Synthesis of α-amino ketones, aldehydes and derivatives
A thiol-promoted site-specific addition of 1,3-dioxolane to imines through a radical chain process enables a metal-free and redox-neutral conversion of inexpensive materials to a broad range of protected α-amino aldehydes in very good yields using only a catalytic amount of radical precursor. Both the thiol and a small amount of oxygen from air are indispensable to the success of this reaction.
H. Zeng, S. Yang, H. Li, D. Lu, Y. Gong, J.-T. Zhu, J. Org. Chem., 2018, 83, 5256-5266.
Chelated enolates are good nucleophiles for reactions with acyl halides and imidazolides affording α-amino-β-keto esters. In most cases, the reactions are over after a few minutes and preparatively useful yields are obtained, independent of the protecting groups and electrophile used. With chloroformates as acylating agents, various protected amino malonates become accessible.
K. Schultz, L. Stief, U. Kazmaier, Synthesis, 2012, 44, 600-604.