Br[C:2]1[CH:3]=[C:4]2[C:9](=[CH:10][CH:11]=1)[C:8](=[O:12])[O:7][CH2:6][CH2:5]2.C([Sn](CCCC)(CCCC)[C:18]([O:20]CC)=[CH2:19])CCC.[Sn].[Br:32]N1C(=O)CCC1=O>Cl[Pd](Cl)([P](C1C=CC=CC=1)(C1C=CC=CC=1)C1C=CC=CC=1)[P](C1C=CC=CC=1)(C1C=CC=CC=1)C1C=CC=CC=1.O1CCOCC1>[Br:32][CH2:20][C:18]([C:2]1[CH:3]=[C:4]2[C:9](=[CH:10][CH:11]=1)[C:8](=[O:12])[O:7][CH2:6][CH2:5]2)=[O:19]6-Bromo-3,4-dihydro-1H-isochromen-1-one (6.90 g, 30.4 mmol), tributyl(1-ethoxyethenyl)stannane (10.8 mL, 31.9 mmol, 1.05 equiv), and PdCl2(PPh3)2(1.07 g, 1.52 mmol, 0.05 equiv) were weighed into a 250 mL round bottom flask. To this was added dioxane (70 mL) and the resulting mixture stirred at 80° C. for 4 h. The reaction was not complete by HPLC, therefore another 0.1 equiv of tin reagent was added. After 30 min 6-bromo-3,4-dihydro-1H-isochromen-1-one had been fully consumed as indicated by HPLC. The reaction mixture was cooled to 0° C. and 35 mL THF followed by 14 mL H2O were added. To this was introduced solid N-bromosuccinimide (5.68 g, 31.9 mmol, 1.05 equiv), added in portions over 5 min. After stirring for 30 min there was still evidence of remaining enol ether, therefore NBS was added in small portions (˜300 additional mg added) until it was consumed as evidenced by HPLC. Water was then added and the mixture extracted with EtOAc. The aqueous layer was extracted 2 additional times with EtOAc, the combined organics dried with MgSO4, filtered and concentrated in vacuo. This was transferred with EtOAc to a 100 mL round bottom flask, the resulting solution concentrated to ˜25 mL total volume, at which point hexane (50 mL) was added dropwise. When complete the heterogeneous mixture was stirred for 30 min, then cooled to 0° C. and stirred for 10 min, then filtered and washed twice with hexanes. The desired product was dried under a nitrogen bag, then purified by flash chromatography (12 to 100% EtOAc/Hex) to provide the title compound.
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