Thermal Diels–Alder Reactions of 3‐(Benzoylamino)‐6‐(polyfluoroalkyl)pyran‐2‐ones – New Synthesis of p‐(Polyfluoroalkyl)anilines

Abstract

A new practical method for the regioselective synthesis of the N-benzoyl-4-(polyfluoroalkyl)anilines 5a-g by thermal Diels-Alder cycloaddition of 5-substituted 3-(benzoylamino)-6-(polyfluoroalkyl)pyran-2-ones 1a-e with fluorostyrenes 2 and 7, acetylenes 8a-c or vinyl ethers 10 and 13a and 13b is described. In the case of the reactions of pyrone 1a with cy-

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

“…We have shown that 3‐benzoylamino‐(6‐polyfluoroalkyl)‐2‐pyrones 29 can be also convenient dienes in Diels–Alder reaction . Pyrones 29 are easily accessible by reaction of the corresponding enones 27 with N ‐benzoyl glycine by Erlenmeyer‐Plöchl reaction through intermediates 28 (Scheme ) …”

Diels–Alder Reaction of Ethyl 3‐Benzamido‐2‐oxo‐6‐(trifluoromethyl)‐2H‐pyran‐5‐carboxylate with Alkoxyalkenes as an Effective Approach to Trifluoromethyl‐Containing 3‐Aminobenzoic Acid Derivatives

“…Nonfluorinated cyclohexa‐1,3‐dienes similar to compound 9 were recently investigated by Kočevar and co‐workers,8 who were also faced with their low stability and aromatization during column chromatography. The more stable bicyclic cyclohexa‐1,3‐dienes 5 were formed from the reaction with pyrone 1 (see Scheme ) 2b…”

“…Aryl ethyl ether 11 was separated from compound 10 by column chromatography and isolated in 56 % yield (based on pyrone 2 ). It is worth noting that upon reaction of pyrone 1 with ethyl vinyl ether, neither bicyclic adducts analogous to 8 nor cyclohexa‐1,3‐diene derivatives analogous to 9 were isolated 2b…”

“…In addition to our earlier investigations of [4+2] cycloaddition reactions of fluorinated compounds,3 we have described the synthesis of 3‐benzamido‐6‐(trifluoromethyl)‐2 H ‐pyran‐2‐ones 1 – 3 from readily available β‐alkoxy enones4 and the Diels–Alder reactions2b of 1 – 3 with various dienophiles to lead to compounds 4 – 6 (see Scheme ).…”

Synthesis of New δ‐(Polyfluoroalkyl)‐δ‐hydroxy‐α‐amino Acids

“…We have previously reported the synthesis [9] and reactivities [9,10] of pyrones 3, which in this paper have served as convenient precursors of the target amino acids 1 and 2. The pyrones 3 have the same carbon skeletons and necessary functional groups.…”