Metal-Free Multiple Carbon-Carbon and Carbon-Hydrogen Bond Activations via Charge-Switching Mechanism in Unstrained Diindolylmethanes
Chandrasekhar Challa, Sunil Varughese, Cherumuttathu H. Suresh* and Ravi S. Lankalapalli*
A transformation of the unstrained phenol substituted 3,3′-diindolylmethanes (DIPMs) to 2,3′-diindolylketones (DIKs) by double C-C single bond cleavage with associated rearrangements, triggered by phenylio-dine(III)diacetate (PIDA), is reported. Density functional theory studies reveal a mechanism involving multiple ‘charge-switching’ steps by synergistic involvement of the two indole units with overall low activation energy. The indole ‘charge-switching’ mechanism in DIPMs was further extended towards synthesis of a natural product motif cyclohepta[b]indole from biaryl appended DIBM.
Organic Letters, 2017, 19, 4219–4222.