Koshima Hideko, Honke Shinji
Department of Applied Chemistry, Faculty of Engineering, Ehime University, Matsuyama 790-8577, Japan.
J Org Chem. 1999 Feb 5;64(3):790-793. doi: 10.1021/jo9815195.
Although tryptamine (1), 2-thiophenecarboxylic acid (2), and 3-indoleacetic acid (4) are achiral compounds, chiral crystalline salts 1.2 and 1.4 were prepared by recrystallization from solutions of the two components. The crystal chirality is generated by the formation of a 2-fold helix in only one direction between the two molecules through the salt interaction and hydrogen bonding in the lattice. Two enantiomorphous crystals (P and M) of 1.2 and 1.4 were obtained by spontaneous crystallization and were easily discriminated by the measurement of solid-state CD spectra. The absolute configuration of P-1.2 was determined with high certainty by the Bijvoet method based on the anomalous dispersion of the sulfur atom during X-ray analysis.
