Fluorinated Ketene Dithioacetals. Part 10. Synthesis of New Perfluorinated (2H)-Pyridazin-3-ones and 3-(Alkyl- or Arylamino) Substituted Pyridazines

Abstract

Fluorinated Ketene Dithioacetals. Part 10. Synthesis of New Perfluorinated (2H)-Pyridazin-3-ones and 3-(Alkyl-or Arylamino) Substituted Pyridazines S y n t h e s i s o f N e w P e r f l u o r i n a t e d ( 2 H ) -P y r i d a z i n -3 -o n e s a n d 3 -( A l k y l -o r A r y l a m i n o ) S u b s t i t u t e d P y r i d a z i n e s Abstract: α-Trifluoromethyl γ-keto thiolesters 4a and 7, obtained from the corresponding perfluoroketene dithioacetals 3a, led in a two-step sequence (condensation with hydrazine -dehydrogenation reaction) to the (2H)-pyridazin-3-ones 9a,c-e. Subsequent chlorination and substitution with amines led to 3-(alkyl-or arylamino)-4trifluoromethyl pyridazines 11a-d. The higher homologue, the αpentafluoroethyl γ-keto thiolester 4b, reacted similarly, but a subsequent HF elimination allowed direct access to 4-tetrafluoroethyl pyridazin-3-ones 13b,c.