urea in methanol 16 h; Ambient temperature;

<b>Multi-step reaction with 2 steps<br /> </b>1: 73 percent / pyridine / petroleum ether / r.t., 1 h then reflux 2 h<br />2: 24.4 percent / WCl₆/(CH₃)4Sn / 16 h / 70 &deg;C<br /> <br /> &nbsp;