Synthesis, properties and application of electronically-tuned tetraarylarsonium salts as phase transfer catalysts (PTC) for the synthesis of gem -difluorocyclopropanes

Nucleophilic Fluorination with Aqueous Bifluoride Solution: Effect of the Phase-Transfer Catalyst

“…Preparation of acyl fluorides in the presence of stoichiometric amount of water is unprecedented in chemical literature. Our observations shed a new light on behavior of the fluoride ions under phase transfer conditions, inspiring design and testing of more efficient fluoride carriers, e.g., based on reversible covalent binding of the anions. ,,, Studies toward development of environmentally benign fluorination protocols are presently ongoing in our laboratory.…”

“…Although Sharpless concluded that for synthesis of sulfonyl fluorides “phase transfer agents do not provide much benefit”, , his further observations with Wu on SuFEx-based polycondensation between bisalkylsulfonyl fluorides and bisphenol bis­( tert -butyldimethylsilyl)­ethers revealed that ammonium and phosphonium bifluorides display excellent catalytic activity as compared with inactive KHF 2 , AgHF 2 , and moderately active crown ether/KHF 2 system . For our studies we applied a set of tetraalkylammonium salts ( 1 – 5 ), tetraphenylarsonium chloride hydrochloride hydrate ( 6 ), and 18-crown-6 ( 7 ), as presented at Chart . The catalysts, used in 1 mol %, were tested in model reaction with 1-octanesulfonyl chloride, and results are shown at Figure .…”

The preparation and properties of 1,1-difluorocyclopropane derivatives

“…Chlorodifluoromethane as a source of difluorocarbene in the reaction: The advantage of using of tetraarylarsonium salts as effective phase-transfer catalysts for the two-phase reaction of chlorodifluoromethane (freon 22, 11 ) with α-methylstyrene ( 7 ) was demonstrated by Barbasiewicz [ 22 ] ( Scheme 6 ). The reaction proceeded at room temperature for 4 h with the formation of the cyclopropane derivative 8 .…”