1775-27-5Relevant articles and documents
Synthesis and spectral properties of fluorescent photochromic diarylethenes with 6,6a-dihydropentalene-2(1H)-one ethene "bridge"
Lonshakov, Dmitry V.,Shirinian, Valerii Z.,Zavarzin, Igor V.,Lvov, Andrey G.,Krayushkin, Mikhail M.
, p. 105 - 112 (2014)
An alternative synthetic strategy for the preparation of 6,6a-dihydropentalene-2(1H)-one derivatives comprising the stage of the regioselective α-bromination of cyclopentenone system has been proposed. The method along with the bromination process includes the alkylation of ethyl 4-aryl-3-oxobutanoate with bromocyclopentenones and intramolecular carbocyclization reaction of alkylated product. The cyclization reaction has been studied in detail and it was found that the yields of the main and side products depend strongly on alkali concentration, and the method can be also used to design 8,8a-dihydrocyclopenta[a]inden-2(1H)-one unit. The spectral properties of the compounds obtained have been studied, and it was found that pentalenone derivatives as well as starting cyclopentenones, exhibit photochromic properties; in addition, the former, unlike the latter, are also fluorescent.
Nickel - promoted favorskii type rearrangement of cyclic α-bromoketones
Tandon, Vishnu K.,Awasthi, Anoop K.,Singh, Kunwar A.,Maurya, Hardesh K.,Gautam, Sanjay K.
, p. 593 - 600 (2010)
Favorskii type rearrangement of cyclic α-bromo ketones 2 is promoted by NiCl2 in refluxing methanol, giving the rearranged carboxylic acid ester 3 in excellent yields. The reaction of 4-bromo-2,3,4,5-tetrahydronaphth [2,1-b]oxepin-5-one (5) and its regioisomer 8 with NiCl2 in McOH resulted in Favorskii rearranged carboxylic acid esters 6 and 9 respectively.
Acridine Orange Hemi(Zinc Chloride) Salt as a Lewis Acid-Photoredox Hybrid Catalyst for the Generation of α-Carbonyl Radicals
Das, Sanju,Mandal, Tanumoy,De Sarkar, Suman
supporting information, p. 755 - 765 (2021/12/10)
A readily accessible organic-inorganic hybrid catalyst is reported for the reductive fragmentation of α-halocarbonyl compounds. The robust hybrid catalyst is a self-stabilizing combination of ZnCl2 Lewis acid and acridine orange as the photoactive organic dye. Mechanistic specifics of this hybrid catalyst have been studied in detail using both photophysical and electrochemical experiments. A systematic study enabled the discovery of the appropriate Lewis acid for the effective LUMO stabilization of α-halocarbonyl compounds and thereby lowering of reduction potential within the range of a standard organic dye. This strategy resolves the issues like dehalogenative hydrogenation or homo-coupling of alkyl radicals by guiding the photoredox cycle through an oxidative quenching pathway. The cooperativity between the photoactive organic dye and the Lewis acid counterparts empowers functionalization with a wide range of coupling partners through efficient and controlled generation of alkyl radicals and serves as an appropriate alternative to the expensive late transition metal-based photocatalysts. To demonstrate the application potential of this cooperative catalytic system, four different synthetic transformations of α-carbonyl bromides were explored with broad substrate scopes.
The absolute configuration of 2-bromo-2,3-dihydro-1H-inden-1-ols
Prysiazhnuk, Dmitry V.,Rusanov, Eduard B.,Kolodiazhnyi, Oleg I.
, p. 3023 - 3031 (2021/08/13)
All four possible stereoisomers of cis- and trans-2-bromo-2,3-dihydro-1H-inden-1-ols, which are important intermediates in the synthesis of biologically active compounds, were synthesized and their configurations were studied by enzymatic kinetic resoluti
A metal-free aerobic oxidative bromination of anilines and aryl ketones with 2-methylpyridinium nitrate as a reusable ionic liquid
Li, Ming-Fang,Wang, Jian,Ke, Yong-Xin,Pan, Song-Cheng,Yin, Hong,Du, Wenting,Li, Jing-Hua
, p. 267 - 270 (2020/01/08)
An aerobic oxidative bromination of anilines and aryl ketones catalyzed by recyclable 2-methylpyridinium nitrate ionic liquid is achieved in water using hydrobromic acid as the bromine source and molecular oxygen as the oxidant. The catalytic system shows good efficiency and atom economy.
