Catalytic Arylative Endo Cyclization of Gold Acetylides: Access to 3,4-Diphenyl Isoquinoline, 2,3-Diphenyl Indole, and Mesoionic Normal NHC-Gold Complex

3,4-Diphenyl isoquinoline and 2,3-diphenyl indole are readily accessed by catalytic selective bis-arylative endo cyclization of gold acetylides. The synthetic approach could be also extended to prepare six-membered mesoionic NHC complex, which could further undergo deprotonation/complexation to afford 1,3-N-heterocyclic dicarbene (NHDCs) Au-2 and Au/Ag complexes. The key vicinal diaurated alkene intermediates have been isolated and the studies on their reactivities towards coupling partners reinforce the proposed mechanisms.

Automated summary

3,4-Diphenyl isoquinoline and 2,3-diphenyl indole were synthesized by catalytic selective bis-arylative endo cyclization of gold acetylides. The approach was also extended to prepare six-membered mesoionic NHC complexes, leading to 1,3-N-heterocyclic dicarbene (NHDCs) Au-2 and Au/Ag complexes. Key intermediates were isolated and studied for their reactivity towards coupling partners, supporting proposed mechanisms.