Organic Synthesis of Ancient Windmill‐Like Window Nanogrid at Molecular Scale

A series of the windmill‐like fluorenoid nanogrid were synthesized by BF 3 · Et 2 O‐mediated Friedel–Crafts reaction. Two typical routes to synthesize square windmill‐like nanogrid ( WG4 ) were developed. A one step synthesis using an I‐shaped building block with a yield of 18 % and by‐products of triangular nanogrid ( WG3 ) and pentagon nanogrid ( WG5 ) as well as multi‐step synthesis using an l ‐shaped building block with a higher total yield of 53 %. Meanwhile, two isomers were separated for the triangle nanogrids ( WG3 ), one of which has been confirmed by single‐crystal X‐ray diffraction.