1: p-toluenesulfonic acid monohydrate / benzene / 1 h / Ambient temperature 2: 5.6 g / 80percent acetic acid / 0.25 h / Ambient temperature 3: 45 percent / mercuric bromide, mercuric cyanide, molecular sieves 4A / acetonitrile / Ambient temperature 4: 95 percent / NaOMe / methanol / 1 h View Scheme

<b>With</b>&nbsp; <a href="#" onclick="return RXDsubstances(event, this, '3587155', constants.ctx, '0')">water</a>;&nbsp;<a href="#" onclick="return RXDsubstances(event, this, '742035', constants.ctx, '0')">trifluoroacetic acid</a> <br />1&nbsp;h;&nbsp;&nbsp;Ambient temperature;&nbsp;<br /> &nbsp;