- Triple Mode of Alkylation with Ethyl Bromodifluoroacetate: N, or O-Difluoromethylation, N-Ethylation and S-(ethoxycarbonyl)difluoromethylation
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In this report, we have explored a triple mode of chemical reactivity of ethyl bromodifluoroacetate. Typically, bromodifluoroacetic acid has been used as a difluorocarbene precursor for difluoromethylation of soft nucleophiles. Here we have disclosed nucleophilicity and base dependent divergent chemical reactivity of ethyl bromodifluoroacetate. It furnishes lithium hydroxide and cesium carbonate promoted difluoromethylation of tosyl-protected aniline and electron-deficient phenols respectively. Interestingly, switching the base from lithium hydroxide to 4-N,N-dimethylamino pyridine (DMAP) tosyl-protected anilines afforded the corresponding N-ethylation product. Whereas, highly nucleophilic thiophenols furnished the corresponding S-carboethoxydifluoromethylation product via a rapid SN2 attack to the bromine atom prior to the ester hydrolysis. This mechanistic divergence was established through several control experiments. It was revealed that difluoromethylation reaction proceeds through a tandem in situ ester hydrolysis/decarboxylative-debrominative difluorocarbene formation and subsequent trapping by the soft nucleophile-NHTs or electron-deficient phenolic ?OH groups. In the presence of DMAP the hydrolysis of the ester is perturbed instead a nucleophilic attack at the ethyl moiety provides the N-ethylation product. Hence, besides the development of a practical base-promoted N-difluoromethylation of amines and electron-deficient phenols, divergent reactivity pattern of inexpensive and user-friendly ethyl bromodifluoroacetate has been explored. (Figure presented.).
- Polley, Arghya,Bairy, Gurupada,Das, Pritha,Jana, Ranjan
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supporting information
p. 4161 - 4167
(2018/09/21)
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- One-pot synthesis of (ethoxycarbonyl)difluoromethylthioethers from thiocyanate sodium and ethyl 2-(trimethylsilyl)-2,2-difluoroacetate (TMS-CF2CO2Et)
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An efficient one-pot cascade methodology for the synthesis of (ethoxycarbonyl)difluoromethyl thioethers is described. Benzyl, allyl, alkyl halides or diazonium salts as the starting materials together with thiocyanate sodium and TMS-CF2CO2Et in the presence of CsF or NaOAc afford a variety of the fluoroalkylthiolated products in moderate to good yields.
- Xu, Lijun,Wang, Hongyu,Zheng, Changwu,Zhao, Gang
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p. 6057 - 6066
(2017/09/23)
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- Aryl sulfuryl difluoroacetic salt compound, as well as preparation method and application thereof
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The invention discloses an aryl sulfuryl difluoroacetic salt compound, as well as a preparation method and application thereof. The aryl sulfuryl difluoroacetic salt compound reacts with aldehyde at room temperature to obtain an aryl sulfuryl substituted alpha-difluoromethyl alcohol compound. The aryl sulfuryl difluoroacetic salt compound has the beneficial effects of mild reaction condition, high product yield, few side effect and high universality when the aryl sulfuryl difluoroacetic salt compound is adopted to prepare the aryl sulfuryl substituted alpha-difluoromethyl alcohol compound.
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Paragraph 0024; 0025; 0032; 0033
(2017/08/10)
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- Facile synthesis of α,α-difluoroalkyl aryl thioethers and their oxidative desulfurization-fluorination to trifluorides
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Alkyl 2-arylthio-2,2-difluoroacetates are synthesized in 52-77% yield from alkyl 2-(arylthio)acetates via two succeeding fluoro-Pummerer rearrangements using the reagents combination of N-haloimides as electrophiles and excess Py·9HF as the fluoride source at room temperature. Subsequent treatment of the formed fluorinated thioethers with the same reagents at elevated temperature gave alkyl trifluoroacetates in almost quantitative yield under optimised conditions by oxidative desulfurization-fluorination.
- Hugenberg, Verena,Haufe, Günter
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experimental part
p. 942 - 950
(2010/10/02)
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