1,3-Dibutyl-5-[1,3]dithian-2-ylidene-pyriMidine-2,4,6-trione synthesis

Yield:1313712-22-9 83%

Reaction Conditions:

Stage #1: carbon disulfide;1,3-dibutyl-pyrimidine-2,4,6-trionewith triethylamine in dimethyl sulfoxide at 22; for 1 h;
Stage #2: 1,3-dibromo-propane in dimethyl sulfoxide at 23; for 12 h;

Steps:

1.b

To a solution of 38.3 g (0.159 mol) of intermediate 1, 3-dibutylpyrimidine- 2,4, 6 (1H, 3H, 5trione in 200 mL of DMSO at 22 °C was added 36.4 g (0.478 mol) of carbon disulfide followed by the dropwise addition of 48.4 mL (0.478 mol) of Et3N. After 1 h, 32.3 g (0.16 mol) of 1,3-dibromopropane was added and stirring was continued at 23 °C for 12 h. The darkened solution was diluted with 500 mL EtOAc and 500 mL of water. The aqueous phase was was extracted once with EtOAc and the combined organics were dried over Na, S041 filtered, and concentrated. The resulting crude oil was flushed through a short pad of silica gel eluting with EtOAc in hexanes. After concentrating, the crude oil was taken into 200 mL of boiling 20% EtOAc in hexanes solution. Upon standing at 0 °C for 1 h, the precipitated solids were isolated by filtration and dried to yield 47.4 grams of yellowed solid (83 % yield) intermediate 1, 3-dibutyl-5- (1, 3-dithian-2-ylidene) pyrimidine-2,4, 6 (lH, 3H, 5H)-trione.

References:

WO2005/77918,2005,A1 Location in patent:Page/Page column 13