Perfluoroacetylenephosphonates in Diels–Alder reactions: Synthesis of perfluoroalkylated heterocyclic and carbocyclic phosphonates

Diels–Alder Reaction in the Synthesis of Fluorinated (Hetero)Aromatic Compounds

“…Röschenthaler and Tverdomed synthesized a series of alkynyl phosphonates 292 and studied their Diels–Alder reactions , . Among others, the reaction with 2,3‐dimethyl‐buta‐1,3‐diene was used to prepare aromatic phosphonates 294 by sequential [4+2]‐cycloaddition/oxidative aromatization.…”

3‐Trifloxy‐3‐(trifluoromethyl)prop‐2‐ene 1‐Iminium Salts as Precursors for Elusive 3‐(Trifluoromethyl)prop‐2‐yne 1‐Iminium Salts

“…Only a few other CF 3 -dibenzobarrelenes have been reported so far. [17,22,23] The excellent dienophilic reactivity of 3-CF 3 -propyniminium salts 2 becomes evident by comparison with data reported for Diels-Alder reactions of anthracene and some other electrophilic dienophiles (Table 2). As many Diels-Alder reactions [a] See Scheme 5; iminium-substituted Diels-Alder adducts 10 were transformed without isolation (i. e., an equimolar amount of by-product HN + Et 3 TfO À was present in the reaction mixture) into neutral products 11-14. involving anthracene require strong thermal activation, it represents kind of a benchmark diene to assess the reactivity of different dienophiles.…”

“…Only a few other CF 3 -dibenzobarrelenes have been reported so far. [17,22,23] The excellent dienophilic reactivity of 3-CF 3 -propyniminium salts 2 becomes evident by comparison with data reported for Diels-Alder reactions of anthracene and some other electrophilic dienophiles (Table 2). As many Diels-Alder reactions Table 1.…”

“…Thus, both a vacuum thermolysis (e. g., 120 °C/0.07 mbar, 15 min for 5 b) and the reaction with triethylamine or other tertiary amines generated a mixture of unknown fluorine-containing species, as indicated by several new 19 F NMR signals. In the mixture obtained from vacuum thermolysis, a prominent 19 F NMR signal at δ(CDCl 3 ) = À 52.0 ppm at least pointed to the presence of the desired acetylenic iminium salt 2 (compare: δ F = À 52.3 ppm for CF 3 À C�CÀ COOEt [16] and À 53.87 ppm for CF 3 À C�CÀ PO(OEt) 2 [17] ). Workup of these mixtures was unpromising in view of the anticipated high reactivity of alkynes 2 and the difficulty to separate a mixture of ionic and potentially hydrolytically labile products.…”

Catalyst-free synthesis of cycloalkenyl phosphonates

“…6 The reaction was conducted in a sealed ampoule with diene as a solvent and 1,4-hydroquinone as a polymerization inhibitor at 140-145 C under nitrogen for 5 h. In the same year, they developed a new methodology for synthesis 1,2-peruoroalkyl vinylphosphonates, based on the Diels-Alder reactions of peruoroacetylenephosphonates with different dienes. 7 However, these synthetic methods have limited scope. Our continued interest in the reactivity of alkynyl phosphonates 8 and P-C bond formations 9 recently prompted us to explore a more atom-economical and functional group tolerance method for the synthesis of cycloalkenyl phosphonates.…”