Perfluoroketene dithioacetals and perfluorodithiocarboxylic acid derivatives: Versatile tools for organofluorine synthesis

Abstract

Perfluoroketene dithioacetals are simple and versatile compounds that can be transformed into a large variety of trifluoromethyl derivatives, in particular aza‐ and thiaheterocycles, perhalodithiocrotonic esters, and fluorinated dithiol thiones. These unsaturated perfluorodithioesters and analogs give interesting polar cycloaddition reactions whose mechanism is strongly influenced by the fluorine substitution. This substitution plays an important role in the reactivity of saturated perfluorodithiocarboxylic acids as well. Except for the carbophilic addition of allyl Grignard reagents to perfluorocarboxamides, a domino thiophilic addition‐fluoride elimination was the main reaction process. Interestingly, a three‐step domino reaction occurs when pentafluorodithioesters are treated with allyl Grignard reagents, the third step being an effective σ[3,3] rearrangement, so that the overall reaction is a formal substitution of an allyl group for the α‐fluorine atom. 2,2‐Bis(allyl)‐3,3,3‐trifluorodithiopropanoates were prepared by performing this domino reaction twice, in a possible one‐pot procedure. © 2007 Wiley Periodicals, Inc. 18:500–508, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20346

Domino nucleophilic trifluoromethylations of alkyl perfluorodithioesters

“…The chemistries of perfluoroesters and perfluoroketene dithioacetals are closely related [1]. Due to the electronegativity of fluorine and perfluoralkyl groups, alkyl perfluorodithioesters and analogues react with various nucleophiles at sulfur of the thiocarbonyl group (''thiophilic attack'') with subsequent belimination of a fluoride.…”

“…Red oil, bp 85 8C (0.8 mbar) 1. H NMR (CDCl 3 ): d 7.29 m (5H, Ph), 3.53 t (2H, CH 2 , 3 J HH 7.6 Hz), 3.00 t (2H, CH 2 , 3 J HH 7.6 Hz).…”

Synthesis of (2,2,2-trifluoroethyl) substituted pyridazin-3(2H)-ones and 1,5-dihydropyrrol-2-ones from α,β-unsaturated γ-lactones and hydrazines

“…To the best of our knowledge, there are no examples of a pyridazin-3(2H)-one bearing such substituents in the literature. g-Ketothioester 8 was prepared according to our reported procedure [19] starting from the corresponding perfluoroketene dithioacetal [20,21]. The treatment of 8 with non-nucleophilic diisopropylamine in diethyl ether led to a,b-unsaturated glactone 6a as a mixture of stereomers [19].…”

Fluorine chemistry in Ukraine

“…In another research direction of this group, chemical properties of polyfluoroalkyldithiocarboxilates received a particular attention. A critical influence of fluorine-containing alkyl substituent on the [3 + 2]-and [2 + 4]-cycloaddition reactions of these compounds was demonstrated [23].…”