Z-(1S,6S)-7-(2,4-Dimethoxy-benzyl)-9-naphthalen-2-yl-7,9-diaza-bicyclo[4.2.2]dec-3-ene-8,10-dione (0.180, 0.406 mmol) was placed in a CEM microwave 10-mL pressure-rated tube and was dissolved in trifluoroacetic acid (4.25 mL) and thioanisol (0.05 mL). The reaction mixture was capped and heated in a CEM discover system laboratory microwave at 120° C. for 0.5 hours. The reaction mixture was poured into a 100 mL round bottom flask and Celite® (approximately 5 g) and ethyl acetate (20 mL) were added. The solvents were removed. The Celite®/reaction mixture was loaded into an Isco solid phase loading cartridge. Flash chromatography was carried out using an Isco Companion automated chromatography system, silica column (12 g), initially holding at 40% ethyl acetate in heptane for 8 column volumes, increasing the ethylacetate concentration to 100% over 3 column volumes, holding at 100% ethyl acetate for 20 more column volumes to yield a residue.
