Fig. 1

Synthetic routes of the central fused ring units. a Synthetic route of the central fused ring core (Compound 2) of IDIC, b optimized synthetic route of Compound 2 and c synthetic route of the central fused ring core MO-IDT
Synthetic routes of the central fused ring units. a Synthetic route of the central fused ring core (Compound 2) of IDIC, b optimized synthetic route of Compound 2 and c synthetic route of the central fused ring core MO-IDT