zinc in acetic acid Ambient temperature;

<b>Multi-step reaction with 3 steps<br /> </b>1: NBS, TFA / dimethylformamide / 7 h / Ambient temperature<br />2: imidazole / dimethylformamide / 12 h / Ambient temperature<br />3: 49 percent / 4A molecular sieves, BF₃*OEt₂ / CH₂Cl₂ / 1.5 h / 0 - 20 &deg;C<br /> <br /> &nbsp;

<b>Multi-step reaction with 2 steps<br /> </b>1: imidazole / dimethylformamide / 12 h / Ambient temperature<br />2: 49 percent / 4A molecular sieves, BF₃*OEt₂ / CH₂Cl₂ / 1.5 h / 0 - 20 &deg;C<br /> <br /> &nbsp;

<b>Multi-step reaction with 3 steps<br /> </b>1: NBS, TFA / dimethylformamide / 7 h / Ambient temperature<br />2: imidazole / dimethylformamide / 12 h / Ambient temperature<br />3: 49 percent / 4A molecular sieves, BF₃*OEt₂ / CH₂Cl₂ / 1.5 h / 0 - 20 &deg;C<br /> <br /> &nbsp;