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. Author manuscript; available in PMC: 2014 Jul 5.
Published in final edited form as: J Org Chem. 2013 Jun 18;78(13):6471–6487. doi: 10.1021/jo400469t

Table 1.

Attempted Copper-Mediated Ullmann Coupling Reaction of 36a and 37a

graphic file with name nihms-495857-t0001.jpg

Entry Reaction Conditions Results
1. Cu powder (2.5 equiv),53b DMF, 100 °C, 12 h SM only
2. CuTC (3.0 equiv), N-methyl 2-pyrrolidine, 70 °C, 72 h SM only
3. Activated Cu powder (8 equiv), DMF, reflux, 72 h SM only
4. Activated Cu powder (8 equiv), N-methyl 2-pyrrolidine, sealed tube, sand bath, 140 °C, 26 h SM only
5. Activated Cu powder (8 equiv), N-methyl 2-pyrrolidine, sealed tube, sand bath, 140 °C, 72 h decomposition
6. CuTC (8 equiv), N-methyl 2-pyrrolidine, sealed tube, sand bath, 140 °C, 26–72 h decomposition

CuTC: copper(I)-thiophene-2-carboxylate; SM: Starting materials 36a or 37a.