Different Behaviors of a Cu Catalyst in Amine Solvents: Controlling N and O Reactivities of Amide

Yamane, Yoshio; Miyazaki, Koichiro; Noji, Takashi

doi:10.1021/acscatal.6b02309

Cited by 41 publications

(16 citation statements)

References 36 publications

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“…Moreover, Nishikata has published a series of papers on the Cu‐catalyzed reactions between α‐bromo esters/amides and olefins since 2013, which are consistent with our publications on the Ni‐catalyzed reactions between α‐bromo esters/amides and olefins . In their recent publication on the selective formation of lactam or iminolactone from the reaction between α‐bromo amides and electron‐deficient olefins, they mentioned that: “Conversely, the intermediate B under weakly basic conditions undergoes radical cyclization to produce E . According to previous reports, amide oxygens favorably react with carbocations.…”

Section: Methodssupporting

confidence: 80%

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Reply to Correspondence on “Carbon‐Centered Radical Addition to O=C of Amides or Esters as a Route to C−O Bond Formations”

Liu

Lei

2019

Chemistry A European J

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Refer to the correspondence from Prof. Metzger about our previous publication on "Carbon-Centered Radical Addition to O=Co fA mides or Esters as aR oute to CÀOB ondF ormations", we wouldl ike to express some of our understandings herein.We mentionedi no ur paper that "Another possibility is CÀO bond formation through carbon-centered radical addition to carbonyl groups,i nw hich an ew carbon-centered radicali s generated( Scheme 1, Path B). There are relativelyf ew reports on the latter case of radical addition process, in which only aldehydea nd ketone have been applied as the carbonyl source [Eq. (1)]." [1] Theser eports suggested the possibility of CÀO bond forming through carbon-centered radical addition to aldehydec arbonylg roups. Furthermore, Kende et al. reported an abnormalp hoto-Fries rearrangement reactiono fa ryl phthalantes,i nw hich ac arbon-centered radical addition to carbonyl group of esters was suggested (Scheme 1). [2] Although Eguchi et al. have calculated that the cyclization in the conjugated system might be due to the conjugation effect with an onradical cyclization mechanism,t he addition of carbon-centered radicalt ocarbonyl groupi nanon-conjugateds ystem has not been ruled out. [3] In 1964, Menapace et al. demonstrateda na lkyl radicala ddition to the carbonyl of ketone to generate at etrahydrofuran derivative( Scheme2), suggesting that ac arbon-centeredr adi-cal addition to the ketone carbonyl group to form CÀOb ond is possible. [4] Moreover,N ishikatah as published as eries of papers on the Cu-catalyzed reactions between a-bromoe sters/amides and olefinss ince 2013, [5] whicha re consistent with our publications on the Ni-catalyzed reactionsb etween a-bromoe sters/amides and olefins. [1,6] In their recentp ublication on the selective formationo fl actam or iminolactone from the reaction between a-bromoa mides and electron-deficient olefins, [5c] they mentionedthat:" Conversely,t he intermediate B under weakly basic conditions undergoes radical cyclization to produce E. According to previousr eports,a mide oxygens favorably react with carbocations. However,t he generation of an a-carbocation from B by oxidation with aC u II species is considered to be unfavorable due to stability issues. Therefore,t he addition of a carbon-centered radicals pecies to ac arbonyl group is another reactionp athway and is at ypical radicalr eaction. Finally,i minolactone 4 is obtained after the oxidation of E with Cu II followedb yp rotonelimination" (Scheme3). [5c] Our cyclizationpaper was cited to explaint heir experimental observations. Furthermore, there is ac ommenti nt he correspondence of Prof. Metzgert hat "Amazingly,t he same authors reported in 2012 on the addition of the same or similar a-bromo esters and amides to the same or similar styrenes yielding 3-unsaturated esters and amides using the same catalyst and very similar reactionc onditions to those given in Scheme 2w ithout step 2a si nr eactions( 2) and (3)-namelyw ithout heatingt he reactionm ixture with acid and water."T his commenti su n...

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Section: Methodssupporting

confidence: 80%

“…Therefore, the addition of a carbon‐centered radical species to a carbonyl group is another reaction pathway and is a typical radical reaction. Finally, iminolactone 4 is obtained after the oxidation of E with Cu II followed by proton elimination” (Scheme ) …”

Section: Methodsmentioning

confidence: 99%

Reply to Correspondence on “Carbon‐Centered Radical Addition to O=C of Amides or Esters as a Route to C−O Bond Formations”

Liu

Lei

2019

Chemistry A European J

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“…The mechanism proposed for the radical cascade process follows the one by Nishikata et al . shown in Scheme …”

Section: α‐Haloamides As a Three‐atom Unit For Concise Synthesis Of Hmentioning

confidence: 99%

“…Nishikata and co‐workers succeded in the annulation reaction of acrylates B with α‐bromoamides A by using a catalyst consisting of Cu(I)‐TPMA in the presence of BnBu 3 NBr (probably increasing the catalyst solubility) (Scheme ).…”

Section: α‐Haloamides As a Three‐atom Unit For Concise Synthesis Of Hmentioning

confidence: 99%

The Fascinating Chemistry of α‐Haloamides

et al. 2020

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The aim of this review is to highlight the rich chemistry of α‐haloamides originally mainly used to discover new C−N, C−O and C−S bond forming reactions, and later widely employed in C−C cross‐coupling reactions with C(sp3), C(sp2) and C(sp) coupling partners. Radical‐mediated transformations of α‐haloamides bearing a suitable located unsaturated bond has proven to be a straightforward alternative to access diverse cyclic compounds by means of either radical initiators, transition metal redox catalysis or visible light photoredox catalysis. On the other hand, cycloadditions with α‐halohydroxamate‐based azaoxyallyl cations have garnered significant attention. Moreover, in view of the important role in life and materials science of difluoroalkylated compounds, a wide range of catalysts has been developed for the efficient incorporation of difluoroacetamido moieties into activated as well as unactivated substrates.

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“…Interestingly, another Cu(I)-catalyzed reaction from αhaloacetamides 1 mostly with acrylamides (EWG = amide function) or acrylic esters (EWG = ester function) 79 was developed by Nishikata and co-workers (Scheme 30). 105 The authors managed to fully control the N-vs O-cyclization of the amide function of αhaloacetamides 1 depending on the base, the source of copper (CuBr.Me 2 S vs CuI), the ligand used and the presence of an ammonium salt, leading selectively to -lactams 80 or to the corresponding iminolactones 81. Remarkably, it proved possible to totally control the course of the domino process by tuning the reaction conditions and the desired heterocyclic systems 80 or 81 were isolated in good to high yields.…”

Section: Scheme 29 Formation Of Benzoxazin-3-onesmentioning

confidence: 99%

α-Halogenoacetamides: versatile and efficient tools for the synthesis of complex aza-heterocycles

2019

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Different Behaviors of a Cu Catalyst in Amine Solvents: Controlling N and O Reactivities of Amide

Cited by 41 publications

References 36 publications

Reply to Correspondence on “Carbon‐Centered Radical Addition to O=C of Amides or Esters as a Route to C−O Bond Formations”

Reply to Correspondence on “Carbon‐Centered Radical Addition to O=C of Amides or Esters as a Route to C−O Bond Formations”

The Fascinating Chemistry of α‐Haloamides

α-Halogenoacetamides: versatile and efficient tools for the synthesis of complex aza-heterocycles

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