Lawesson's reagent → 7-Chloro-2-(2-chloroethyl)-2,3-dihydro-4-methylpyrido[3,2-f][1,4]oxazepin-5(4H)thione

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Reaction Steps

7-Chloro-2-(2-chloroethyl)-2,3-dihydro-4-methylpyrido [3,2-f][1,4]oxazepin-5(4H)-one, 6.0 g (0.022 mole) was suspended in 200 ml of toluene. To this suspension was added 2,4-bis(4-methoxyphenyl)-1,3-dithia-2,4-diphosphetane-2,4-dilsulfide. The mixture was heated to reflux with vigorous stirring for 2 hours. Because the reaction was not complete, an additional amount (3.0 g) of 2,4-bis(4-methoxyphenyl)-1,3-dithia-2,4-diphosphetane-2,4-disulfide was added and the mixture stirred at reflux for 2 hr and left standing for 56 hr at room temperature. The toluene layer was decanted and washed with 50 ml of dilute aqueous sodium hydroxide and 50 ml of dilute hydrochloric acid. Toluene was removed by rotary evaporation (~80° C., water aspirator). The crude oil was recrystallized from isopropyl alcohol giving 3.5 g (54%) of pale yellow crystals, m.p. 125°-127° C.

Provenance & Evidence