Issue in Honor of Prof Richard R. Schmidt ARKIVOC 2013 (ii) 228-248
Benzotriazol-1-ylmethanol: An excellent bidentate ligand for the copper/palladium-catalyzed C-N and C-C coupling reaction
Rajeev R. Jha,a Jaspal Singh,a Rakesh K. Tiwari,a,b and Akhilesh K. Vermaa*
a Synthetic Organic Chemistry Research Laboratory, Department of Chemistry, University of Delhi, Delhi-110007, India b Department of Biomedical and Pharmaceutical Sciences, College of Pharmacy, University of Rhode Island, Rhode Island, USA E-mail: firstname.lastname@example.org
Dedicated to Professor Richard R. Schmidt on the occasion of his 78th anniversary
An efficient benzotriazole based N,O bidentate ligands for the Cu-catalyzed N-arylation of πexcessive nitrogen heterocycles is described. This ligand accomplishes C-N coupling of N- heterocycles and C-C coupling of boronic acids with a variety of hindered, functionalized aryl/heteroaryl halides under mild reaction conditions in good to excellent yields. Using his ligand C-N and C-C (Suzuki) couplings with bromoarenes could be conducted with less catalyst loading. A wide array of deactivated and hindered aryl halides react cleanly to afford the functionalized biaryl derivatives in high yields.
Keywords: N-Heterocycles, Cu-catalysis, N-arylation, benzotriazol-1-ylmethanol
The classical copper-mediated Ullmann reaction has strengthened the research community with the functionalities such as diaryl ethers, diaryl amines and diaryl thio-ethers, owing to their importance as structural motif in a wide range of molecules. However, the harsh reaction conditions and moderate yields give rise to increased demand for new methods to facilitate the synthesis of such compounds.1,2 Among such compounds, N-aryl heterocycles are an important class of compounds because of their significant pharmacological, biological and chemical activities.3 Accordingly, during the last decade, significant advances have been reported in the development of cross-coupling methodology.2 Traditionally, these moieties have been prepared with nucleophilic aromatic substitution or by Ullman type coupling.1,4 However, for N-aryl heterocycles, other methodologies need additional steps to convert aryl halides into the
Page 228 ©ARKAT-USA, Inc.