Synthesis of 1,4-benzothiazin-2-yl derivatives of 1,3-dicarbonyl compounds and benzothiazinone spiro derivatives by the reaction of 2-chloro-1,4-benzothiazin-3-ones with ‘push–pull’ enamines

Chemistry of Bridged Lactams and Related Heterocycles

“…346 Nazarenko proposed the intermediacy of bridged lactam 216 in the intramolecular condensation of 1,4-benzothiazin-3-one derivative 215 , ultimately affording the more stable 217 from the lactam viaintramolecular transacylation (Scheme 55). 347 Chibale reported the synthesis of tetracyclic bridged lactams based on thiolactone-isatin scaffolds (Table 6). 235 The X-ray structures of lactams 220c–220e indicated moderate distortions from planarity despite flexible ring systems ( 220c : τ = 10.4°; χ N = 5.1°; χ C = 0.7°; N–C(O) = 1.357 Å; C=O = 1.227 Å; 220d : τ = 5.3°; χ N = 1.1°; χ C = 3.0°; N–C(O) = 1.355 Å; C=O = 1.223 Å; 220e : τ = 0.6°; χ N = 8.9°; χ C = 4.5°; N–C(O) = 1.361 Å; C=O = 1.223 Å).…”

“…Waly found that a sequential treatment of N -acetylaminonitrile 211 with NaH and KO t -Bu afforded the bridged trione 212 (Scheme b), while Smet reported the synthesis of lactam 214 from 4-bromoisatin (Scheme c) . Nazarenko proposed the intermediacy of bridged lactam 216 in the intramolecular condensation of 1,4-benzothiazin-3-one derivative 215 , ultimately affording the more stable 217 from the lactam viaintramolecular transacylation (Scheme ) . Chibale reported the synthesis of tetracyclic bridged lactams based on thiolactone-isatin scaffolds (Table ) .…”

“…346 Nazarenko proposed the intermediacy of bridged lactam 216 in the intramolecular condensation of 1,4-benzothiazin-3-one derivative 215, ultimately affording the more stable 217 from the lactam viaintramolecular transacylation (Scheme 55). 347 Chibale reported the synthesis of tetracyclic bridged lactams based on thiolactone-isatin scaffolds (Table 6). 235 ring was formed in low yield (Scheme 56).…”