A mixture of Example 8D (3.20 g, 5.82 mmol), 1-bromo-2-chloroethane (2.413 mL, 29.1 mmol) and 1,8-diazabicyclo[5.4.0]undec-7-ene (1.843 mL, 12.23 mmol) in N,N-dimethylformamide (30 mL) was heated at 100° C. for 2 hours. Additional 1-bromo-2-chloroethane (2.413 mL, 29.1 mmol) and 1,8-diazabicyclo[5.4.0]undec-7-ene (1.843 mL, 12.23 mmol) were added and the mixture was heated at 100° C. for another 1 hour. The mixture was cooled and partitioned between ethyl acetate and water. The organic layer was washed repeatedly with brine, dried with sodium sulfate, filtered and concentrated to give the title compound as a solid which was used without purification (3.55 g, quantitative yield).
