The Synthesis of Fluorinated 4H-1,4-Benzothiazine-2-carboxylic Acid 1,1-Dioxides—Thionated Analogues of Pefloxacin

Fluoroarenes in the synthesis of benzoannulated nitrogen-containing heterocycles

“…Alkylation of the latter with methyl bromoacetate in ethanol followed by condensation of intermediate 40 with triethyl orthoformate yields 6,7 difluoro 2 methoxycarbonyl 4H 1,4 benzothiazine 1,1 dioxide (41) (Scheme 17). 39 Ammonolysis of sulfonyl chloride 38 gives sulfon amide 42; its cyclization with triethyl orthoformate or ethyl oxalate affords 1,2,4 benzothiadiazines 43 and 44 (Scheme 18). 40…”

Fluorinated benzazoles and benzazines

“…Thioanalogs of pefloxacin, fluorinated 4H-1,4-benzothiazin-1,1-dioxides 75, and 1,4-benzothiadiazine-1,1-dioxides 76 have been prepared by using 2-amino-4,5-difluorobenzene sulfone derivatives 74 (Scheme 23) [66,67]. An alternative cyclization of acrylates 77a leads to pyrazoles [74].…”