Acetic Anhydride → trans-3-acetoxy-4-(2-cyanoiminothiazolidin-3-yl)-2,2-diethyl-3,4-dihydro-2H-1-benzopyran-6-carbonitrile

Participants

Reaction Steps

A mixture of trans-4-(2-cyanoiminothiazolidin-3-yl)-2,2-diethyl-3,4-dihydro-3-hydroxy-2H-1-benzopyran-6carbonitrile -(0.28 g) and acetic anhydride (0.15 ml) in pyridine (1.4 ml) was stirred overnight at ambient temperature. The reaction mixture was diluted with ethyl acetate, and then washed with 5% aqueous hydrochloric acid, saturated sodium bicarbonate solution and brine successively. The extract was dried over anhydrous magnesium sulfate and evaporated in vacuo to give a residue of trans-3-acetoxy-4-(2-cyanoiminothiazolidin-3-yl)-2,2-diethyl-3,4-dihydro-2H-1-benzopyran-6-carbonitrile, which was dissolved in toluene (12.5 ml) and thereto was added 1,8-diazabicyclo[5.4.0]undec-7-ene (0.35 ml). The reaction mixture was heated at 100° C. with stirring for an hour and 40 minutes. The solvent was evaporated in vacuo. The residue was triturated with ethyl acetate and recrystallized from 85% aqueous acetonitrile to give 4-(2-cyanoiminothiazolidin-3-yl)-2,2-diethyl-2H-1-benzopyran-6-carbonitrile (0.18 g).

Provenance & Evidence