Thermische Cyclisierung von o‐Chlorarylisothiocyanaten

Abstract

Chlor vertauscht, so Iiiuft die Reaktion analog ab. Eine Besonderheit ist die Umsetzung von Trichloracetonitril (2'1, R1 = C1, mit Trichlormethylisocyaniddichlorid ( I ) , R = Cl; dabei entsteht unter Chlorabspaltung in 30-proz. Ausbeute das Tetrachlorpyrimidin (Fp %= 67 "C).

Development of an Efficient Process for 4,5,7-Trichloroquinoline, A Key Intermediate for Agrochemical Synthesis

“…The second route 1c (Scheme ) involves the reaction of 3,5-dichloroaniline ( 5 ) with ethoxymethylene malonic ester ( 11 ) in the first step. ,,4g The resulting anilinomethylene malonate of the formula ( 12 ) upon thermal cyclization in Dowtherm or diphenyl ether gives 4-hydroxy-3-carboxyquinoline derivative ( 13 ). The ester on hydrolysis gives the 4-hydroxyquinoline-3-carboxylic acid ( 14 ).…”

“…In view of these properties, it has created some interest among synthetic organic chemists, culminating in the development of several synthetic routes. 4a-i…”

Ring transformation of (4-chloro-5H-1,2,3-dithiazol-5-ylidene)acetonitriles to 3-haloisothiazole-5-carbonitriles

“…3,, Table 1, entry 5. Similar treatment of (Z)-2-bromo-2-(4-chloro-5H-1,2,3dithiazol-5-ylidene)acetonitrile ( 21 1448w, 1357w, 1317w, 1283s, 1148m, 912m, 822w, 806w, 783m; d C (125 MHz; CDCl 3 ) 141.7 (s), 133.4 (s), 121.8 (s), 108.8 (s); m/z (EI) 270 (M + + 4, 49%), 268 (M + + 2, 100), 266 (M + , 48), 189 (76), 187 (12), 163 (35), 161 (33), 137 (11), 113 (23), 111 (23), 108 (22), 82 (56); identical to an authentic sample. ; 1, entry 4.…”

Polychloroheteroaromatic Compounds

“…High yields (70-100%) of pentachlorobenzothiazole may be obtained by exhaustive chlorination of the parent heterocycle, its 2-sulphonic acid, 2-bromo-, 2-chloro-, or 2-mercapto-derivative with chlorine in the presence of antimony trichloride [674], or by the action of heat on pentachlorophenyl isothiocyanate [675]. Other polychlorobenzothiazoles ( Table 2.7) may be prepared by the action of heat on the corresponding polychlorophenyl isothiocyanate [675] .…”

“…Other polychlorobenzothiazoles ( Table 2.7) may be prepared by the action of heat on the corresponding polychlorophenyl isothiocyanate [675] . Thiocyanation of 3,4,5-trichloroaniline gives the phenyl thiocyanate (312) which cyclizes to 2-amino-5,6,7-trichlorobenzothiazole (313) [676].…”