Practical direct synthesis of -aryl-substituted azacycles from -alkyl protected arylamines using TiCl and DBU

• Published in: Organic & biomolecular chemistry 2020-07, Vol.18 (26), p.58-516
• Main Authors: Tran, Van Hieu, La, Minh Thanh, Kang, Soosung, Kim, Hee-Kwon
• Format: Article
• Language: English
• ISSN: 1477-0520; 1477-0539
• DOI: 10.1039/d0ob00880j

A novel transformation of N -alkyl protected arylamines and cyclic ethers into N -aryl substituted azacycles is described. Alkyl groups have been used for the protection of amines in organic syntheses. In this synthesis, N -alkyl protected arylamines were reacted with cyclic ethers in the presence of TiCl 4 and DBU, crucial reagents affording five- and six-membered azacycles. In particular, utilization of the novel TiCl 4 /DBU-mediated reaction allows various N -alkyl protected arylamines such as N -methyl-, N -ethyl-, N -isopropyl, and N-tert -butyl arylamines to be readily converted into N -aryl substituted azacycles in high yields. This practical approach using various N -alkyl arylamines leads to the efficient preparation of azacycles. Highly efficient direct transformations from N -alkyl protected arylamines such as N -methyl-, N -ethyl-, N -isopropyl, and N-tert -butyl arylamines into N -aryl substituted azacycles in the presence of TiCl 4 and DBU have been developed.