2243-35-8Relevant articles and documents
Diaz et al.
, p. 6319,6320-6322 (1977)
Mechanistic Insights into the Formation of δ-Lactones by Cerium-Catalyzed Aerobic Coupling of β-Oxoesters with Enol Acetates
Christoffers, Jens,Speldrich, Jean-Marico
, p. 907 - 914 (2021)
δ-Valerolactone derivatives are formed by the cerium-catalyzed, aerobic coupling of β-oxoesters with enol acetates and dioxygen. The products possess a 1,4-diketone moiety, thus, the conversion can be regarded as an Umpolung since the β-oxoesters are oxidized to electrophilic α-radicals. The transformation has similarities to the Baeyer-Villiger oxidation (BVO) where the higher substituted residue migrates. An endoperoxidic oxycarbenium ion comparable to the Criegee intermediate in the BVO is proposed as a reaction intermediate in this case of the oxidative C?C coupling reaction, but in contrast to the BVO, the less substituted alkyl residue migrates. It was demonstrated by the conversion of β-oxoesters with two stereocenters that this 1,2-alkyl shift proceeds with retention of configuration. A radical chain mechanism of the coupling reaction was furthermore evidenced by the conversion of enol acetates and β-oxoesters with cyclopropyl substituents. Isolation and characterization of products with opened cyclopropane rings established the constitution of radical intermediates.
Clark,Miller
, p. 599 (1977)
Iron-catalyzed ketonization of 2-aryl-1,1-dibromoalkenes with KOAc: Synthesis of α-acetoxy aryl ketones via a Michael-like addition process
Zhao, Ming,Kuang, Chun Xiang,Cheng, Xue Zhi,Yang, Qing
, p. 571 - 574 (2011)
A novel and convenient iron-catalyzed ketonization of 2-aryl-1,1- dibromoalkenes with KOAc has been achieved. A series of α-acetoxy aryl ketones were prepared with moderate yields via 2-carbon position functionalization of 2-aryl-1,1-dibromoalkenes.
Study on the reactive transient α-λ3-iodanyl- acetophenone complex in the iodine(III)/PhI(I) catalytic cycle of iodobenzene-catalyzed α-acetoxylation reaction of acetophenone by electrospray ionization tandem mass spectrometry
Wang, Hao-Yang,Zhou, Juan,Guo, Yin-Long
, p. 616 - 620 (2012)
RATIONALE Hypervalent iodine compounds are important and widely used oxidants in organic chemistry. In 2005, Ochiai reported the PhI-catalyzed α-acetoxylation reaction of acetophenone by the oxidation of PhI with m-chloroperbenzoic acid (m-CPBA) in acetic acid. However, until now, the most critical reactive α-λ3-iodine alkyl acetophenone intermediate (3) had not been isolated or directly detected. METHODS Electrospray ionization tandem mass spectrometry (ESI-MS/MS) was used to intercept and characterize the transient reactive α-λ3- iodine alkyl acetophenone intermediate in the reaction solution. RESULTS The trivalent iodine species was detected when PhI and m-CPBA in acetic acid were mixed, which indicated the facile oxidation of a catalytic amount of PhI(I) to the iodine(III) species by m-CPBA. Most importantly, 3·H+ was observed at m/z 383 from the reaction solution and this ion gave the protonated α-acetoxylation product 4·H+ at m/z 179 in MS/MS by an intramolecular reductive elimination of PhI. CONCLUSIONS These ESI-MS/MS studies showed the existence of the reactive α-λ3-iodine alkyl acetophenone intermediate 3 in the catalytic cycle. Moreover, the gas-phase reactivity of 3·H+ was consistent with the proposed solution-phase reactivity of the α-λ3-iodine alkyl acetophenone intermediate 3, thus confirming the reaction mechanism proposed by Ochiai. Copyright
A Unified Approach for Divergent Synthesis of Heterocycles via TMSOTf-Catalyzed Formal [3+2] Cycloaddition of Electron-Rich Alkynes
Chen, Ping,Cao, Wei,Li, Xiangqian,Shi, Dayong
supporting information, p. 4789 - 4794 (2021/09/02)
We present a synthetic protocol for the construction of polysubstituted five-membered heterocycles via TMSOTf-catalyzed formal [3+2] cycloaddition of electron-rich alkynes, which features free from any metal, atom economy and water as the main by-product. Furthermore, alkenyl ether adduct has been verified as the key intermediate. Notably, by utilizing this approach, we can synthesize a broad range of polysubstituted furans, thiophenes and pyrroles, and extend this transformation to deliver fused-polyheterocycles. This reaction can be achieved on a gram scale and the corresponding products are intermediates for producing diverse potentially useful scaffolds. (Figure presented.).
Sulfur-mediated difunctionalization of internal and terminal alkynes for the synthesis of α-acetoxy ketones
Li, Pingfan,Zhang, Zhong
, (2020/02/13)
The sulfur-mediated difunctionalization of alkynes is reported to give α-acetoxy ketones in a one-pot operation under mild conditions with 19–92% yield. By using wet potassium acetate as both the aqueous base and nucleophilic reagent, both terminal alkynes and internal alkynes could be converted into the α-acetoxy ketone products.
