1,1'-Thiocarbonyldiimidazole → 1-(5-Chloro-2-methyl-phenyl)-3-ethyl-3,4,5,6-tetrahydro-pyrimidine-2(1H)-thione

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Reaction Steps

A solution of the diamine of Step A (7.1 g) in dioxane (250 mL) and 1,1′-thiocarbonyldiimidazole (5.6 g) was refluxed under nitrogen for 2.5 hrs. Following the addition of para-toluenesulfonic acid monohydrate (11.9 g), the reaction mixture was heated at reflux for 48 hrs. The reaction was cooled and filtered and the filtrate was concentrated in vacuo to give a brown oil. The crude material was dissolved in dichloromethane and absorbed onto a column of Merck-60 flash silica gel. Elution with 20% ethyl acetate in hexane provided a brown solid which was triturated with diethyl ether to give the title product (2.1 g, 25.0%) as a white solid, m.p. 111-112° C.

Provenance & Evidence