“…Interestingly, the temperature was found to be critical. The formation of 10 predominated and no formation of 9 was observed at the higher temperature (50 °C) in the presence of a large excess of TMSCl [47% (65%), 58% (68%), and 62% (68%) for 9a , 9b , and 9c , respectively; yields in parentheses were determined by 19 F NMR] . The silyl migration from oxygen to carbon was observed at the higher temperature.…”
Section: Resultsmentioning
confidence: 99%
“…In our previous communications, , we reported the one-pot syntheses of difluoroenol silyl ethers and β,β-difluoroenamines by electroreductive defluorination of trifluoromethyl ketones and imines, respectively. In this paper, we describe details of the selective electroreductive defluorination of trifluoromethyl ketones and trifluoroacetic acid derivatives, show the general applicability for the syntheses of β,β-difluoroketene silyl ( O,O-, O,S- , and O,N- ) acetals and 2,2-difluoro-2-trimethylsilyl acetates (Scheme ), and demonstrate the KF−CuI-promoted selective α-alkylation of the acetates. 1 …”
Difluoroenol silyl ethers 5 and 6, difluoroketene silyl (O,O-, O,S-, and O,N-) acetals 9 and 21, and 2,2-difluoro-2-trimethylsilylacetates 10 were prepared by electroreductive defluorination of trifluoromethyl ketones and trifluoroacetic acid derivatives in an MeCN-TBAB-chlorotrialkylsilane system using a carbon rod as an anode and a lead plate as a cathode. TBAF- or KF-CuI-promoted alpha-alkylation of 10 with electrophiles such as aldehydes, ketones, imine, acylhalides, and alkylhalides provided alpha-alkylated-alpha,alpha-difluoroacetates in good to excellent yields.
“…Interestingly, the temperature was found to be critical. The formation of 10 predominated and no formation of 9 was observed at the higher temperature (50 °C) in the presence of a large excess of TMSCl [47% (65%), 58% (68%), and 62% (68%) for 9a , 9b , and 9c , respectively; yields in parentheses were determined by 19 F NMR] . The silyl migration from oxygen to carbon was observed at the higher temperature.…”
Section: Resultsmentioning
confidence: 99%
“…In our previous communications, , we reported the one-pot syntheses of difluoroenol silyl ethers and β,β-difluoroenamines by electroreductive defluorination of trifluoromethyl ketones and imines, respectively. In this paper, we describe details of the selective electroreductive defluorination of trifluoromethyl ketones and trifluoroacetic acid derivatives, show the general applicability for the syntheses of β,β-difluoroketene silyl ( O,O-, O,S- , and O,N- ) acetals and 2,2-difluoro-2-trimethylsilyl acetates (Scheme ), and demonstrate the KF−CuI-promoted selective α-alkylation of the acetates. 1 …”
Difluoroenol silyl ethers 5 and 6, difluoroketene silyl (O,O-, O,S-, and O,N-) acetals 9 and 21, and 2,2-difluoro-2-trimethylsilylacetates 10 were prepared by electroreductive defluorination of trifluoromethyl ketones and trifluoroacetic acid derivatives in an MeCN-TBAB-chlorotrialkylsilane system using a carbon rod as an anode and a lead plate as a cathode. TBAF- or KF-CuI-promoted alpha-alkylation of 10 with electrophiles such as aldehydes, ketones, imine, acylhalides, and alkylhalides provided alpha-alkylated-alpha,alpha-difluoroacetates in good to excellent yields.
“…It is highly stable and has a chemical shift that (1) does not overlap with analyte components, (2) is sensitive to pH (>0.005 ppm/pH unit) in the pH range 6-8, and (3) tion of 98 using carbon rod as an anode and lead as a cathode in DMF provided difluorotrimethylsilyl acetate 99 as a major product [33]. Meanwhile, electrolysis of 100 using aluminum as an anode and stainless steel as a cathode in DMF gave the Claisen product 102 preferentially [34].…”
“…Electrochemical methods have hitherto been developed for reductive defluorination of a trifluoromethyl group (30), and they can be successfully applied to the preparation of difluoromethylene building blocks (31)(32)(33)(34)(35).…”
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