Yield:-

Steps:

Multi-step reaction with 2 steps
1: tetrahydrofuran / 4 h / 0 - 20 °C
2: toluene-4-sulfonic acid; pyridine hydrochloride / water; acetonitrile / 3 h / 160 °C / Microwave irradiation

References:

Gomtsyan, Arthur;Schmidt, Robert G.;Bayburt, Erol K.;Gfesser, Gregory A.;Voight, Eric A.;Daanen, Jerome F.;Schmidt, Diana L.;Cowart, Marlon D.;Liu, Huaqing;Altenbach, Robert J.;Kort, Michael E.;Clapham, Bruce;Cox, Phil B.;Shrestha, Anurupa;Henry, Rodger;Whittern, David N.;Reilly, Regina M.;Puttfarcken, Pamela S.;Brederson, Jill-Desiree;Song, Ping;Li, Bin;Huang, Susan M.;McDonald, Heath A.;Neelands, Torben R.;McGaraughty, Steve P.;Gauvin, Donna M.;Joshi, Shailen K.;Banfor, Patricia N.;Segreti, Jason A.;Shebley, Mohamad;Faltynek, Connie R.;Dart, Michael J.;Kym, Philip R. [Journal of Medicinal Chemistry,2016,vol. 59,# 10,p. 4926 - 4947]