Mg0-promoted selective C–F bond cleavage of trifluoromethyl ketones: a convenient method for the synthesis of 2,2-difluoro enol silanes

Abstract

2,2-Difluoro enol silyl ethers were readily prepared by Mg 0 promoted selective defluorination of trifluoromethyl ketones in the presence of TMSCl, which involves C-F bond cleavage.

Expedient synthesis of [18F]‐labeled α‐trifluoromethyl ketones

“…Compounds 1a-d were prepared following the literature method 12 and modified in our laboratory. 13 All compounds were identified by 1 H and 19 F NMR spectroscopy and mass spectrometry, and found to be consistent with the literature data.…”

“…All these 2,2-difluoro silyl enol ethers (1a-d) were prepared from the respective ketones via magnesium metal mediated reductive defluorination following a literature procedure, 12,13 and a representative method is described. To a dry 250 ml Schlenk flask was added magnesium turnings (1.45 g, 60 mmol), dry tetrahydrofuran (THF, 120 ml) and chlorotrimethylsilane (TMSCl, 13.0 g, 120 mmol), and the flask was cooled down to 08C.…”

“…Spectroscopic data were consistent with the literature. 12 Compounds 1b-d were also characterized by 1 H and 19 F NMR spectroscopy and mass spectrometry.…”

Direct Aldol–Reduction Process using Difluoromethyl Aryl Ketones and Aryl Aldehydes in the Presence of Potassium tert‐Butoxide: One‐Pot Efficient Stereoselective Synthesis of Symmetrical and Unsymmetrical anti‐2,2‐Difluoropropane‐1,3‐diols

“…[13] Our new method potentially offers the advantage of preparing both symmetrical and unsymmetrical diols in one step, in a diastereoselective manner, from readily available difluoromethylaryl(heterocyclic) ketones. [8,14,15] Thus it was decided to explore the generality of the reaction, using the less complex difluoromethyl phenyl ketone 5 [14] in its reactions with benzaldehyde 2 and other p-substituted aryl aldehydes 6-10. The preliminary results from this study are presented below.…”

Diastereoselective Alkylation of Glycinates by Assistance of Intramolecular Potassium⋅⋅⋅Fluorine Interactions

“…To this end, treatment of the benzylimine of 1 d (n = 3) [4] with DBU efficiently catalyzed isomerization through a [1,3] proton shift as reported by Soloshonok et al [4,5] Product 2 d was furnished upon hydrolytic workup. On the other hand, syntheses of 2 b (n = 1) and 2 c (n = 2) were initiated by the similar imine process from the corresponding ketones (1 b, n = 1 and 1 c, n = 2, respectively) [6] , and their NaBH 4 -mediated reduction followed by regiose- [a] Prof. …”