1: With PPA; Polyphosphoric acid (PPA) 2: With 2,3-dicyano-5,6-dichloro-p-benzoquinone

1: bromine / CS2 / 48 h / 40 °C 2: 1.) n-butyllithium / 1.) hexane, ether, 2 h, 2.) ether, overnight 3: 62 percent / pyridinium dichromate / dimethylformamide / Ambient temperature 4: 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

1: 1.) n-butyllithium / 1.) hexane, ether, 2 h, 2.) ether, overnight 2: 62 percent / pyridinium dichromate / dimethylformamide / Ambient temperature 3: 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

1: 62 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

PPA; 2,3-dicyano-5,6-dichloro-p-benzoquinone 1.) 110 deg C, 2 h, 2.) benzene, reflux, 30 min; Yield given. Multistep reaction;

Multistep reaction;