Design, Synthesis, and Application of a Type of Chiral Spirocyclic Naphthylamines

A family of new spirocyclic chiral mono- and diamine structures has been designed together with their de novo asymmetric synthesis, featuring a short sequence from simple substrates. This study complements the previous limited exploration of the counterparts of well-established 1,1'-spirobiindane-7,7'-diol (SPINOL) and its modified analogs. The convenient enantioselective synthesis of 2,2',3,3'-tetrahydro-1,1'-spirobi-[phenalene]-9,9'-diamine (SPHENAM) and 9'-amino-2,2',3,3'-tetrahydro-1,1'-spirobi[phenalen]-9-ol (NOSPHEN) represents a notable advantage over the limited spirocyclic precedents of this type, which were uniformly derived from their spiro parents. Two synthetic routes, both featuring catalyst-controlled enantioselective induction, have been designed, leading to the convenient construction of a large library of both C₂-symmetric and non-C₂-symmetric derivatives of 2,2',3,3'-tetrahydro-1,1'-spirobi[phenalene]-9,9'-diol (SPHENOL), all with high efficiency and enantiomeric excess. Preliminary studies have demonstrated their superior performance as backbones of diverse effective chiral catalysts and ligands, illustrating their potential in asymmetric synthesis.