1. Enantiospecific synthesis with amino acids. Part 1. Tryptophan as a chiron for the synthesis of α-substituted tryptophan derivatives Gregory T. Bourne,David Crich,John W. Davies,David C. Horwell J. Chem. Soc. Perkin Trans. 1 1991 1693
3. Enantiospecific synthesis with amino acids. Part 2. α-Alkylation of tryptophan: a chemical and computational investigation of cyclic tryptophan tautomers David Crich,Chat-On Chan,John W. Davies,Swaminathan Natarajan,Jeremy G. Vinter J. Chem. Soc. Perkin Trans. 2 1992 2233