The pyrolysis of 1,3,4,5,6,7,8-heptafluoro-2-naphthyl propynoate: remarkable products obtained via an internal Diels?Alder reaction

Flash vacuum pyrolysis of the ester 1,3,4,5,6,7,8-heptafluoro-2-naphthyl propynoate (6) at 550 degrees C/0.01 mmHg gave three products: 3 and 4 by an overall decarbonylation reaction. and 5 by a further decarbonylation of 3 and/or 4. Isomerisation of 6 to 2-fluoropropynyl 2-naphthoate 8 by a Diels-Alder/retro-Diels-Alder sequence followed by decarbonylation and a series of 1,2-fluorine shifts offers a rationalisation for the formation of the products.