9-(1-Acetoxy­ethyl­idene)­fluorene (`diacetyl­fluorene'), a by-product from the acetyl­ation of 9-fluorenyl­lithium

Treatment of 9-fluorenyl­lithium with acetyl chloride produces 9-acetyl­fluorene, (I), and several by-products, among which is `di­acetyl­fluorene', now characterized definitively as 9-(1-acetoxy­ethyl­idene)­fluorene [IUPAC name: (1-fluoren-9-yl­idene­)ethyl acetate], (II), C₁₇H₁₄O₂, derived from acetyl­ation of initially formed (I). Various parameters disclose substantial structural distortion within (II) emanating from A^(1,3) strain associated with the 9-(acetoxy­ethyl­idenyl)­fluorene system.