Chemodivergent and Enantioselective Synthesis of Spirobi[dihydrophenalene] Structures.

The development and enantioselective synthesis of two types of C2-symmetric spirobi[dihydrophenalene] structures is reported. The reaction proceeds via rhodium-catalyzed 2-fold asymmetric conjugate arylation of dienones followed by BF3·OEt2-promoted spirocyclization to give the enantiopure spiro products. Additive-dependent chemodivergent synthesis of 3,3'-diarylated 2,2',3,3'-tetrahydro-1,1'-spirobi[phenalene]-9,9'-diols (3,3'-Ar2-SPHENOLs) and the corresponding spiro diary ethers from the same intermediate is achieved. The structural properties of 3,3'-Ph2-SPHENOL are analyzed, and its application in asymmetric catalysis has been preliminarily demonstrated.