1: 86 percent / Ac2O / acetic acid / 4 h / 130 - 140 °C 2: 1. Et3Al, BuLi / 1. hexane, -78 deg C, HMPT, 15 min 2. -50 deg C, 15 min View Scheme

n-butyllithium; triethylaluminum 1. hexane, -78 deg C, HMPT, 15 min 2. -50 deg C, 15 min; Yield given. Multistep reaction;