Concise Synthesis of Annulated Pyrido[3,4-b]indoles via Rh(I)-Catalyzed Cyclization
Jonathan G Varelas1, Satyam Khanal1, Michael A O'Donnell1
1Department of Chemistry and Biochemistry, Providence College , 1 Cunningham Square, Providence, Rhode Island 02918, United States.
Abstract:
The synthesis of pyridines bearing multiple ring fusions poses a considerable challenge for organic chemists. To address this problem, we describe the synthesis of a small library of pyrido[3,4-b]indoles via an efficient, five-step sequence. The key transformation is a Rh(I)-catalyzed [2 + 2 + 2] cyclization that forms three rings in one reaction flask. Our method is high yielding, accommodates a variety of functional groups, and suffers no entropic costs as ring size increases.
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