Synthesis of Imines
A highly regio- and enantioselective copper-catalyzed three-component coupling of isocyanides, hydrosilanes, and γ,γ-disubstituted allylic phosphates/chlorides provides chiral α-quaternary formimides in the presence of a chiral naphthol-carbene ligand and LiOtBu as base. The formimides can readily be converted to α-quaternary aldehydes.
K. Hojoh, H. Ohmiya, M. Sawamura, J. Am. Chem. Soc., 2017, 139, 2184-2187.
A palladium-catalyzed double isocyanide insertion and elimination enables an efficient one-pot synthesis of α-iminonitriles from readily available aryl halides without using hypertoxic cyanides and excess oxidants. Furthermore, the utility of this reaction was demonstrated by a rapid total synthesis of a quinoxaline.
Z.-B. Chen, Y. Zhang, Q. Yuan, F.-L. Zhang, Y.-M. Zhu, J.-K. Shen, J. Org. Chem., 2016, 81, 1610-1616.
The direct conversion of amides, including sensitive N-vinyl amides, to the corresponding trimethylsilyl alkynyl imines followed by a ruthenium-catalyzed protodesilylation and cycloisomerization gives various substituted pyridines and quinolines.
M. Movassaghi, M. D. Hill, J. Am. Chem. Soc., 2006, 128, 4592-4593.
A 1,4-dipolar intermediate generated from pyridine and dimethyl acetylenedicarboxylate reacted with aldehydes to give 2-benzoylfumarates via the elimination of pyridine, whereas with N-tosylimines as dipolarophiles the reaction afforded highly substituted 1-azadienes.
V. Nair, A. R. Sreekanth, N. Abhilash, A. T. Biju, B. R. Devi, R. S. Menon, N. P. Rath, R. Srinivas, Synthesis, 2003, 1895-1902.