Synthesis of 1,1-diamines (aminals)
VAPOL metal phosphates are superior catalysts for imine amidation reactions to produce chiral N,N'-aminal products in high yields and with excellent ee values. Upon optimization, a wide substrate scope, low catalyst loading, and mild conditions are achieved.
R. Cao, J. C. Antilla, Org. Lett., 2020, 22, 5958-5962.
C-Acylimines undergo intermolecular amidation with amides to produce monoacyl gem-diamino acid derivatives in the presence of Cu(OTf)2 and PPh3 under mild conditions. This method provides an efficient access to gem-diamino acid equivalents with good to excellent yields.
S. Zhu, J. Dong, S. Fu, H. Jiang, W. Zeng, Org. Lett., 2011, 13, 4914-4917.
Chelated amino acid ester enolates react with aromatic nitro compounds in a 1,3-addition mode at the nitro group giving amino acids bearing an aryl(hydroxy)amino side chain. Two equivalents of enolate are necessary for complete conversion, because one equivalent is oxidized during the reaction.
D. Stolz, U. Kazmaier, R. Pick, Synthesis, 2006, 3341-3347.