3-Amino-4-valerylamino thiophene → 2-butyl-1H-thieno[3,4-d]imidazole

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Reaction Steps

1 g of the product of Step A was dissolved at ambient temperature with stirring in 3 ml of phosphorous oxychloride and then the solution was heated at reflux for one hour. The solution was evaporated to dryness and 100 ml of a saturated aqueous solution of sodium bicarbonate were added. The mixture was stirred for 20 minutes at ambient temperature followed by extraction with methylene chloride. The extracts were washed with sodium bicarbonate solution and the organic phase was dried, filtered and evaporated. The oil was dissolved in 600 ml of ethyl ether at reflux, followd by filtration and evaporation to dryness to obtain 570 mg of product which was crystallized from 2 ml of isopropyl ether to obtain 500 mg of the expected product melting at 118° C.

Provenance & Evidence