Copper(II) triflate-catalyzed and tosyl isocyanate-mediated three-step tandem synthesis of 9-arylfluorenes

Synthesis of 9,9-Disubstituted Fluorenes from 2-Iodobiphenyls and α-Diazoesters under Palladium Catalysis

“…However, the 9-arylation of fluorenes is comparatively challenging. Although quite a few methods for the synthesis of 9-arylfluorene derivatives are available, , they usually require more elaborate synthetic steps (Scheme ). Furthermore, only one aryl group is introduced for most of the reactions, and the methylene C–H bond in the 9-arylfluorenes should still be functionalized by additional reactions .…”

Total Synthesis of (−)‐Daphenylline

“…Tr iflation of phenol 25 followed by Suzuki coupling with potassium vinyltrifluoroborate and removal of the acetal protecting group afforded the desired aldehyde 13 in 90 %yield over three steps.Atthis point, the designed cascade reaction was attempted. Since awide variety of conditions (BF 3 •Et 2 O, Et 2 AlCl, TiCl 4 ,and p-TsOH) [20] did not provide any desired Friedel-Crafts cyclization products,analternative strategy was attempted to furnish the daphenylline skeleton by reversing the order of Suzuki coupling and the Friedel-Crafts cyclization. Thus,p henol 25 was protected as am ethyl ether using MeI/NaH, and subsequent aqueous acid hydrolysis of the acetal gave aldehyde 26 (88 %), Pinnick oxidation [21] of which afforded carboxylic acid 27 (93 %).…”