Short Synthesis of Orthogonally Protected 3α,12α-Diamino-5β-cholan-24-oic Acid, a Dipodal Steroid Scaffold for Combinatorial Chemistry

A short, practical, multigram‐scale synthesis of C3α‐NHAlloc, C12α‐NHBoc‐diamino‐5β‐cholan‐24‐oic acid 2 was developed, applying a new, straightforward synthetic strategy. Key features are the conservation of the carboxyl moiety at C24 during oxime reduction, the late differentiation between the C3 and C12 amino groups and the gradual separation of diastereomers during the synthesis. This orthogonally protected diamino steroid derivative can be used as starting point for the generation of steroid based dipodal peptide and non‐peptide combinatorial libraries. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)