Phosphoric Acid → HCID 68470346, compound

Participants

Reaction Conditions

Reaction Steps

A solution (0.2 M) of 4-tert-butyl 2-ethyl 5-phenyl-6H-thieno[2,3-b]pyrrole-2,4-dicarboxylate in acetic acid was treated with acetic anhydride (2.5 eq.), cyclohexanone (10 eq.) and 85% phosphoric acid (2.3 eq.). The mixture was heated at 80° C. overnight, then it was poured into ice cold ammonium hydroxide. The product was extracted with AcOEt and the combined organic layers were washed sequentially with aqueous HCl (1 N), aqueous NaHCO3 (saturated solution) and brine then dried and concentrated. The crude was dissolved in TFA and cooled to 0° C. The resulting solution (0.1 M) was treated with triethylsilane (2 eq.) and stirred at 0° C. for 1 h then solvent was evaporated to give a residue that was purified by flash chromatography on silica gel (1:9 AcOEt/petroleum ether) to afford the title compound (58%) as a solid.

Provenance & Evidence