toluene-4-sulfonic acid in chloroform T=60°C; Cyclization; 3.3 h;

1: 93 percent / TiCl4 / CHCl3 / 3.3 h / 20 °C 2: 98 percent / TBAF; H2O2; KHCO3 / tetrahydrofuran; H2O; methanol / 6 h / 40 °C View Scheme

<b>With</b>&nbsp; <a href="#" onclick="return RXDsubstances(event, this, '605283', constants.ctx, '0')">triethylamine</a>&nbsp;<b>in</b>&nbsp; <a href="#" onclick="return RXDsubstances(event, this, '1730800', constants.ctx, '0')">dichloromethane</a> <br />Acylation;&nbsp;1&nbsp;h;&nbsp;<br /> &nbsp;

<b>Multi-step reaction with 6 steps<br /> </b>1.1: n-BuLi / tetrahydrofuran; hexane / 0.83 h / -78 &deg;C<br />1.2: 97 percent / tetrahydrofuran; hexane / 2.5 h / -78 - 20 &deg;C<br />2.1: 65 percent / DIBALH / diethyl ether; hexane / 40 h / 20 &deg;C<br />3.1: 92 percent / (COCl)2; DMSO; Et₃N / CH₂Cl₂ / -78 - 20 &deg;C<br />4.1: 99 percent / NH₂OH*HCl; Na₂CO₃ / H₂O / 1 h / 20 &deg;C<br />5.1: 84 percent / LAH / diethyl ether; diisopropyl ether / 24 h / 55 &deg;C<br />6.1: 96 percent / Et₃N / CH₂Cl₂ / 1 h<br /> <br /> &nbsp;