The reaction between phloroglucinol and vic polycarbonyl compounds: extension and mechanistic elucidation of Kim's synthesis for bipolarofacial bowl-shaped compounds

Kim's serendipitous synthesis of a novel cavitand by the one-pot reaction between phloroglucinol and ninhydrin was revisited and extended. A much deeper cavitand was obtained by replacing ninhydrin with benzo[f]ninhydrin. Performing the reaction in a stepwise manner, employing both ninhydrin and benzo[f]ninhydrin, provided ‘mixed bowls’ of lower symmetry. Other cyclic polyketones, such as 1,2-indanedione and alloxan, form with phloroglucinol only partially closed structures. Crystallographic studies of the intermediate compounds in this reaction confirm Kim's postulate that the bowl formation involves hemiketal ring-openings and rearrangements.

Kim's synthesis of bowl-shaped compounds from phloroglucinol and ninhydrin was extended to produce deeper and lower-symmetry cavitands. The reaction involves cyclic hemiketal formation followed by ring-openings and rearrangements.Figure optionsDownload as PowerPoint slide