Preparation of trifluoromethyl and other perfluoroalkyl compounds with (perfluoroalkyl)trimethylsilanes

Abstract

The preparation of a variety of novel perfluoroalkyl-substituted compounds in high yields using easily prepared (perfluoroalky1)trimethylsilanes (la-c) is described. (Trifluoromethy1)-, (pentafluoroethy1)-, and (heptafluoropropyl)trimethylsilane, la-c, respectively, react readily with carbonyl compounds, such as aldehydes and ketones, by a fluoride-initiated catalytic process. Fluoride-initiated addition of 1 to a carbonyl group generates an oxyanionic species which then further catalyzes the reaction. Even enolizable carbonyl compounds react cleanly under the reaction conditions. A study of the scope of the reactivity of la toward other carbonyl groups in esters, lactones and an acid chloride was also carried out. Thus la reacts cleanly with five-and six-membered ring lactones.However, unactivated esters do not react under the reaction conditions. The acid chloride reacts with la to give a mixture of products.

o‐Nitrobenzyl Photolabile Protecting Groups with Red‐Shifted Absorption: Syntheses and Uncaging Cross‐Sections for One‐ and Two‐Photon Excitation

“…2,2,2-Trifluoro-1-(4,5-dimethoxy-2-nitrophenyl)ethanol 4 Fa and hydroxy(4,5-dimethoxy-2-nitrophenyl)acetonitrile 4 CNa were prepared by reaction of 4,5-dimethoxy-2-nitrobenzaldehyde with (trifluoromethyl) trimethylsilane [36] and trimethylsilane cyanide, respectively, in THF in 80 and 90 % yield. Condensation of chloroform on 4,5-dimethoxy-2-nitrobenzaldehyde in the presence of 1,…”

Synthesis of gem‐Difluorinated Cyclopropanes and Cyclopropenes: Trifluoromethyltrimethylsilane as a Difluorocarbene Source

“…[17] Importantly, TMSCF 3 can be used as a trifluoromethyl anion source at low temperatures, and the decomposition of the trifluoromethyl anion to difluorocarbene and a fluoride ion at low temperatures was recognized as a side decomposition reaction. [18] Based on this background, we studied the cyclopropanation reaction of alkenes with TMSCF 3 at low temperatures using nonmetallic fluoride sources as initiators. Additionally, we found that TMSCF 3 can be easily activated even at room and/or higher temperatures, and we explored reactions of this reagent with alkenes and even alkynes at 65 8C under iodide-based activation.…”

A General Route to Perfluoroalkyl‐ and Trifluorovinyl‐Substituted Fischer Carbene Complexes of Tungsten and Chromium – Syntheses, Characterisation and Structures

“…Solvents were purified by reported methods. [21] [Me 4 N]F, [22] Me 3 SiCF=CF 2 [23] and Me 3 SiC 2 F 5 [24] were synthesised following literature procedures.…”