Design of a depside with a lipophilic adamantane moiety: Synthesis, crystal structure and molecular conformation

New adamantane depsides, ethyl 2-(1-adamantyl)-3-O-[(S)-Boc-Phe]butanoate (R,R,S)-1a and (S,S,S)-1b were prepared and characterized by spectroscopic data. The crystal structures and the stereochemistry of rac-(R,R,S)-1a and threo-2-(1-adamantyl)-3-hydroxybutanoic acid rac-(R,R)-4a were determined by X-ray structure analysis. In the racemic crystal, the molecules of 1a form centrosymmetric dimers through hydrogen bonds involving a double acceptor function of the depside carbonyl oxygen, and donors of the amino group and aromatic C-H atoms. The dimers are connected through an infinite chain of C-H⋯O interactions, where C-H is an aromatic donor and the ester carbonyl oxygen is an acceptor. In the solid state, amphiphilic molecules 1a and 4a exhibit pronounced hydrophilic and hydrophobic bilayers.