Reactions of Perfluoro-2-methyl-2-pentene with Carboxylic Acids, Alcohols, and Some Cyclic Amides. A New Fluorinating Reagent

Article abstract of DOI:10.1246/bcsj.54.1151

Perfluoro-2-methyl-2-pentene (PMP) reacts with carboxylic acids, alcohols, and 2-pyridone, giving Michael-type addition products, 1,1,1,3,4,4,5,5,5-nonafluoro-2-trifluoromethyl-3-acyloxypentane, 1,1,1,3,4,4,5,5,5-nonafluoro-2-trifluoromethyl-3-alkoxypentane, 1,1,1,3,4,4,5,5,5-nonafluoro-2-trifluoromethyl-3(2-pyridyloxy)pentane, respectively, in good yields.In the presence of bases, carboxylic acids give acid fluorides, 1,1,1,4,4,5,5,5-octafluoro-2-trifluoromethyl-3-pentanone, and 1,1,1,4,4,5,5,5-octafluoro-2-trifluoromethyl-3-acyloxy-2-pentene (4), the yields changing with base, solvent, phase-transfer catalyst, and their combination.In the presence of triethylamine, fluorination occurs exclusively, producing acid fluorides in good yields.Alcohols and 2-pyridone are converted into alkyl fluorides and 2-fluoropyridine, respectively, with use of triethylamine as a base with an aprotic solvent.The reaction of PMP with 4-pyridone and 6-chloro-2-ethyl-5-methyl-4(3H)-pyrimidone were also examined.The fluorination reactions were rationalized by preferential replacement of the vinylic fluorine of PMP and a good leaving function of the perfluoro enol group of the intermediates such as 4.