Rehman, A.; Li, C.; Budge, L. P.; Street, S. E.; Savage, P. B. Tetrahedron Lett. 1999, 40, 1865-1868. Preparation of amino acid-appended cholic acid derivatives as sensitizers of Gram-negative bacteria.
Attachment of amino acids to cholic acid derivatives yielded compounds that sensitize Gram-negative bacteria to hydrophobic antibiotics. Incorporation of three amino acid onto a cholic acid derivative via ester bonds was only achieved with non-α-branched amino acids. Three non-α-branched or three α-branched amino acids were coupled to the steroid backbone via amide bonds.