Practical Asymmetric Synthesis of RO5114436, a CCR5 Receptor Antagonist

A practical asymmetric synthesis of a 3,7-diazabicyclo[3.3.0]octane derivative (1), a representative of a new class of potent CCR5 receptor antagonists, is described. The benzylamine stereogenic center of 1 was introduced by a ruthenium-catalyzed asymmetric reductive amination using (R)-MeOBIPHEP as ligand. Aldehyde 4, prepared by Parikh−Doering oxidation, was used without workup in the reductive amination reaction, which not only simplified the process but also overcame the instability of 4. The 3,7-diazabicyclo[3.3.0]octane core was obtained by a [3 + 2] cycloaddition.