation Reactions
Barthelemy, Anne-Laure,Tuccio, Béatrice,Magnier, Emmanuel,Dagousset, Guillaume
supporting information, p. 13790 - 13794 (2018/09/10)
Reported herein is a novel photoredox-catalyzed approach for ether synthesis and it involves alkoxyl radicals generated from N-alkoxypyridinium salts. A wide range of alkenes are smoothly difunctionalized in an anti-Markovnikov fashion, affording various functionalized alkyl alkyl ethers. Notably, this mild process tolerates a number of functional groups and is efficiently carried out under both batch and flow conditions. Importantly, electron paramagnetic resonance (EPR) experiments by spin trapping were carried out to characterize the radical intermediates involved in this radical/cationic process.
Mechanistic Insight into Additions of Allylic Grignard Reagents to Carbonyl Compounds
Bartolo, Nicole D.,Woerpel
, p. 10197 - 10206 (2018/09/06)
Allylic Grignard reagents exhibit high reactivity and low selectivity in additions to carbonyl compounds. Additions of allylic Grignard reagents to carbonyl compounds were investigated using prenylmagnesium chloride as a mechanistic probe. When the carbonyl group is relatively unhindered, the addition proceeds through a six-membered transition state with allylic transposition. This process generally occurs with no diastereoselectivity because the reaction rates approach the diffusion limit. With hindered ketones, however, this pathway is disfavored, and the addition proceeds through a transition state resembling that of other Grignard reagents.
Visible light-promoted dihydroxylation of styrenes with water and dioxygen
Yang, Bo,Lu, Zhan
, p. 12634 - 12637 (2017/12/02)
An efficient visible light promoted metal-free dihydroxylation of styrenes with water and dioxygen has been developed for the construction of vicinal alcohols. The protocol was operationally simple with a broad substrate scope. The mechanistic studies demonstrated that one of the hydroxyl groups came from water and the other one came from molecular oxygen. Additionally, the β-alkyoxy alcohols could also be obtained using a similar strategy.
Additions of Organomagnesium Halides to α-Alkoxy Ketones: Revision of the Chelation-Control Model
Read, Jacquelyne A.,Yang, Yingying,Woerpel
supporting information, p. 3346 - 3349 (2017/07/13)
The chelation-control model explains the high diastereoselectivity obtained in additions of organometallic nucleophiles to α-alkoxy ketones but fails for reactions of allylmagnesium halides. Low diastereoselectivity in ethereal solvents results from no chelation-induced rate acceleration. Additions of allylmagnesium bromide to carbonyl compounds are diastereoselective using CH2Cl2 as the solvent even though rate acceleration is still absent. Stereoselectivity likely arises from the predominance of the chelated form in solution. Therefore, a revised chelation-control model is proposed.
Thermolysis of substituted tert-butyl-(2-phenyl-prop-2-yl) peroxides
Suprun
, p. 363 - 368 (2007/10/03)
tert-Butyl-(2-phenyl-1-methoxy-prop-2-yl)-peroxide (1a), tert-butyl-(2-phenyl-1-acetoxy-prop-2-yl)-peroxide (1b) and tert-butyl-(1,2-diphenyl-prop-2-yl)-peroxide (1c) were prepared from t-BuOOH and 1-methoxy-2-phenyl-prop-2-ol (a), 2-phenyl-2-methyl-oxirane (b) and, respectively, 1,2-diphenyl-propan-2-ol (c). The peroxides 1a-c were characterized by NMR spectroscopy and elemental analysis. Kinetic data were determined and the products analyzed from thermolysis of 1a-c at 110-155°C in cumene as the solvent. The major thermolysis product from 1a-c was acetophenone, formed via fragmentation of intermediate alkoxy radicals: R-CH2-C(Ph)(Me)O (R: MeO (a); AcO (b); Ph (c)). Wiley-VCH Verlag GmbH, 1999.
Alcoxymethyltributyletains precurseurs d'alcoxymethyllithiums: application a la synthese de monoethers d'α-glycols et a l'homologation de cetones en aldehydes
Duchene, Alain,Mouko-Mpegna, David,Quintard, Jean-Paul
, p. 787 - 793 (2007/10/02)
Ethoxymethyltributyltin (obtained from diethoxymethyltributyltin, acetyl chloride and tributyltin hydride) and methoxymethyltributyltin (obtained from chloromethyl-methyl ether and tributylstannylmagnesium chloride) have been transmetallated with butyllithium to give the corresponding alkoxymethyl lithium reagents.This reaction, although usually performed in ether, is possible in a variety of other solvents thus simplifying some of the problems encountered during isolation of the products.The alkoxymethyllithiums obtained react with aldehydes and ketones to give cleanly the corresponding monoprotected α-glycols.Stereochemical trends were observed for hydratropaldehyde and 4-tertiarybutylcyclohexanone, while regiochemical trends were evaluated in the case of cyclohexen-2-one.Syntheis of aldehydes has been achieved in good yields from tertiary monoprotected α-glycols using conventional methods.
