thiosulfate solution and extracted with ethyl acetate the organic phase was dried over anhydrous magnesium sulfate filtered and evaporated in vacuo to a residue which was subjected to flash column chromatography over silica gel 230 400 mesh using 5 10 ethyl acetate in hexane as the eluent to afford the title compound 0 88 g 81 as a pale yellow oil 0101 1 h nmr 300 mhz cdcl 3 u03b4 8 26 d 1h j 2 0 hz 7 96 d 1h j 2 0 hz 4 34 q 2h j 7 1 hz 1 87 s 2h 1 40 s 6h 1 37 s 6h 1 41 1 35 m 3h a solution of ethyl 8 iodo 2 2 4 4 tetramethyl chroman 6 carboxylate compound 24 0 88 g 2 26 mmol in triethyl amine 10 ml was treated with copper i iodide 0 043 g 0 226 mmol and sparged with argon for 5 minutes trimethylsilyl acetylene 3 ml 21 22 mmol was then added followed by dichlorobis triphenylphosphine palladium ii 0 15 9 g 0 226 mmol the resulting reaction mixture was heated at 70 u00b0 c overnight in a sealed tube it was then cooled to ambient temperature diluted with diethyl ether and.