Glyoxylates as versatile building blocks for the synthesis of α-amino acid and α-alkoxy acid derivatives via cationic intermediates

Glyoxylic acid and its derivatives are versatile ester-substituted aldehyde equivalents that can be used efficiently to generate precursors for reactive cationic intermediates such as iminium ions, N-acyliminium ions, N-sulfonyliminium ions, and oxycarbenium ions. These intermediates have been extensively used for the synthesis of (cyclic) cc-amino acid and alpha-alkoxyester derivatives. The research presented in this review is largely dedicated to the evaluation of the scope and limitations of glyoxylate-derived cationic intermediates in intra- and intermolecular reactions with suitable nucleophiles. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003).