Selective Electrosynthesis of (Trimethylsilyldifluoro)methylbenzene, a PhCF2- Precursor; Conditions for a Molar Scale Preparation without HMPA

Abstract

Electrochemical reductive silylation of trifluoromethylbenzene by the sacrificial anode technique selectively led, in a THF/ DMPU mixture instead of THF/HMPA and according to the charge passed, to the corresponding mono-, bis-or tris-trimethylsilyl derivatives, respectively PhCF 2 TMS, PhCF(TMS) 2 and PhC(TMS) 3 . This reaction, without any chemical equivalent, was extended to a molar scale synthesis, using a tubular flow cell.

Desymmetrization of Cyclohexa-1,4-dienes − A Straightforward Route to Cyclic and Acyclic Polyhydroxylated Systems

“…Moreover, we did not observe any desilylation,12 which may occasionally occur under the basic conditions of the Birch reduction. Finally, through the use of a tubular flow cell, we were able to extend the method to a large‐scale preparative reduction of 5f (Entry 13, conditions C) 14. Under these conditions, up to 20 g of mesitylene 5f could be reproducibly transformed into 6f in very high yield.…”

Functionalized fluoroalkyl and alkenyl silanes: Preparations, reactions, and synthetic applications

“…A mixed solvent of THF-DMPU is usable instead of THF-HMPA for the purpose although the yield is low (76% of 112). In contrast, reduction with metals was less effective since no reduction of 114 occurred with magnesium, while over reduction of 114 to a,a,a-trisilyl toluene 116 (67%) was predominant with metal lithium in THF [41]. Likewise, chlorodifluoromethyl ether 117 was transformed to difluorosilane 118 by magnesium reduction in DMF [24].…”

“…Electroreduction could achieve selective monosilylation [41]. The desired silane 112 was prepared in 92% yield by electroreduction of 114 in a mixture of THF and HMPA using a sacrificial aluminum anode and stainless steel grid as a cathode in an undivided cell.…”

“…The desired silane 112 was prepared in 92% yield by electroreduction of 114 in a mixture of THF and HMPA using a sacrificial aluminum anode and stainless steel grid as a cathode in an undivided cell. Benzylic fluorines were successively replaced with trimethylsilyl group depending on the amount of electricity; monosilyl 112, disilyl 115, and trisilyl 116 were obtained in 92%, 83%, and 65% yields when 2.1, 4.3, and 6.3 F/mol of electricity were passed, respectively (Scheme 28) [41]. A mixed solvent of THF-DMPU is usable instead of THF-HMPA for the purpose although the yield is low (76% of 112).…”

Recent Advances in Fluoride Ion Activation of Silicon Bonds in Organic Synthesis

“…81]. Similar addition reactions of fluorinated silanes to carbonyl compounds readily proceed also in the presence of Bu 4 NF / THF[82] and Bu 4 NF / dimethoxyethane[83], Tetrabutylammonium fluoride mediated reactions of 1-trimethylsilyl-2,2-difluorocyclopropane derivatives 153 with aldehydes provide a good route to fluorinated cyclopropylcarbinols 154 (Scheme 53). The formation of products 154 proceeds via intermediates -difluorocyclopropyl anions[84],…”