Preparation of Alkyl and Aryl Chlorodifluoromethyl Ethers Using BrF₃

Abstract

Both alkyl and aryl chlorothioformates could readily be obtained from the corresponding alcohols and thiophosgene. These families of compounds were treated with BrF 3 to form the corresponding alkyl and aryl chlorodifluoromethyl ethers in 60-85 % yields. The method is suitable for constructing

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“…– is relatively stable and easily formed, a reaction of radical nature with tributyltin hydride was eventually found to be the best. Indeed most chlorodifluoro ethers when treated with Bu 3 SnH and 1,1′‐azobis(cyclohexane‐carbonitrile) (ABCN) in dry THF for two hours, resulted in difluoromethyl ethers 137 with yields higher than 80% (Scheme ) 86,87…”

Recent synthetic methods towards the –OCHF2 moiety

“…Rozen et al [46,47] described a general route using commercially available thiophosgene and BrF3 to access the -OCHF2 moiety. The process started with the conversion of an alcohol to the corresponding chlorothioformate, whose C=S bond was fluorinated by the uneasy to handle agent BrF3, to give difluorochloromethyl ethers.…”

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“…Indeed most chlorodifluoro ethers when treated with Bu 3 SnH and 1,1'-azobis(cyclohexane-carbonitrile) (ABCN) in dry THF for two hours, resulted in difluoromethyl ethers 137 with yields higher than 80% (Scheme 32). [86,87] There are only a few reactions designed for constructing compounds containing the difluoro diether (OCF 2 O) group. Aromatic derivatives of this type have been prepared mainly by reacting various reagents with nucleophilic fluorides (e.g., HF, AgF, SbF 3 Bu 4 NH 2 F 3 ) with either dichlorodioxomethylene derivatives or thiocarbonates.…”