- Tungsten-Catalyzed Transamidation of Tertiary Alkyl Amides
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Transamidation has recently emerged as a straightforward and convenient means to diversify amides. However, the kinetically and thermodynamically demanding transamidation of notoriously robust, fully alkyl-substituted tertiary amides still remains a longstanding challenge. Here, we describe a method for the activation of tertiary alkyl amides to streamline transamidation using simple tungsten(VI) chloride as a catalyst and chlorotrimethylsilane as an additive. The highly electrophilic and oxophilic tungsten catalyst enables the selective scission of a C-N bond of tertiary alkyl amides to effect transamidation of a myriad of structurally and electronically diverse tertiary alkyl amides and amines. Mechanistic study implies that the synergistic effect of the catalyst and the additive could pronouncedly induce the nucleophilic acyl substitution of tertiary alkyl amide with amine to realize transamidation.
- Feng, Fang-Fang,Liu, Xuan-Yu,Cheung, Chi Wai,Ma, Jun-An
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p. 7070 - 7079
(2021/06/30)
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- Combining Eosin y with Selectfluor: A Regioselective Brominating System for Para-Bromination of Aniline Derivatives
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A mild, metal-free, and absolutely para-selective bromination of aniline derivatives has been developed in excellent yields, wherein the organic dye Eosin Y is employed as the bromine source in company with Selectfluor. Neither air nor moisture sensitive, this facile reaction proceeds smoothly at room temperature and completes within a short time. Mechanistic studies indicate a radical pathway; therefore, the existence of an in situ generated brominating reagent, "Selectbrom", is postulated, which may reasonably account for the unique regioselectivity for the para-bromination of N-acyl- as well as N-sulfonylanilines.
- Huang, Binbin,Zhao, Yating,Yang, Chao,Gao, Yuan,Xia, Wujiong
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supporting information
p. 3799 - 3802
(2017/07/26)
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- Thiophenol-Catalyzed Visible-Light Photoredox Decarboxylative Couplings of N-(Acetoxy)phthalimides
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We have developed visible-light photoredox decarboxylative couplings of N-(acetoxy)phthalimides without an added photocatalyst in which simple and commercially available thiophenols are used as the effective organocatalysts, and 4-(trifluoromethyl)thiophenol shows optimal catalytic activity. Three representative decarboxylative examples were chosen including one amination and two C-C bond couplings to confirm efficacy of the visible-light photoredox reactions, and the results exhibited that they performed very well at room temperature. The interesting discovery should provide a novel and environmentally friendly strategy for visible-light photoredox transformation of organic molecules.
- Jin, Yunhe,Yang, Haijun,Fu, Hua
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supporting information
p. 6400 - 6403
(2016/12/23)
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- Charge-directed conjugate addition reactions of silylated α-β- unsaturated amidate anions
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A variety of N-substituted α-silylated-α,β-unsaturated amidate anions (2) have been found to be excellent Michael acceptors in charge-directed conjugate addition reactions with Grignard and organolithium reagents. The effects of olefin substitution, Si-substitution, N-substitution, and amidate counterion have been studied. Anionic acceptors may be prepared in situ by the addition of silylated vinyllithium reagents to isocyanates and then allowed to undergo conjugate addition reactions with subsequently added nucleophiles, but it was found to be more efficient to isolate neutral acceptors and regenerate the acceptor anion through the use of excess nucleophile. β-Substituted acceptors were found to react only with reactive organolithium reagents while a β,β-disubstituted acceptor failed to undergo conjugate addition reactions. A primary amide acceptor (14d) also undergoes addition reactions with larger quantitites of nucleophiles suggesting that dianionic amidate acceptors (31) are involved. Diene acceptor 24 was found to undergo a 1,6-addition reaction with n-BuLi. Sodium and potassium amidate salts were found to be inferior to lithium and magnesium salts in addition reactions in keeping with the expectation that an increase in carbonyl-group charge burden retards conjugate reactions. Triphenylsilyl-containing acceptor 16 was found to be more reactive in reactions with n-BuMgCl but less reactive with bulkier tert-BuMgCl. Adduct dianions can be monoalkylated with alkyl iodides and used in Peterson olefination reactions.
- Cooke Jr.,Pollock
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p. 7474 - 7481
(2007/10/02)
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