e.g. Filippa Pettersson or Cancer Res. 75(6) , 1102-12, (2015) or 10.1002/anie.201600521
Tetrahedron letters
The reaction of secondary α-amino acids with carbonyl compounds. Properties of the intermediate azomethine ylides. Oxazolidine formation versus 1.4-prototropy.
Abstract Cyclic secondary α-amino acids react regiospecifically, via antidipole formation, with aldehydes bearing electron withdrawing substituents to give oxazolidines in good yield. In certain cases structural features in the α-amino acid promote a 1, 4-prototropic process ...