Yield:-

Steps:

Multi-step reaction with 2 steps
1.1: dmap; triethylamine / dichloromethane / 0 - 20 °C
2.1: n-butyllithium / tetrahydrofuran; hexane / 2 h / -78 °C / Inert atmosphere; Sealed tube
2.2: 1.17 h / -78 - 20 °C / Inert atmosphere; Sealed tube
2.3: 1 h / Inert atmosphere; Sealed tube

References:

Holder, Jeffrey C.;Goodman, Emmett D.;Kikushima, Kotaro;Gatti, Michele;Marziale, Alexander N.;Stoltz, Brian M. [Tetrahedron,2015,vol. 71,# 35,art. no. 26197,p. 5781 - 5792]