- Photoinduced Palladium-Catalyzed Negishi Cross-Couplings Enabled by the Visible-Light Absorption of Palladium–Zinc Complexes
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A visible-light-induced Negishi cross-coupling is enabled by the activation of a Pd0–Zn complex. With this photocatalytic method, the scope of deactivated aryl halides that can be employed in the Negishi coupling was significantly expanded. NMR experiments conducted in the presence and absence of light confirmed that the formation of the palladium–zinc complex is key for accelerating the oxidative addition step.
- Abdiaj, Irini,Huck, Lena,Mateo, José Miguel,de la Hoz, Antonio,Gomez, M. Victoria,Díaz-Ortiz, Angel,Alcázar, Jesús
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supporting information
p. 13231 - 13236
(2018/09/25)
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- C-C Activation by Retro-Aldol Reaction of Two β-Hydroxy Carbonyl Compounds: Synergy with Pd-Catalyzed Cross-Coupling to Access Mono-α-arylated Ketones and Esters
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A retro-aldol reaction of two β-hydroxy compounds in synergy with Pd-catalyzed cross-coupling of aryl halides is reported herein, which produces selectively mono-α-arylated ketones and esters in good yields. This reaction is compatible with a broad range of aryl iodides, bromides, chlorides, and triflates and can tolerate an array of functional groups on the aromatic ring. Ready scale-up of this reaction to gram level is applicable without an appreciable decrease in the reaction yield. Furthermore, concise syntheses of biologically active isocoumarin and indole derivatives have been achieved to greatly demonstrate the synthetic value of this retro-aldol reaction. Finally, the reaction mechanism has been discussed on the basis of experimental observations and DFT computational results. A regulated six-membered-ring transition structure has been located for the key retro-aldol C-C cleavage, which constitutes the rate-determining step of a full catalytic cycle. The concept of C-C activation by retro-aldol reaction may also find applications in other fundamental reactions.
- Zhang, Song-Lin,Yu, Ze-Long
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- THE REGIO- AND STEREOCHEMISTRY OF THE ALKOXIDE-INDUCED RING-OPENING OF METHOXYMETHYLIDENE-SUBSTITUTED HOMOPHTHALIC ANHYDRIDE
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Ring-opening of methoxymethylidene-substituted homophthalic anhydride (1) by methoxide occurs by two modes.Attack at the 1-position ("benzoate" carbonyl) leads to a stable acid-ester.A combination of unambiguous syntheses and 1H- and 13C-n.m.r. spectrosco
- Hutchings, Michael G.,Chippendale, A. Margaret,Ferguson, Ian
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p. 3727 - 3734
(2007/10/02)
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- PHOTOCHEMICAL RING OPENING REACTIONS OF 3-ALKOXYISOCOUMARIN AND 3-HALO-1-ISOQUINOLONE
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Irradiation of 3-methoxyisocoumarin (1) in an alcohol afforded two kinds of diester of homophthalic acid (3 and 4) and the mechanism including novel 1,5-sigmatropic methoxy rearrangement from initially formed ketene (5) to the isomeric ketene (6) was proposed.Similar photochemical ring opening reaction of 3-chloro- and -bromo-1-isoquinolones (8 and 9) as well as their novel photoalkoxylation reaction is also described.
- Kaneko, Chikara,Naito, Toshihiko,Miwa, Chiemi
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p. 2275 - 2278
(2007/10/02)
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