title: Differentially-protected steroidal triamines; scaffolds with potential for medicinal, supramolecular, and combinatorial chemistry.
abstract: Cholic acid 2a has been converted into two new orthogonally-protected triamino scaffolds, 13 and 14. The synthesis proceeds via the bis-Boc-NH-substituted azide 10, for which an improved preparation is described. After removal of the Boc groups, the two axial amines are differentiated through a novel monoprotection employing 1-(2-nitrobenzenesulfonyloxy)-benzotriazole 29. Regioselectivity of > or 50 : 1 is achieved, presumably reflecting an exceptional sensitivity to steric hindrance. Protection of the remaining amino group as Boc or Alloc gives the scaffolds in approximately 40% overall yield from cholic acid. Scaffold 13 has been sequentially deprotected and derivatised with N-carbamoyl amino acids, to give a model for tripodal peptide libraries.
authors.affiliation: School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, UK.
authors.forename: Vicente
authors.initials: V
authors.lastname: del Amo
authors.forename: Laura
authors.initials: L
authors.lastname: Siracusa
authors.forename: Theodoros
authors.initials: T
authors.lastname: Markidis
authors.forename: Beatriz
authors.initials: B
authors.lastname: Baragaña
authors.forename: Khadga M
authors.initials: KM
authors.lastname: Bhattarai
authors.forename: Marta
authors.initials: M
authors.lastname: Galobardes
authors.forename: Gregorio
authors.initials: G
authors.lastname: Naredo
authors.forename: M Nieves
authors.initials: MN
authors.lastname: Pérez-Payán
authors.forename: Anthony P
authors.initials: AP
authors.lastname: Davis
mesh_terms: D000596:Amino Acids / Q000737:chemistry; D001386:Azides / Q000737:chemistry; D002625:Chemistry, Organic / Q000379:methods*; D019826:Cholic Acid / Q000737:chemistry*; D020650:Combinatorial Chemistry Techniques; D015394:Molecular Structure; D011073:Polyamines / Q000138:chemical synthesis* / Q000737:chemistry; D013237:Stereoisomerism
chemical_list: D000596:Amino Acids; D001386:Azides; D011073:Polyamines; D019826:Cholic Acid