in diethyl ether Ambient temperature;

1: n-BuLi 2: 57 percent / diethyl ether / Ambient temperature View Scheme

n-butyllithium 1.) hexane, ether, 2 h, 2.) ether, overnight; Yield given. Multistep reaction;

dipyridinium dichromate in N,N-dimethyl-formamide Ambient temperature;

1: 71 percent / pyridinium dichromate / dimethylformamide / Ambient temperature 2: 1.) polyphosphoric acid (PPA), 2.) 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) / 1.) 110 deg C, 2 h, 2.) benzene, reflux, 30 min View Scheme