Annulation reaction of cyclic pyridinium ylides with: In situ generated azoalkenes for the construction of spirocyclic skeletons
Quan, Bao-Xue,Yuan, Wei-Cheng,Zhang, Ming-Liang,Zhang, Xiao-Mei,Zhao, Jian-Qiang,Zhou, Ming-Qiang,Zhuo, Jun-Rui
supporting information, p. 1886 - 1891 (2020/03/23)
Two new types of cyclic pyridinium ylides were designed and further used in reactions with azoalkenes to access structurally diverse spirocyclic compounds. A range of spiropyrazoline oxindoles could be smoothly obtained in up to 99% yield via a [4 + 1] annulation process with oxindole 3-pyridinium ylides as C1 synthons. Similarly, a series of spiropyrazoline indanones could be prepared with indanone 2-pyridinium ylides as C1 synthons. This work represents the first example of cyclic pyridinium ylides as C1 synthons for the efficient construction of spirocyclic compounds.
Method of utilizing micro channel reactor to prepare pentafluorophenoxyl ketones continuously
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Paragraph 0056-0057, (2019/06/30)
The invention discloses a method of utilizing a micro channel reactor to prepare pentafluorophenoxyl ketones continuously. Cheap and easily available styrene and pentafluorophenol are taken as the primary raw materials, two step continuous reactions are carried out in a micro channel reactor to obtain pentafluorophenoxyl ketones, the reaction time is shortened to several minutes from several hours; the product yield is high, the reaction efficiency is obviously enhanced, no any pricy organic catalyst or metal catalyst is needed, the operation is simple, the cost is low, the preparation technology is easy to control, the safety is high, the reaction conditions are mild, and the method can be applied to industrial production.
A Method for the Catalytic Enantioselective Synthesis of Chiral α-Azido and α-Amino Ketones from Racemic α-Bromo Ketones, and Its Generalization to the Formation of Bonds to C, O, and S
Da Silva Gomes, Roberto,Corey
supporting information, p. 20058 - 20061 (2019/12/27)
A new and practical method has been developed for the transformation of racemic α-bromo ketones to chiral α-azido and α-amino ketones with high enantioselectivity using phase transfer, ion-pair mediated reactions with a recoverable chiral quaternary salt (10 mol %) as catalyst in fluorobenzene-water. The process has been generalized to a variety of other attachments including of C, O, S, and NHR.
The Electrophilic Fluorination of Enol Esters Using SelectFluor: A Polar Two-Electron Process
Wood, Susanna H.,Etridge, Stephen,Kennedy, Alan R.,Percy, Jonathan M.,Nelson, David J.
supporting information, p. 5574 - 5585 (2019/03/21)
The reaction of enol esters with SelectFluor is facile and leads to the corresponding α-fluoroketones under mild conditions and, as a result, this route is commonly employed for the synthesis of medicinally important compounds such as fluorinated steroids. However, despite the use of this methodology in synthesis, the mechanism of this reaction and the influence of structure on reactivity are unclear. A rigorous mechanistic study of the fluorination of these substrates is presented, informed primarily by detailed and robust kinetic experiments. The results of this study implicate a polar two-electron process via an oxygen-stabilised carbenium species, rather than a single-electron process involving radical intermediates. The structure–reactivity relationships revealed here will assist synthetic chemists in deploying this type of methodology in the syntheses of α-fluoroketones.
Synthesis of α,β-dibromo ketones by photolysis of α-bromo ketones with N-bromosuccinimide: Photoinduced β-bromination of α-bromo ketones
Moon, Da Yoon,An, Sejin,Park, Bong Ser
, (2019/10/28)
Irradiation of α-bromopropiophenones in the presence of NBS results in the formation of α,β-dibromopropiophenones, which can be viewed as β-bromination of α-bromopropiophenones. The reaction is believed to go through a series of reactions; photoinduced C–Br bond cleavage, elimination of HBr to give α,β-unsaturated ketone intermediates, and addition of Br2, which are formed by the reaction between HBr and NBS. From mechanistic studies of the reaction, we have also found a very convenient method for α-debromination of the α,β-dibromopropiophenones which is by simple irradiation of the dibromo ketones in acetone or 2-propanol without the use of any additives. Our results demonstrate that bromine can be added into or eliminated from the alpha, beta, or both positions to the carbonyl group by photochemical methods, which make synthetic options of bromine containing carbonyl compounds versatile.
