Visible-Light-Mediated Radical Aryldifluoroacetylation of Alkynes with Ethyl Bromodifluoroacetate for the Synthesis of 3-Difluoroacetylated Coumarins

Abstract

A mild and efficient method for the synthesis of 3-difluoroacetylated coumarins through visible-light-promoted aryldifluoroacetylation of alkynes with ethyl bromodifluoroacetate has been developed. The reaction allows the direct formation of Csp(2)-CF2COOEt and C-C bonds via a proposed tandem radical cyclization process.

Visible‐light‐catalyzed Tandem Difluoroacetylation–Intramolecular Cyclization of 1,3‐Diarylpropynones: Access to Difluoroacetylated Indenones

“…The mechanism proposed on the basis of control experiments and related literature reports [7][8][9][10][11][12][13][14][15] is illustrated in Scheme 4. Initially, the photocatalyst [fac-Ir III (ppy) 3 ]e xcited by Scheme1.Schematicrepresentation of the present work versus earlier works.…”

“…[6] Consequently,t he visible-light-photocatalyzedg eneration and addition of ad ifluoromethyl radical to unsaturated systems followed by intramolecular cyclization has emerged as an attractive method for the synthesis of difluoromethylated heterocycles such as pyridine, [7] isoquinolinediones, [8] oxindole, [8,9] lactones, [10] phenanthridine, [11] benzo[j]phenanthridine, [12] quinolone-2-ones, [13] and 1-azaspiro[4.5]decanes. [15] Although the synthesis of an indenone scaffold through radicalcyclization of alkynones has been reported in the literature, [16] to the best of our knowledge,t he difluoroalkylation of alkynones under visible light photoredox conditions has not been exploitedf or the synthesis of difluoroalkylated indenones (Scheme 1). [15] Although the synthesis of an indenone scaffold through radicalcyclization of alkynones has been reported in the literature, [16] to the best of our knowledge,t he difluoroalkylation of alkynones under visible light photoredox conditions has not been exploitedf or the synthesis of difluoroalkylated indenones (Scheme 1).…”

Palladium‐Catalyzed Carboperfluoroalkylation of Alkynes with Fluoroalkyl Iodides and Arylstannanes

“…For instance, fluoroalkyl-substituted olefins are classically accessed through multistep sequences or by cross-coupling of previously synthesized vinyl halides [6] or boronic acids [7] (Scheme 1). [9] However, for practical and economic reasons, such elaborate fluoroalkylating reagents are best avoided. [8] Such strategies have been successfully employed for the trifluoromethylation of alkynes with concomitant formation of a new CÀ C bond through cyclization.…”

“…Change of ligand to XPhos, a bulky, electron-rich monophosphine opened a route for the coupling of intermediate 2 with phenylstannane, but an incomplete conversion of phenylacetylene was observed, even after prolonged reaction time or with higher catalyst loading. Variously substituted arylacetylenes, bearing both electron-donating and electronwithdrawing substituents delivered the expected products (2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20) with satisfactory yields (40-90%). No formation of either 1 or 2 was noticed when the reactions were carried out in polar aprotic solvents, e. g. DMF (Table 1, Entry 9).…”

Visible Light Promoted Carbodifluoroalkylation of Homopropargylic Alcohols via Concomitant 1,4-Aryl Migration

“…最后, G 脱质子生成目标产物 2. 途径 b 中, 自由 基 B 转化为自由基 C [10] , 随后 C 被[fac-Ir(IV)(ppy) 3 ] ＋ 氧 化形成正离子 D, 最后脱质子生成副产物 3.…”