1: 84 percent / NaN3, NaI / dimethylsulfoxide / 18 h / 50 - 55 °C 2: 95 percent / Ph3P / diethyl ether / 24 h / Ambient temperature View Scheme

potassium tert-butylate in tetrahydrofuran T=66°C; 1.3 h; Heatingother bases (MgO, NaOEt), solvents (DMSO, EtOH); ring closure of 7-halo-3-oxo esters, C/O alkylation ratio; Product distribution;

sodium azide; sodium iodide in dimethyl sulfoxide T=50 - 55°C; 18 h;

Stage #1: <a href="#" onclick="return RXDsubstances(event, this, '385838', constants.ctx, '0')">ethyl acetoacetate</a> <b>With</b>&nbsp; <a href="#" onclick="return RXDsubstances(event, this, '906717', constants.ctx, '0')">lithium diisopropyl amide</a>&nbsp;<b>in</b>&nbsp; <a href="#" onclick="return RXDsubstances(event, this, '102391', constants.ctx, '0')">tetrahydrofuran</a> <br />T=-78&deg;C;&nbsp;&nbsp;Inert atmosphere;&nbsp;<br />Stage #2: <a href="#" onclick="return RXDsubstances(event, this, '605278', constants.ctx, '0')">1.3-chlorobromopropane</a> &nbsp;<b>in</b>&nbsp; <a href="#" onclick="return RXDsubstances(event, this, '102391', constants.ctx, '0')">tetrahydrofuran</a> <br />T=0&deg;C;&nbsp;1&nbsp;h;&nbsp;&nbsp;Inert atmosphere;&nbsp;<br /> <br /> &nbsp;